HK1216082B - Pharmaceuticals for oral delivery - Google Patents

Description

Orally delivered drugs

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Application No. 61/772,927, filed March 5, 2013, and U.S. Provisional Application No. 61/925,443, filed January 9, 2014. The contents of each of these applications are incorporated herein by reference in their entirety.

Background Art

The Biopharmaceutical Classification System ("BCS") guidance was published in 2000 by the U.S. Food and Drug Administration ("FDA") to standardize oral dosage form development, and currently forms the basis of the scientific system for classifying drug substances based on solubility and intestinal permeability. According to the BCS, drug substances are divided into four classes based solely on their solubility and intestinal permeability: Class I: Highly soluble, highly permeable; Class II: Low solubility, highly permeable; Class III: Highly soluble, low permeable; and Class IV: Low solubility, low permeability. Poor solubility presents a significant barrier to oral absorption and bioavailability of drug candidates by reducing their dissolution rate and membrane permeation. Permeability across biological membranes is a key factor in the absorption and distribution of drugs. Poor permeability can lead to poor absorption across the gastrointestinal mucosa or poor systemic distribution.

Poor oral bioavailability ("F") is one of the main reasons for compound failure in preclinical and clinical development. Compounds with poor oral bioavailability tend to have low plasma exposure and high interindividual variability, which limits their therapeutic effectiveness. Therefore, there is a need in the art for pharmaceutical compositions with improved oral bioavailability. The present invention addresses these needs.

Summary of the Invention

The present invention provides a pharmaceutical composition suitable for oral delivery comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent.

The present invention also provides a method of enhancing the bioavailability of a therapeutically effective amount of at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV, comprising orally administering a pharmaceutical composition comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent.

The present invention also provides a method of treating a bacterial or viral infection in a subject in need thereof, comprising orally administering a pharmaceutical composition comprising at least one compound classified as BCS class II, BCS class III, or BCS class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent. The bacterial infection can be gram-positive or gram-negative.

The present invention also provides a method of treating complicated skin and skin structure infections (cSSSI) in a subject in need thereof, comprising orally administering a pharmaceutical composition comprising at least one compound classified as BCS class II, BCS class III, or BCS class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent.

The at least one compound classified as BCS class II, BCS class III, or BCS class IV may be a small molecule organic compound. The at least one compound classified as BCS class II, BCS class III, or BCS class IV may be an antibiotic or antiviral compound. The at least one compound classified as BCS class II, BCS class III, or BCS class IV may be tigecycline, zanamivir, kanamycin, tobramycin, or fenofibrate.

The pharmaceutical composition may be a solid preparation pharmaceutical composition, and the pharmaceutical composition may be a multi-layer solid preparation pharmaceutical composition.

The pH lowering compound may have a pKa of no greater than 4.2, the pH lowering compound may have a pKa of no greater than 3.0. Preferably, the pH lowering agent is sodium citrate.

The complexing agent can be a carboxylic acid complexing agent or an amino acid complexing agent. The carboxylic acid complexing agent can be acetylsalicylic acid, acetic acid, ascorbic acid, citric acid, fumaric acid, glucuronic acid, glutaric acid, glyceric acid, glycolic acid (glycocolicacid), glyoxalic acid (glyoxicacid), isocitric acid, isovaleric acid, lactic acid, maleic acid, oxaloacetic acid, oxalosuccinic acid, propionic acid, pyruvic acid, succinic acid, tartaric acid or valeric acid. Preferably, the carboxylic acid complexing agent is citric acid.

The at least one absorption enhancer may comprise an acylcarnitine. Preferably, the acylcarnitine is lauroylcarnitine. The at least one absorption enhancer may comprise a surfactant. The surfactant may be an acid-soluble bile acid.

The pharmaceutical composition may further comprise a cationic surfactant.

The pharmaceutical composition may further comprise an acid-resistant protective carrier. Preferably, the acid-resistant protective carrier is a viscous protective syrup.

The multi-layer solid dosage pharmaceutical composition comprising a complexing agent and an acid-resistant protective carrier may also comprise a water-soluble barrier layer disposed between the complexing agent and the acid-resistant protective carrier.

The present invention provides a pharmaceutical composition suitable for oral delivery comprising: at least one antibiotic or antiviral compound classified as BCS Class II, BCS Class III, or BCS Class IV; lauroylcarnitine; citric acid; and sodium citrate, wherein the composition is buffered to pH 3.5.

While the disclosure has been described in conjunction with its detailed description, the foregoing description is intended to illustrate and not limit the scope of the disclosure, which is defined by the scope of the appended claims. Other aspects, advantages, and modifications are also within the scope of the claims.

While the present disclosure has been particularly shown and described with reference to preferred aspects thereof, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the scope of the present disclosure as encompassed by the appended claims.

The patents and scientific literature cited herein represent the knowledge available to those skilled in the art. All U.S. patents and published or unpublished U.S. patent applications cited herein are incorporated herein by reference. All published foreign patents and patent applications cited herein are incorporated herein by reference. Genbank and NCBI submissions cited herein, indicated by accession numbers, are incorporated herein by reference. All other published references, documents, manuscripts, and scientific literature cited herein are incorporated herein by reference.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single IV bolus of 0.64 mg/kg.

Figure 2 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single 12 mg/kg IV bolus.

Figure 3 is a graph showing dose-adjusted mean plasma tigecycline concentrations in Sprague-Dawley rats following a single IV bolus dose of 0.64 mg/kg or 12 mg/kg.

Figure 4 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single intraduodenal (ID) injection of 4.8 mg/kg formulated in PBS.

Figure 5 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection of 9.0 mg/kg formulated in PBS.

Figure 6 is a graph showing dose-adjusted mean plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection formulated in PBS.

Figure 7 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection of 4.8 mg/kg formulated in 100 mM citric acid (CA), pH 3.5, and 26 mM lauroyl-L-carnitine (LLC).

Figure 8 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection of 9.0 mg/kg formulated in 100 mM CA (pH 3.5) and 26 mM LLC.

[0026] Figure 9 is a graph showing dose-adjusted mean plasma tigecycline concentrations in Sprague-Dawley rats following single ID injections formulated in 100 mM CA (pH 3.5) and 26 mM LLC.

Figure 10 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection of 4.8 mg/kg formulated in 400 mM CA (pH 3.5) and 26 mM LLC (only the tigecycline parent peak was used).

Figure 11 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection of 9.0 mg/kg formulated in 400 mM CA (pH 3.5) and 26 mM LLC (only the tigecycline parent peak was used).

[0026] Figure 12 is a graph showing dose-adjusted mean plasma tigecycline concentrations in Sprague-Dawley rats following single ID injections formulated in 400 mM CA (pH 3.5) and 26 mM LLC (using only the tigecycline parent peak).

Figure 13 is a graph showing individual and mean (±SD) plasma tigecycline concentrations (including tigecycline-related peaks) in Sprague-Dawley rats following a single ID injection of 4.8 mg/kg formulated in 400 mM CA (pH 3.5) and 26 mM LLC.

[0036] Figure 14 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following a single ID injection of 9.0 mg/kg formulated in 400 mM CA (pH 3.5) and 26 mM LLC (including the tigecycline-related peak).

[0036] Figure 15 is a graph showing dose-adjusted mean plasma tigecycline concentrations (including tigecycline-related peaks) in Sprague-Dawley rats following single ID injections formulated in 400 mM CA (pH 3.5) and 26 mM LLC.

[0026] Figure 16 is a graph showing mean dose-adjusted plasma tigecycline concentrations in Sprague-Dawley rats following single ID injections of various formulations of RA851 and RA853 from the preliminary feasibility study.

[0026] Figure 17 is a graph showing mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following Study RA861 - single ID injection.

[0026] Figure 18 is a graph showing dose-adjusted mean (± SD) plasma tigecycline concentrations in Study RA869-Sprague-Dawley rats.

[0046] Figure 19 is a graph showing mean (±SD) plasma tigecycline concentrations in Sprague-Dawley rats following single ID administration of tigecycline formulated in 400 mM CA and 26 mM LLC at pH 3.5 vs. pH 6.0, Study RA867.

[0046] Figure 20 is a graph showing mean plasma tigecycline clearance defined as a percentage of initial in Sprague-Dawley rats following a single ID administration (Studies RA851 and RA853).

Figure 21 is a graph showing individual PK profiles for IV formulations.

FIG22 is a graph showing the individual PK profiles of Formulation A.

FIG23 is a graph showing individual PK profiles of formulation PBS.

FIG24 is a graph showing the individual PK profiles of Formulation B.

FIG25 is a graph showing the individual PK profiles of Formulation C.

FIG26 is a graph showing the individual PK profiles of Formulation D.

FIG27 is a graph showing the mean PK profiles of zanamivir formulations at the indicated doses.

Figure 28 is a graph showing mean concentration (± SEM) of kanamycin versus time following IV bolus injection.

Figure 29 is a graph showing mean concentration (± SEM) of tobramycin versus time following an IV bolus injection.

Figure 30 is a graph showing the individual plasma kanamycin absorption profile in dogs following a single oral dose of uncoated capsules in PROSOLV ^™ (formulation JSV-003-038).

31 is a graph showing individual plasma kanamycin absorption profiles in dogs following single oral doses in uncoated capsules formulated with CA and LLC (Formulation JSV-003-039).

Figure 32 is a graph showing individual plasma profiles in dogs following a single oral dose of capsules containing 500 mg of CA (formulation JSV-003-005).

Figure 33 is a graph showing individual plasma profiles in dogs following a single oral dose of capsules containing 250 mg of CA (formulation JSV-003-052).

Figure 34 is a graph showing individual plasma profiles in dogs following a single oral dose of capsules containing 100 mg of CA (formulation JSV-003-053).

Figure 35 is a graph showing individual plasma profiles in dogs following a single oral dose of capsules containing 50 mg of CA (formulation JSV-003-054).

36 is a graph showing individual plasma profiles in dogs following a single oral dose of capsules containing 500 mg of CA in DRCAPS ^™ (formulation JSV-003-010).

37 is a graph showing individual plasma profiles in dogs following a single oral dose of capsules containing 250 mg of CA in DRCAPS ^™ (formulation JSV-003-041).

Figure 38 is a graph showing individual plasma profiles in beagle dogs following a single oral dose in PROSOLV ^™ (formulation JSV-003-050).

39 is a graph showing individual plasma profiles in beagle dogs following separate oral doses with CA and LLC (formulation JSV-003-051).

[0066] Figure 40 is a graph showing mean absorption profiles for dogs administered kanamycin formulated with 500 mg CA and 100 mg LLC in DRCAPS ^™ and enteric-coated VCAP PLUS ^™ capsules.

41 is a graph showing mean absorption profiles for dogs administered kanamycin formulated with CA and LLC or unformulated in uncoated VCAP PLUS ^™ capsules.

42 is a graph showing mean absorption profiles for dogs administered kanamycin formulated with 100 mg LLC and various concentrations of CA.

43 is a graph showing mean absorption profiles for dogs administered capsules containing tobramycin formulated with CA and LLC or unformulated.

[0066] Figure 44 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in beagle dogs following a single 1 mg (0.08 mg/kg) IV bolus (SC427).

[0066] Figure 45 is a graph showing individual and mean (±SD) plasma tigecycline concentrations in beagle dogs following a single 5 mg (0.42 mg/kg) IV bolus (SC431).

[0066] Figure 46 is a graph showing dose-adjusted mean plasma tigecycline concentrations in beagle dogs following a single IV bolus (SC427 and SC431).

[0066] Figure 47 is a graph showing individual plasma tigecycline concentrations in beagle dogs following single 15 mg (1.25 mg/kg) PO doses in enteric-coated capsules formulated or unformulated with 500 mg CA and 100 mg LLC (SC424).

[0066] Figure 48 is a graph showing mean (±SD) plasma tigecycline concentrations in beagle dogs following 15 mg (1.25 mg/kg) PO alone in enteric-coated capsules formulated with 500 mg CA and 100 mg LLC or not (SC424).

[0066] Figure 49 is a graph showing individual plasma tigecycline concentrations in beagle dogs following single 30 mg (2.5 mg/kg) PO dose of enteric coated capsules formulated with 500 mg CA and 100 mg LLC (SC430).

[0066] Figure 50 is a graph showing mean (±SD) plasma tigecycline concentrations in beagle dogs following single 30 mg (2.5 mg/kg) PO administration of enteric-coated capsules formulated with 500 mg CA and 100 mg LLC (SC430).

[0066] Figure 51 is a graph showing individual plasma tigecycline concentrations in beagle dogs following single 45 mg (3.75 mg/kg) PO dose of enteric coated capsules formulated with 500 mg CA and 100 mg LLC (SC430).

[0066] Figure 52 is a graph showing mean (±SD) plasma tigecycline concentrations in beagle dogs following single 45 mg (3.75 mg/kg) PO administration of enteric-coated capsules formulated with 500 mg CA and 100 mg LLC (SC430).

Figure 53 is a graph showing mean plasma tigecycline concentrations in beagle dogs following single PO administration of enteric coated capsules formulated with 500 mg CA and 100 mg LLC (SC424 and SC430). (Note that the time scale has been adjusted for comparison; SC424 was sampled to 4 hours, while SC430 was sampled to 24 hours.)

Figure 54 is a graph showing mean dose-adjusted plasma tigecycline concentrations in beagle dogs following single PO administration of enteric-coated capsules formulated with 500 mg CA and 100 mg LLC (SC424 and SC430). Note that the time scale has been adjusted for comparison, with SC424 sampling to 4 hours and SC430 sampling to 24 hours.

Figure 55 is a graph showing dose linearity relative to _Cmax in beagle dogs following PO administration of enteric coated capsules formulated with 500 mg CA and 100 mg LLC alone. Note that the time scale has been adjusted for comparison, with SC424 sampling to 4 hours and SC430 sampling to 24 hours.

Figure 56 is a graph showing dose linearity in beagle dogs relative to AUC _(0-4HR) following PO administration of enteric coated capsules formulated with 500 mg CA and 100 mg LLC alone. Note that the time scale has been adjusted for comparison, with SC424 sampling to 4 hours and SC430 sampling to 24 hours.

FIG57 is a graph showing the solubility of fenofibrate with increasing LLC concentration.

DETAILED DESCRIPTION

Detailed Description of the Invention

The present invention provides a pharmaceutical composition suitable for oral delivery comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent.

The at least one compound classified as BCS class II, BCS class III, or BCS class IV may be a small molecule organic compound. The at least one compound classified as BCS class II, BCS class III, or BCS class IV may be an antibiotic or antiviral compound. The at least one compound classified as BCS class II, BCS class III, or BCS class IV may be tigecycline, zanamivir, kanamycin, tobramycin, or fenofibrate.

The pharmaceutical composition may be a solid dosage pharmaceutical composition (eg, tablet, capsule) or a multilayer solid dosage pharmaceutical composition.

The pH lowering compound may have a pKa of no greater than 4.2, the pH lowering compound may have a pKa of no greater than 3.0. Preferably, the pH lowering agent is sodium citrate.

The complexing agent can be a carboxylic acid complexing agent or an amino acid complexing agent. The carboxylic acid complexing agent can be acetylsalicylic acid, acetic acid, ascorbic acid, citric acid, fumaric acid, glucuronic acid, glutaric acid, glyceric acid, ethanol (glycocolicacid), glyoxalic acid (glyoxic acid), isocitric acid, isovaleric acid, lactic acid, maleic acid, oxaloacetic acid, oxalosuccinic acid, propionic acid, pyruvic acid, succinic acid, tartaric acid or valeric acid. Preferably, the carboxylic acid complexing agent is citric acid.

The at least one absorption enhancer may comprise an acylcarnitine. Preferably, the acylcarnitine is lauroylcarnitine. The at least one absorption enhancer may comprise a surfactant. The surfactant may be an acid-soluble bile acid.

The pharmaceutical composition may further comprise a cationic surfactant.

The pharmaceutical composition may further comprise an acid-resistant protective carrier. Preferably, the acid-resistant protective carrier is a viscous protective syrup.

The multi-layer solid dosage pharmaceutical composition comprising a complexing agent and an acid-resistant protective carrier may further comprise a water-soluble barrier layer disposed between the complexing agent and the acid-resistant protective carrier.

The present invention provides a pharmaceutical composition suitable for oral delivery comprising: at least one antibiotic or antiviral compound classified as BCS Class II, BCS Class III, or BCS Class IV; lauroylcarnitine; citric acid; and sodium citrate, wherein the composition is buffered to pH 3.5.

The present invention provides a pharmaceutical composition comprising: a therapeutically effective amount of at least one compound selected from one of a Class II drug, a Class III drug, or a Class IV drug; at least one chelating agent; and at least one absorption enhancer. The composition may further comprise at least one pH-lowering agent. The composition may further comprise an acid-resistant protective carrier effective for transporting the pharmaceutical composition through the patient's stomach. The composition may further comprise a water-soluble barrier layer separating the chelating agent from the acid-resistant protective carrier. In one aspect, the chelating agent is a carboxylic acid. In one aspect, the carboxylic acid is citric acid. In one aspect, if the composition is added to 10 milliliters of 0.01 M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no greater than 5.5. In one aspect, if the composition is added to 10 milliliters of 0.05 M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no greater than 5.5. In one aspect, if the composition is added to 10 milliliters of 0.1 M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no greater than 5.5. In one aspect, the absorption enhancer is lauroylcarnitine.

Pharmaceutical composition

The present invention provides a pharmaceutical composition suitable for oral delivery comprising at least one compound classified as BCS class II, BCS class III or BCS class IV.

The Biopharmaceutical Classification System (BCS), originally developed by G. Amidon, divides orally administered drugs into four classes based on their water solubility and their permeability through the intestinal cell layer. According to the BCS, drug substances are classified as follows: Class I - high permeability, high solubility; Class II - high permeability, low solubility; Class III - low permeability, high solubility; and Class IV - low permeability, low solubility.

As used herein, a compound is considered highly soluble when the highest dose strength is soluble in <250 mL of water over the pH range of 1 to 7.5. As used herein, a compound is considered highly permeable when the extent of absorption in humans is >90% of the administered dose, as determined based on mass-balance or comparison with an intravenous reference dose. As used herein, a compound is considered rapidly soluble when >85% of the labeled amount of drug substance dissolves in a volume of <900 mL of buffer solution within 30 minutes using USP Apparatus I or II.

As used herein, a compound or drug (these terms are interchangeable) does not contain peptide bonds in its molecular structure. It should be understood that the compounds of the present invention may comprise small molecules. As used herein, the term "small molecule" refers to a low molecular weight organic, inorganic, or organometallic compound. A small molecule may comprise a molecular weight of less than 2000 Daltons. A small molecule may comprise a molecular weight of less than 500 Daltons. A small molecule may comprise a molecular weight of about 50 to 500 Daltons.

The compounds of the present invention can be compounds that target the function or growth process of bacteria, such as antibiotics. The compound can be an antibiotic comprising a central tetracyclic carbocyclic skeleton. The antibiotic can be a tetracycline or glycylcycline antibiotic. In a preferred aspect, the antibiotic is tigecycline. The compound can be capable of binding to the ribosomal subunits of bacteria. The compounds of the present invention can be compounds that target viruses or viral particles, such as antiviral agents or compounds.

The compound can be classified as a BCS class II drug, a class III drug, or a BCS class IV drug. Non-limiting examples of BCS class II drugs are: glyburide, bicalutamide, ezetimibe, fenofibrate, glipizide, atovaquone, carbamazepine, danazol, griseofulvin, ketoconazole, toglitazone, ibuprofen, nifedipine, nitrofurantoin, phenytoin, sulfamethoxazole, trimethoprim, valproic acid, praziquantel, retinyl palmitate, and sulfasalazine. Non-limiting examples of BCS Class III drugs include: cimetidine, acyclovir, atenolol, ranitidine, abacavir, captopril, chloramphenicol, codeine, colchicine, dapsone, ergotamine, kanamycin, tobramycin, tigecycline, zanamivir, hydralazine, hydrochlorothiazide, levothyroxine, methyldopa, acetaminophen, propylthiouracil, pyrodostigmine, cloxacillin sodium, thiamine, benzidazole, didanosine, ethambutol, ethosuximide, folic acid, nicotinamide, nifurtimox, and albuterol sulfate. Non-limiting examples of BCS Class IV drugs include: hydrochlorothiazide, furosemide, cyclosporine A, itraconazole, indinavir, nelfinavir, ritonavir, saquinavir, nitrofurantoin, albendazole, acetazolamide, and azithromycin.

In some preferred aspects of the invention, the compound is tigecycline. Tigecycline is the first approved member of the new glycyltetracycline class of antibiotics. Tigecycline exhibits activity against a variety of Gram-positive and Gram-negative bacterial pathogens, many of which are resistant to existing antibiotics, including, as non-limiting examples, activity against methicillin-resistant Staphylococcus aureus (MRSA), Stenotrophomonas maltophilia, Haemophilus influenzae, and multidrug-resistant strains of Neisseria gonorrhoeae (with a reported MIC value of 2 mcg/mL) and Acinetobacter baumannii. Tigecycline is licensed for the treatment of skin and soft tissue infections and intra-abdominal infections and has previously been utilized as a lyophilized powder for intravenous infusion in hospital settings, primarily due to its inherent low permeability. Tigecycline has an aqueous solubility of approximately 300 mg/mL and its permeability defects make oral administration a challenge. Known formulations exhibit a maximum oral bioavailability % (F%) of less than 5%. Commensurate with its high aqueous solubility and poor membrane permeability, tigecycline is not extensively metabolized. The drug is primarily cleared via the biliary pathway, mostly in unchanged form. In one aspect, the pharmaceutical composition of the present invention is an improved oral formulation of tigecycline. In one aspect, the pharmaceutical composition of the present invention is an oral formulation of tigecycline, which is used for oral conversion of treatment after the patient's clinical symptoms have stabilized (indicating control of infection). In one aspect, the oral formulation of tigecycline of the present invention is used to control recurrent infections in patients with no or minimal liver damage.

In some preferred aspects of the invention, the compound is zanamivir. In one aspect, the pharmaceutical composition of the present disclosure is zanamivir formulated with a pH lowering agent (e.g., buffered citric acid) and/or a penetration enhancer (e.g., lauroyl-L-carnitine) or as an emulsion (e.g., an emulsion in Capmul).

The pharmaceutical composition suitable for oral delivery comprising at least one compound classified as BCS Class II, BCS Class III or BCS Class IV of the present invention may further comprise at least one complexing agent. The complexing agent may be a carboxylic acid complexing agent or an amino acid complexing agent.

Suitable carboxylic acids that can be used as complexing agents of the present disclosure include, but are not limited to, acetylsalicylic acid, acetic acid, ascorbic acid, citric acid, fumaric acid, glucuronic acid, glutaric acid, glyceric acid, glycolic acid, glyoxylic acid, isocitric acid, isovaleric acid, lactic acid, maleic acid, oxaloacetic acid, oxalosuccinic acid, propionic acid, pyruvic acid, succinic acid, tartaric acid, valeric acid, and the like.

Suitable organic amino acids that can be used as complexing agents in the present disclosure include, but are not limited to, glutamic acid, aspartic acid, histidine, and the like.

The complexing agent can be a high affinity complexing agent. High affinity complexing agents are able to complex metal cations, thereby inhibiting salt-induced precipitation. In a preferred aspect, the complexing agent is citric acid. Citric acid has three (3) ionizable groups, distinguished by three different pKas, approximately pH = 3.09, 4.75, and 6.39. This property allows citric acid to act as a polydentate binder, or a masking agent for cationic species in solution. The net result is that citric acid is an excellent complexing agent, particularly for small metal ions such as calcium. However, within the active pH range of the current formulation (< pH 5.5), due to the pKa of each ionizable group, one would expect that a large proportion of one or two of these ionizable groups (depending on the pH) would be protonated and therefore unavailable for binding cationic salts such as calcium. Therefore, at this pH (< pH 5.5), citric acid would not be expected to be as effective as a complexing agent in this pH range as it is in more alkaline conditions.

Suitable complexing agents may also include EDTA, EGTA, phosphonates, and bisphosphonates.

Pharmaceutical compositions suitable for oral delivery comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV of the present invention may further comprise coated acid particles.

In one aspect, carboxylic acid can be provided at least in part with the acid particles of protective coating coating, to reduce the unwanted acidic interactions with other components of the preparation (such as compound and, when used, outer enteric coating). When using coated acid particles, the particles are coated with a pharmaceutically acceptable protective coating, which is non-acidic and preferably has a water solubility of at least one gram, preferably at least 10 grams, in every 100 ml of water at room temperature. Because coating is in order to reduce the acidic interactions with other components of the pharmaceutical composition, it is important that coating itself is not acidic, otherwise its own acidity can cause some acidic interactions, which is what coating hopes to stop. Good water solubility is also important for rapid dissolution, which in turn desirably contributes to the more simultaneous release of pharmaceutical acids, medicines, and absorption enhancers.

Suitable coating materials include, but are not limited to, sugars (e.g., glucose), oligosaccharides (e.g., maltodextrin), and acidic salts (e.g., sodium citrate). When an acidic salt is used, it is preferred, but not required, that the acidic salt be a salt of the coated acid (e.g., sodium citrate-coated citric acid particles). Preferred coated acid particles include, but are not limited to, maltodextrin-coated citric acid particles, which are available from Jungbunzlauer under the trademark CITROCOAT. When used as an acid, citric acid or other organic acids can be coated by spraying a coating solution containing, for example, glucose, maltodextrin, or sodium citrate onto particles of the organic acid in a fluidized bed dryer. The coatings discussed herein can be used on particles of other acids discussed herein.

The average size of the acid-coated particles can be from about 30 mesh to about 140 mesh.

The pharmaceutical compositions suitable for oral delivery of the present invention comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV may further comprise at least one pH-lowering compound.

The amount of the pH-lowering compound can be determined based on the type of pH-lowering compound used and the equivalents of protons donated by the given pH-lowering compound.

The pH-lowering compound can be any pharmaceutically acceptable compound that is non-toxic in the gastrointestinal tract and is capable of delivering hydrogen ions (Brønsted-Lowry acids) or capable of inducing higher hydrogen ion levels from the local environment (acting as an Arrhenius or Lewis acid). It can also be a combination of such compounds and/or a combination of such compounds with their respective conjugate bases to maintain the target pH. In one aspect, the at least one pH-lowering compound used in the composition has a pKa of no greater than 4.2, preferably no greater than 3.0. In one aspect, the at least one pH-lowering compound has a water solubility of at least 30 grams per 100 ml of water at room temperature.

Non-limiting examples of compounds that are Arrhenius acids or Lewis acids include metal halide salts, such as aluminum chloride and zinc chloride. Pharmaceutically acceptable traditional acids include, but are not limited to, acid salts of amino acids (such as amino acid hydrochlorides) or derivatives thereof. Their examples are acid salts of acetylglutamic acid, alanine, arginine, asparagine, aspartic acid, betaine, carnitine, carnosine, citrulline, creatine, glutamic acid, glycine, histidine, hydroxylysine, hydroxyproline, hypotaurine, isoleucine, leucine, lysine, methylhistidine, norleucine, ornithine, phenylalanine, proline, sarcosine, serine, taurine, threonine, tryptophan, tyrosine and valine.

Other useful pH-lowering compounds that are not generally referred to in the art as "acids" but that may nonetheless be helpful in the present invention are organic phosphates having at least one free phosphate hydroxyl group, such as phosphate esters (e.g., fructose 1,6-diphosphate, glucose 1,6-diphosphate, phosphoglyceric acid, and diphosphoglyceric acid). CARBOPOL ^™ (trade name BF Goodrich) and polymers such as polycarbophil can also be used to lower pH.

Pharmaceutical compositions suitable for oral delivery comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV of the present invention may further comprise at least one absorbent.

Relative to the gross weight (excluding enteric coating) of pharmaceutical composition, the presence amount of described absorption enhancer can be 0.1-20.0 weight %.Suitable absorption enhancer can be the surfactant used as dissolution enhancer and uptake enhancer.In general, " dissolution enhancer " improves the ability of component of the present disclosure to dissolve in the aqueous environment that they initially release, or dissolves in the lipophilic environment of the mucous layer arranged in the intestinal wall, or the two thereof. " transport (uptake) enhancer " (it is usually identical with the surfactant used as dissolution enhancer) is those materials that promote drug to pass through intestinal wall more easily.

One or more absorption enhancers may perform only one function (e.g., solubility), or one or more absorption enhancers may perform only the other function (e.g., uptake). It may also be a mixture of compounds, some of which provide improved solubility, some of which provide improved uptake, and/or some of which perform both. Without being limited by theory, it is believed that uptake enhancers may act by: (1) increasing disorder in the hydrophobic regions of the outer membrane of the enterocytes, thereby allowing increased transcellular transport; or (2) leaching membrane proteins, resulting in increased transcellular transport; or (3) enlarging the radius of pores between cells to increase paracellular transport.

Surfactants can be used as dissolution enhancers and uptake enhancers. For example, detergents are useful in (1) rapidly dissolving all active ingredients in the aqueous environment in which they are initially released; (2) increasing the lipophilicity of the disclosed ingredients, particularly drugs, to aid their entry into and passage through intestinal mucus; (3) enhancing the ability of drugs to cross the epithelial barrier of the brush border membrane; and (4) enhancing transcellular or paracellular transport as described herein.

When surfactant is used as absorption enhancer, they can be free-flowing powder to promote the mixing in preparation process and the filling of capsule.When attempting to increase the bioavailability of compound, the surfactant used as absorption enhancer can be selected from (i) anionic surfactant for cholesterol derivative (for example, bile acid), (ii) cationic surfactant (for example, acylcarnitine, phospholipid etc.), (iii) nonionic surfactant, and (iv) mixture of anionic surfactant (especially those with linear hydrocarbon region) and negative charge neutralizer.Negative charge neutralizer includes but is not limited to acylcarnitine, cetylpyridinium chloride etc.Described absorption enhancer can be soluble under acidic pH, especially soluble in the range of 3.0 to 5.0.

In one aspect, a combination of a cationic surfactant and an anionic surfactant may be present in the pharmaceutical composition of the present invention. In one aspect, both the cationic surfactant and the anionic surfactant may be cholesterol derivatives and both may be soluble at acidic pH.

In one aspect, a combination of acid-soluble bile acids and cationic surfactants can be present in the pharmaceutical compositions of the present invention. In one aspect, the combination can be an acylcarnitine and a sucrose ester. When a specific absorption enhancer is used alone, a cationic surfactant is preferred. Acylcarnitines (e.g., lauroylcarnitine), phospholipids, and bile acids are particularly good absorption enhancers, especially acylcarnitines. Anionic surfactants that are cholesterol derivatives are also used in some aspects. These are preferred for the purpose of avoiding interactions with the drug that interfere with drug absorption into the bloodstream.

To reduce the possibility of side effects, when used as absorption enhancers of the present disclosure, preferred detergents can be biodegradable or resorbable (e.g., biologically recyclable compounds such as bile acids, phospholipids, and/or acylcarnitines), preferably biodegradable. Acylcarnitines are believed to be particularly useful for enhancing paracellular transport.

Non-limiting examples of absorption enhancers include: (a) salicylates, such as sodium salicylate, 3-methoxysalicylate, 5-methoxysalicylate, and homovanillate; (b) bile acids, such as taurocholic acid, taurodeoxycholic acid, deoxycholic acid, cholic acid, glycholic acid, lithocholate, chenodeoxycholic acid, ursodeoxycholic acid, ursocholic acid, dehydrocholic acid, fusidic acid, and the like; (c) nonionic surfactants, such as polyoxyethylene ethers (e.g., Brij 36T, Brij 52, Brij 56, Brij 76, Brij 96, Texaphor A6, Texaphor A14, Texaphor A60, etc.), p-tert-octylphenol polyoxyethylene (Triton X-45, Triton X-100, Triton X-114, Triton X-305, etc.), nonylphenoxypolyoxyethylenes (e.g., Igepal CO series), polyoxyethylene sorbitan esters (e.g., Tween-20, Tween-80, etc.), d-alpha tocopheryl polyethylene glycol 1000 succinate (vitamin ETPGS); (d) anionic surfactants, such as dioctyl sodium sulfosuccinate (dioctyl (e) lysophospholipids, such as lysophosphatidylcholine and lysophosphatidylethanolamine; (f) acylcarnitines, acylcholines and acylamino acids, such as lauroylcarnitine, myristoylcarnitine, palmitoylcarnitine, lauroylcholine, myristoylcholine, palmitoylcholine, hexadecyllysine, N-acylphenylalanine, N-acylglycine, etc.; (g) water-soluble phospholipids, such as diheptanoylphosphatidylcholine, diheptanoylphosphatidylcholine, etc. (h) medium chain glycerides, which are mixtures of monoglycerides, diglycerides and triglycerides containing medium chain fatty acids (caprylic acid, capric acid, lauric acid, etc.); (i) ethylenediaminetetraacetic acid; (j) cationic surfactants, such as cetylpyridinium chloride, benzalkonium chloride, benzethonium chloride, etc.; (k) fatty acid derivatives of polyethylene glycol, such as Labrasol, Labrafac, etc.; and (l) alkyl sugars, such as lauryl maltoside, lauroyl sucrose, myristoyl sucrose, palmitoyl sucrose, etc. In one aspect, the absorption enhancer is lauroylcarnitine.

Pharmaceutical compositions suitable for oral delivery comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV of the present invention may further comprise an acid-resistant protective carrier.

Many acid-resistant protective carriers (enteric coatings) are well known in the art and are useful in accordance with the present disclosure. Examples include cellulose acetate phthalate, hydroxypropylmethylethylcellulose succinate, hydroxypropylmethylcellulose phthalate, carboxymethylethylcellulose, and methacrylic acid-methyl methacrylate copolymers. In one aspect, the compound, absorption enhancer (e.g., solubility and/or uptake enhancer), and carboxylic acid are contained in a protective syrup that is sufficiently viscous to allow the components of the present disclosure to pass protectively through the stomach.

For example, a suitable enteric coating can be applied to the capsule after the remaining components of the present disclosure have been loaded into the capsule. In other aspects, the enteric coating is applied to the outside of the tablet, or to the outer surface of particles of the active ingredient and then compressed into tablet form or loaded into a capsule which is itself preferably coated with an enteric coating.

All components of the present disclosure should be released from the carrier or vehicle as simultaneously as possible and dissolved in the intestinal environment. Preferably, the carrier releases the active ingredient in the small intestine, where the uptake promoter that increases transcellular or paracellular transport is less likely to cause adverse side effects than if the same uptake promoter were subsequently released in the colon. However, it should be emphasized that the present disclosure is considered to be as effective in the colon as in the small intestine. In addition to those discussed above, a large number of carriers are well known in the art. It is necessary to keep the amount of enteric coating low (especially when optimizing how the components of the present disclosure are released simultaneously). Preferably, an enteric coating of no more than 30% of the weight of the rest of the pharmaceutical composition is added (the "rest of the matter" being the pharmaceutical composition excluded from the enteric coating itself). More preferably, less than 20% of the weight of the uncoated composition is added, particularly 12% to 20% of the weight of the uncoated composition. The enteric coating should preferably be sufficient to protect the pharmaceutical composition of the present disclosure from rupture in 0.1N HCl for at least 2 hours, and then enable complete release of all ingredients of the pharmaceutical composition within thirty minutes in a dissolution tank (where the composition is rotated at 100 rpm) after the pH is raised to 6.3. In aspects of the present disclosure using a water-soluble barrier layer, less enteric coating is required, sometimes less than the amount of the water-soluble barrier layer.

The pharmaceutical composition of the present invention comprising at least one compound classified as BCS class II, BCS class III or BCS class IV suitable for oral delivery can be a solid dosage form. The pharmaceutical composition can also be a multilayer solid dosage form.

In one aspect, when the pharmaceutical composition can also be a multilayer solid dosage form, and the pharmaceutical composition comprises citric acid and an acid-resistant protective carrier, a water-soluble barrier can be present to separate the complexing agent and the acid-resistant protective carrier. In some of the following examples, conventional pharmaceutical capsules are used for the purpose of providing this barrier. Many water-soluble barriers are well known in the art, including but not limited to hydroxypropyl methylcellulose and conventional pharmaceutical gelatin.

In one aspect, peptides (e.g., albumin, casein, soy protein, other animal or plant proteins, etc.) can be included to reduce nonspecific adsorption (e.g., binding of the peptide to the intestinal mucus barrier). When added, the peptide is preferably present in an amount of 1.0 to 10.0% by weight relative to the weight of the total pharmaceutical composition (excluding protective carriers). Preferably, the peptide is not physiologically active, and most preferably is a food peptide, such as a soy peptide.

All pharmaceutical compositions of the present disclosure may also contain common pharmaceutical diluents, glidants, fillers, lubricants, antioxidants, gelatin capsules, preservatives, colorants, etc. in their generally known sizes and amounts.

Suitable fillers may be utilized, including cellulosic fillers such as PROSOLV ^™ available from JRS Pharma. Other fillers known in the art may also be utilized.

Any disintegrant that functions to increase the dissolution rate may be used. Non-limiting examples of suitable disintegrants include POLYPLASDONE, EXPLOTAB, and AC-DI-SOL, available from International Specialty Products, JRS Pharma, and FMC Biopolymer, respectively. Preferably, the disintegrant is present in an amount of 1 to 15% by weight relative to the total tablet weight (when tablets are used), excluding any water-soluble barrier layer and any acid-resistant protective carrier.

Any glidant that functions to improve powder flowability may be used. Non-limiting examples of suitable glidants include talc, calcium silicate, magnesium silicate, and silicon dioxide. Preferably, the glidant is present in an amount of 0.1 to 2.0% by weight relative to the weight of the pharmaceutical composition, excluding any water-soluble barrier layer and any acid-resistant protective carrier.

Any lubricant that functions to prevent the powder from sticking to processing tools can be used. Non-limiting examples of suitable lubricants include stearic acid, magnesium stearate, and Type 1 hydrogenated vegetable oil. Preferably, the lubricant is present in an amount of 0.5 to 5.0% by weight relative to the weight of the pharmaceutical composition, excluding any water-soluble barrier layer and any acid-resistant protective carrier.

Non-limiting examples of suitable antioxidants include sodium pyruvate, derivatives of sodium pyruvate, ascorbic acid, ascorbyl palmitate, butylated hydroxyanisole, butylated hydroxytoluene, sodium bisulfate, and sodium metabisulfite. Preferably, the antioxidant is present in an amount of 0.5 to 5 mg per tablet.

The pharmaceutical composition may also contain peptides (e.g., albumin, casein, soy protein, other animal or plant proteins, etc.) to reduce nonspecific adsorption (e.g., binding of the peptide to the intestinal mucus barrier), thereby reducing the required concentration of the drug. When added, the peptide is preferably present in an amount of 1.0 to 10.0% by weight relative to the weight of the total pharmaceutical composition (excluding any water-soluble barrier layer and any acid-resistant protective carrier). Preferably, the peptide is not physiologically active, and most preferably is a food peptide, such as a soy peptide.

The pharmaceutical composition can be in a solid dosage form. One suitable solid dosage form is a tablet. When the pharmaceutical composition is a tablet, it can also contain a pharmaceutical binder for dry tableting. Non-limiting examples of suitable binders include KOLLIDON VA64, KOLLIDON VA64fine, KOLLIDON 30, AVICEL PH-101, PHARMACOAT 606, and MALDEX. The first three are commercially available from BASF, and the latter three are commercially available from FMC Biopolymer, Shin-Etsu, and Amylum, respectively.

To promote simultaneous release, thorough mixing of the components of the pharmaceutical composition (except any optional enteric coating or barrier layer) results in a substantially uniform dispersion of the components within the adhesive. For this reason, the coated acid particles (when used) are considered to be a single component. Uniform dispersion of the acid (or, when used, the coated acid particles) and the drug is particularly preferred.

When made into tablet form, preferably the maximum weight loss during the friability test is not greater than 1%.As used herein, the friability test refers to the technique described in "Tablet Friability", Chapter 1216, USP 28, page 2745.

In one aspect, the weight ratio of citric acid to absorption enhancer can be between 3: 1 and 20: 1, preferably 4: 1-12: 1, and most preferably 5: 1-10: 1. In a given pharmaceutical composition, the total weight of citric acid and the total weight of absorption enhancer are included in the aforementioned preferred ratios.

In one aspect, the compound, pH lowering compound, and absorption enhancer (whether a single compound or multiple compounds in each class) are uniformly dispersed in the pharmaceutical composition. The pharmaceutical composition can comprise particles containing a drug binder in which the drug, citric acid, and absorption enhancer are uniformly dispersed. Preferred particles can also consist of an acid core (which is surrounded by a uniform organic acid layer), an enhancer layer, and a drug layer surrounded by an organic acid outer layer. The particles can be made from an aqueous mixture consisting of a drug binder (e.g., polyvinyl pyrrolidone or hydroxypropyl methylcellulose), citric acid, an absorption enhancer, and the drug of the present disclosure, or can be made by a dry granulation process. Other aspects include matrix or other tablet or capsule-based systems that can include multiple granulation phases, such as granulation of the drug, with or without solubilizing excipients and other processing excipients, consistent with the external granulation of citric acid.

Use other processing technology as known in the art, also can realize the solubilizing of low water solubility or water-insoluble compound.This technology includes but not limited to, uses suitable, pharmaceutically acceptable polymer, as spray-drying, freeze drying or the hot melt extrusion of PVP, HPMC, HPMCP, HPMCAS, PEG, PVP/VA, MME, CAP, poloxamer, gelucire, tween, Eudragit, CMEC, gelatin etc., to form amorphous dispersion.Many other such other excipients will be apparent to those skilled in the art.Penetration enhancer can be used as surfactant, to promote the formation of dispersion in the process, keeps its penetration enhancing its effect in vivo simultaneously.Then, these aspects can be filled into capsule as dry mixture with remaining active substance and processing excipient under granulation or not granulation, or be pressed into tablet.

In one aspect, a pharmaceutical composition of the invention comprises a size 00 gelatin or HPMC capsule filled with 50 mg of the compound, 500 mg of granular citric acid (eg, available from Archer Daniels Midland Corp.), and 50 mg of lauroylcarnitine (SIGMA).

All ingredients are preferably inserted last into a gelatin or HPMC capsule, and preferably are powders that can be added to the blender in any order. Thereafter, the blender is run for approximately five minutes until the powders are thoroughly mixed. The mixed powder is then loaded into the large end of the capsule. The other end of the capsule is then added and quickly sealed. 500 or more such capsules can be added to a coating apparatus (e.g., a Vector LDCS 20/30 Laboratory Development Coating System (available from Vector Corp., Marion, Iowa)).

Prepare an enteric coating solution as follows. Weigh 500 grams of EUDRAGIT L30D-55 (poly(methacrylic acid-co-ethyl acrylate) 1:1; methacrylic acid-ethyl acrylate copolymer (1:1); enteric coating available from Evonik). Add 411 grams of distilled water, 15 grams of triethyl citrate, and 38 grams of talc. This amount will be sufficient to coat approximately 500 size 00 capsules.

The capsules are film coated using methods known in the art.

Due to the increased bioavailability provided by the present disclosure, the concentration of expensive drugs in the pharmaceutical formulations of the present disclosure can be kept relatively low.

In one aspect, the pharmaceutical composition of the present disclosure is a tablet, which is prepared as follows:

1. High shear or COMIL ^™ geometric mixing of drug and microcrystalline cellulose (PROSOLV ^™ - eg PROSOLV ^™ HD90).

2. Add the mixed ingredients from step 1 to the V blender along with Citric Acid DC F20, Lauroyl-L-Carnitine, Crospovidone, KOLLIDON VA64 and Sodium Pyruvate. Mix in the V blender.

3. Add magnesium stearate to the V blender after step 2. Blend briefly in the V blender.

4. Compress the mixture into tablets.

5. Coat the tablets with an optional water soluble barrier, such as hydroxypropylmethylcellulose (HPMC) or PVA subcoat, to a weight gain of 6%.

6. Coat the tablets with an optional enteric coating (EUDRAGIT L30D-55) to a weight gain of 7%.

Treatment

The present invention also provides a method of enhancing the bioavailability of a therapeutically effective amount of at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV, comprising orally administering a pharmaceutical composition comprising at least one compound classified as BCS Class II, BCS Class III, or BCS Class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent.

The present invention also provides a method of treating a bacterial or viral infection in a subject in need thereof, comprising orally administering a pharmaceutical composition comprising at least one compound classified as BCS class II, BCS class III, or BCS class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent. The bacterial infection can be gram-positive or gram-negative.

The present invention also provides a method of treating complicated skin and skin structure infections (cSSSI) in a subject in need thereof, comprising orally administering a pharmaceutical composition comprising at least one compound classified as BCS class II, BCS class III, or BCS class IV; at least one absorption enhancer; at least one pH-lowering compound; and at least one complexing agent.

As used herein, the terms "subject" and "patient" describe an organism, including a mammal, to whom treatment using the compositions and methods of the present invention is provided. A "subject" includes a mammal. The mammal can be, for example, any mammal, such as a human, a primate, a bird, a mouse, a rat, a poultry, a dog, a cat, a cow, a horse, a sheep, a camel, a goat, or a pig. Preferably, the mammal is a human. The terms "subject" and "patient" are used interchangeably herein.

As used herein, the term "therapeutically effective amount" refers to an amount of a pharmaceutical composition that treats, alleviates, or prevents a defined disease or condition, or an amount of a pharmaceutical composition that exhibits a detectable therapeutic or inhibitory effect. The effect can be detected by any assay known in the art. The precise effective amount for a subject will depend on the subject's weight, size, and health; the nature and extent of the condition; and the therapeutic agent or combination of therapeutic agents selected for administration.

According to aspects described herein, methods are disclosed for enhancing the bioavailability of an orally delivered Class II, III, or IV drug, comprising selectively releasing a therapeutically effective amount of the drug with at least one complexing agent and at least one absorption enhancer to the intestine of a patient after the drug, complexing agent, and absorption enhancer have passed through the patient's mouth and stomach.

According to aspects described herein, an oral pharmaceutical composition is disclosed comprising a therapeutically effective amount of tigecycline; a sufficient amount of citric acid to produce complexing properties; and lauroylcarnitine. In one aspect, the composition further comprises at least one pH-lowering agent. In one aspect, the composition further comprises an acid-resistant protective carrier that effectively transports the pharmaceutical composition through the patient's stomach. In one aspect, the composition further comprises a water-soluble barrier layer that separates the citric acid from the acid-resistant protective carrier. In one aspect, if the composition is added to ten milliliters of a 0.01M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no greater than 5.5. In one aspect, if the composition is added to ten milliliters of a 0.05M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no greater than 5.5. In one aspect, if the composition is added to ten milliliters of a 0.1M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no greater than 5.5.

According to aspects described herein, methods are disclosed for enhancing the bioavailability of orally delivered tigecycline, comprising selectively releasing a therapeutically effective amount of tigecycline with sufficient amounts of citric acid and lauroylcarnitine to the intestine of a patient after the tigecycline, citric acid, and lauroylcarnitine have passed through the patient's mouth and stomach.

According to the present disclosure, the use of an absorption enhancer and a complexing agent simultaneously provides an unexpected synergistic effect on bioavailability relative to a single absorption enhancer or a single complexing agent. Without being limited to theory, the oral pharmaceutical composition of the present disclosure is believed to overcome a series of different and unrelated natural barriers to bioavailability. The components of the pharmaceutical composition overcome different barriers through their own appropriate mechanisms and produce a synergistic effect on the bioavailability of Class II, III or IV drugs. Due to the complexed form in the internal organs, some Class II, III or IV drugs, alone or in the presence of cationic metal salts, have reduced bioavailability. Without being limited to theory, it is believed that when sufficient citric acid is used as the complexing agent of the disclosed composition, the citric acid can serve as a high-affinity complexing agent. As used herein, the term "high-affinity complexing agent" refers to a complexing agent that exhibits a low equilibrium dissociation constant ( _Kd ) for each of the metal salts described. For example, citric acid is believed to complex cationic metal salts, so cationic metal salts cannot interfere with the body's ability to absorb Class II, III or IV drugs. Without intending to be bound by theory, based on the present disclosure, it appears that the Class II, III, or IV drug administered in the pharmaceutical compositions of the present disclosure is transported through the stomach along with the complexing agent (ie, the dosage form passes through the pylorus intact).

According to aspects described herein, methods for treating patients with Gram-positive or Gram-negative bacterial pathogens are disclosed, comprising orally administering to the patient a solid dosage form, wherein the solid dosage form comprises a therapeutically effective amount of tigecycline, at least one chelating agent, and at least one absorption enhancer. In one aspect, methods for treating patients with complicated skin and skin structure infections (cSSSIs) are disclosed, comprising orally administering to the patient a solid dosage form, wherein the solid dosage form comprises a therapeutically effective amount of tigecycline, at least one chelating agent, and at least one absorption enhancer. In one aspect, methods for treating patients with complicated intra-abdominal infections (cIAIs) are disclosed, comprising orally administering to the patient a solid dosage form, wherein the solid dosage form comprises a therapeutically effective amount of tigecycline, at least one chelating agent, and at least one absorption enhancer. In one aspect, the at least one chelating agent is a sufficient amount of citric acid.

According to the present disclosure, a pharmaceutical composition thereof (at an appropriate dose) is provided to a patient in need of treatment with a Class II, III, or IV drug, preferably but not necessarily in the form of tablets or capsules of conventional sizes in the pharmaceutical industry. The dosage and frequency of administration of the product are discussed in more detail below. Patients who may benefit are any patient suffering from a condition that responds well to increased drug levels. For example, antibiotics according to the present disclosure can be used to treat patients with bacterial infections, protozoal infections, and immunomodulation. In addition, antibiotics according to the present disclosure can be used to prevent infection of surgical wounds, as dental antibiotic prophylaxis, and for the symptoms of neutropenia. For example, vitamins according to the present disclosure can be used to treat patients with vitamin deficiencies. Well-known deficiencies of human vitamins involve thiamine (beriberi), niacin (pellagra), vitamin C (scurvy), and vitamin D (rickets).

By definition, II, III or IV class drugs, taken alone or in combination, have reduced bioavailability due to precipitation in the gastrointestinal medium, their physicochemical properties hinder membrane penetration (whether due to the inherent function of the molecule of the physicochemical properties, or through transport mechanism, membrane deposition, protein-drug interaction, metabolism, etc.). As for some BCSII, III or IV class drugs, precipitation or insolubility can be the inherent properties of the molecule, or can occur by ionic interaction, such as in the presence of inorganic or organic salts, hydrophobic interactions, etc. In one aspect, carboxylic acids are used as high-affinity complexing agents of the present disclosure. Without being limited to theory, according to the present disclosure, it seems that the II, III or IV class drugs administered by pharmaceutical compositions of the present disclosure are transported through the gastrointestinal epithelium. Acids are believed to complex cationic metals, thereby inhibiting salt-induced precipitation, while also serving as promoters for paracellular absorption.

In one aspect, acid is multifunctional and is used as calcium chelating agent, pH lowering agent, bioavailability enhancer, penetration enhancer and membrane wetting/charge dispersant. For complexed calcium, acid is as penetration enhancer by opening tight junction. In addition, the chelating agent that is a pH lowering agent can further increase paracellular osmosis by inducing intracellular acidosis, resulting in actomyosin contraction of the event mediated by PKC. For shielding free metal, it can no longer suppress the solubility of the drug, or induces precipitation by the formation of complex, or the formation of salt-induced precipitation, or keeps the integrity of tight junction by cadherin interaction. For example, it has been shown that different types of antibiotics interact with calcium. In addition, citric acid can also be used as pH lowering agent, thereby increasing paracellular absorption by inducing intracellular acidosis, resulting in actomyosin contraction and increased paracellular flux.

Furthermore, without being bound by theory, carboxylic acids may modify the activity of membrane-bound transporters by modifying the ability of the membrane to disperse charge, thereby increasing absorption flux.

It is believed that the mechanism by which the present disclosure achieves the goal of improving the bioavailability of Class II, III, or IV drugs is by virtue of the simultaneous release of the active ingredients of the pharmaceutical composition as much as possible. The absorption enhancer, which can be a solubility enhancer and/or a transport enhancer (as described in more detail below), assists in the transport of the drug from the gastrointestinal tract to the blood. Many surfactants can be used as both solubility enhancers and transport (uptake) enhancers. Again, without intending to be limited by theory, it is believed that the enhanced solubility provides: (1) a more simultaneous release of the active ingredients of the disclosure to the aqueous portion of the intestine, and (2) better solubility of the drug in the mucus layer along the intestinal wall, and transport therethrough. Once the drug reaches the intestinal wall, the uptake enhancer provides better transport through the brush border membrane of the intestine into the blood via transcellular or paracellular transport. As discussed in more detail below, many preferred compounds can provide both of these functions. In those examples, preferred aspects of utilizing both of these functions can achieve this goal by adding only one additional compound to the pharmaceutical composition. In other aspects, separate absorption enhancers can provide these two functions separately.

In one aspect, a single solid dosage form is used in each administration. Nearly simultaneous release is best achieved by administering all components of the invention in a single tablet, pill, or capsule. However, the invention also encompasses, for example, splitting the required amounts of acid and enhancer into two or more capsules that can be administered together so that they together provide the necessary amounts of all ingredients.

Example 1. Administration of Tigecycline in Rats

Material

Animals and test substances

Naive female Sprague-Dawley rats (Taconic Farms, Germantown, NY) were housed in groups of three in a climate-controlled room (12:12 h light-dark cycle; food and water were available ad libitum). Animals weighed approximately 250 g at the time of testing. Rats were fasted overnight (water was available) before dosing. Information on the test article, tigecycline, is listed in the table. Tigecycline stock solutions were freshly prepared in water on the day of each study and diluted in the indicated formulations.

Table 1. Test product information

project Compound name Catalog Number Batch/lot number supplier Test product Tigecycline S-1403 S140301 Selleck Chemical Co.

method

Dosage and route of administration

The intravenous (IV) dose was administered as a bolus injection into the left carotid artery at a dose volume of 1.6 mL/kg. The intraduodenal dose was administered as a bolus injection into the duodenum at a dose volume of 1.2 mL/kg. Details of the doses and formulation compositions used for the preliminary feasibility evaluation are summarized in Table 2.

Table 2. Target dose and formulation for the initial feasibility study

^1. Dulbecco's phosphate buffered saline, Invitrogen (137 mM NaCl, 2.7 mM KCl, 10 mM Na ₂ HPO ₄ , 2 mM KH ₂ PO ₄ )

^2- Lauroyl-L-carnitine, custom synthesis, Lonza

³ -coated CA (DC F20), Jungbunzlauer

⁴ Sodium Citrate, Dihydrate, JT Baker, Reagent

Additional studies were conducted to compare the F% and PK profiles of tigecycline formulated in one of the active excipients (RA861 and RA869) compared to the highest F% formulation from the preliminary feasibility study (400 mM CA and 26 mM LLC, pH 3.5, from studies RA851 and RA853). Additional studies were conducted to explore the effect of formulation pH at constant CA and LLC concentrations (RA867).

Table 3. Target doses and formulations for secondary mechanism studies

^1. Dulbecco's phosphate buffered saline, Invitrogen (137 mM NaCl, 2.7 mM KCl, 10 mM Na ₂ HPO ₄ , 2 mM KH ₂ PO ₄ )

^2- Lauroyl-L-carnitine, custom synthesis, Lonza

³ coated CA (DC F20), Jungbunzlauer

⁴ Sodium Citrate, Dihydrate, JT Baker, Reagent

⁵ Unless otherwise stated, citrate buffer was prepared at pH 3.5

Anesthesia and catheterization

Female rats were housed in groups of three in polycarbonate (or equivalent) shoebox cages with fresh wood chip bedding at 20-22°C under a 12-hour light-dark cycle. Rats were fasted overnight prior to surgery and anesthetized by intramuscular injection of 0.3 mL of fresh ketamine (67 mg/mL)/xylazine (42 mg/mL) in 0.9% saline into the hind ribs. After the rats collapsed, they were injected intraperitoneally (IP) with 0.1 mL of ketamine/xylazine. Anesthesia was maintained by IP injection of ketamine/xylazine as needed. Animal weights were determined post-anesthesia induction.

By exposing the trachea with Mayo scissors, the indwelling catheter for blood sampling is inserted into the right carotid artery, the bottom of the artery is clamped, and the top is tied with surgical sutures. With small sharp scissors, a notch is cut in the middle area, and an Intramedic polyethylene tube is inserted into the notch area. The artery with the catheter is sealed with a line to prevent leakage. No. 23 Intramedic Luer end adapters (Luer Stub Adapter) are inserted into the cannula and connected to a 3-way valve, which is connected to a 3cc syringe filled with 0.9% normal saline and a 1cc syringe filled with 5U/mL heparin sodium for blood sampling.

IV studies

In the IV phase, tigecycline was administered to a group of three naive anesthetized female rats as a bolus injection away from the brain via the left carotid artery, which was constricted in the direction of the brain. Blood samples (~0.5 mL) for plasma tigecycline concentration analysis were collected from a cannula surgically implanted in the right carotid artery before dosing and at predetermined time points up to 120 or 240 minutes after dosing depending on the study. Blood samples were collected in tubes containing 20 μL of 180 mM EDTA. The tubes were kept on ice and then centrifuged at approximately 3000 rpm for 5 minutes at 4°C. Plasma was collected immediately after sample centrifugation and stored at -20°C for analysis.

Intraduodenal studies

Intraduodenal injection was used to simulate oral administration of enteric-coated capsules or tablet formulations. In the ID phase of the study, tigecycline was administered to naive female rats into the duodenum via a 1 mL syringe connected to a 27-gauge needle. The duodenum was exposed using Mayo surgical scissors and the administration site was determined by measuring 5 cm from the junction of the stomach and duodenum toward the jejunum. The measurement site was confirmed by inserting a small piece of surgical suture below the injection site. After the injection of the formulation, the abdominal cavity was closed with surgical forceps. Blood samples (~0.5 mL) for plasma tigecycline concentration analysis were collected from a cannula surgically implanted in the right carotid artery before administration and at a predetermined time point of up to 120 or 240 minutes after administration depending on the study.

Blood samples were collected in tubes containing 20 μL of 180 mM EDTA. The tubes were kept on ice and then centrifuged at approximately 3000 rpm for 5 minutes at 4°C. Plasma was collected immediately after centrifugation and stored at -20°C until analysis.

Analytical Procedure for Tigecycline

Quantitative determination of tigecycline in rat plasma was performed using HPLC analysis with UV detection at 350 nm. Minocycline (VWR international) was used as an internal standard. Sample processing/cleanup of plasma samples was performed offline by protein precipitation with acidified acetonitrile.

The HPLC system consisted of a Shimadzu SIL-HTc HPLC system equipped with dual Shimadzu LC-10AD vpisopump pumps, a Shimadzu CTO-10ASvp column temperature controller, and a Shimadzu SPD-10Avp variable wavelength detector. Chromatographic separation was based on Li et al., with some notable differences (see Li et al., 2004, Quantitation of tigecycline, a novel glycylcycline, by liquid chromatography. J Chromatography B. 811: 225-229). HPLC separation was performed on a reversed-phase column (Phenomenex Luna Cl8(2), 5 μm, 150×4.6 mm, part number: 00F-4252-E0) using an initial isocratic phase followed by a gradient elution of tigecycline. Mobile phase A consisted of 23 mM phosphate buffer (pH 2.5) with 6 mM 1-octanesulfonic acid, while mobile phase B consisted of pure acetonitrile. The time program started with an isocratic elution of 25% mobile phase B for 6 minutes, followed by a linear increase of mobile phase B to 35% (16 minutes) over the next 10 minutes. The system equilibrated to 25% mobile phase B for an additional 2 minutes, resulting in a total run time of 18 minutes per sample. The flow rate of the mobile phase was 1.2 mL/min. Detection was performed using an SPD-10Avp variable wavelength detector set at 350 nm with a sensitivity of 0.001 aufs.

Unknown samples and calibration standards (tigecycline in pooled rat plasma) were processed by protein precipitation with acetonitrile spiked with an internal standard. Samples were then centrifuged at 13k rpm for 30 minutes under refrigerated conditions. The supernatant was removed and the liquid was removed to dryness in a turbovap. The samples were then reconstituted in 55 μL of 0.1 M phosphate buffer (pH 3.8). The samples were maintained at 10°C while queued on the autosampler. The injection volume was 50 μL. Unknown concentrations in rat plasma samples were determined by interpolating the peak area ratios of analyte:internal standard to their nominal concentration ratios into a regression line obtained from calibration standards spiked into pooled rat plasma. Weighted regression was not used in the calculations. The method was shown to be linear to 0.05 μg/mL (defined limit of quantitation). The calibration curve covered the range of 0.05 μg/mL to 5.0 μg/mL.

Due to analytical issues observed in the analysis of early study samples, minor changes were made to the analytical method for later samples. Mobile phase A was changed to 23 mM phosphate buffer (pH 2.5) containing 4 mM 1-octanesulfonic acid, while mobile phase B was changed to 90% acetonitrile, 10% water containing 2 mM 1-octanesulfonic acid. The time program began with an isocratic elution of 25% mobile phase B for 6 minutes, followed by a linear increase to 35% mobile phase B over the next 8 minutes (14 minutes), after which the system equilibrated to 25% mobile phase B for an additional 4 minutes, resulting in a total run time of 18 minutes. The total run time, detection wavelength, flow rate, injection volume, column, and column temperature remained unchanged. Furthermore, to aid sample cleanup, the protein precipitant was acidified with 0.5% v/v TFA. The resulting precipitate was centrifuged at 13 krpm for 5 minutes, and the dried extract was reconstituted in 60 μL of mobile phase A. The reconstituted pellet was further centrifuged at 5 krpm to pellet any insoluble material, and the supernatant was injected. These changes, listed in Table 4 below, resulted in a more reliable analytical method that exhibited better resolution between tigecycline and minocycline, better signal-to-noise ratios, and eliminated precipitation issues observed in previous runs. It should be noted, however, that when the method was transferred to an older HPLC system (equipped with a Shimadzu SCT-10Avp system controller and SIL-10A autosampler), the time program was further altered to a gradient of 38% mobile phase B to accommodate the programming change. All other parameters remained unchanged.

Table 4. Comparison of RP-HPLC analysis methods for tigecycline

Pharmacokinetic data processing

Tigecycline PK parameters were calculated for each rat using non-compartmental analysis with the PK function for Microsoft Excel.

Results: Preliminary Feasibility Studies (RA851, RA853)

Plasma tigecycline after IV administration

The mean _Cmax of plasma tigecycline at the target dose of 0.64 mg/kg was 1.79 μg/mL and was observed at a mean time ( _Tmax ) of 5 minutes (0.08 hours; Table 5). As expected based on the reported single-dose half-life of approximately 20 hours, tigecycline was measurable within 4 hours. The mean AUC _(0-t) was 58.20 μg*min/mL.

When the target dose was increased to 12 mg/kg (RA853), the mean _Cmax increased to 50.7 μg/mL, which was also observed at a _Tmax of 5 minutes (Table 5). In both studies (RA851 and RA853), there was a clear biphasic profile of tigecycline, which was initially very rapid and reached steady state at approximately 30 minutes (Figures 1, 2, and 3). The mean AUC _(0-t) in study RA853 was 791 μg*min/mL.

Table 5. Plasma Concentrations and Pharmacokinetics of Tigecycline in Sprague-Dawley Rats Following a Single IV Bolus Dose of 0.64 mg/kg or 12 mg/kg

Plasma tigecycline after ID administration

Tigecycline was administered ID in PBS or in 26 mM LLC containing 100 mM CA (pH 3.5) or 400 mM CA (pH 3.5). Tigecycline administered in PBS showed little absorption at the target doses of 4.8 or 9.0 mg/kg (Table 6). In RA851 (4.8 mg/kg), the mean _Cmax was 0.10 μg/mL, which occurred at a mean _Tmax of 90 minutes, while at the higher dose, the mean _Cmax was 0.22 μg/mL, which occurred at a mean _Tmax of 30 minutes. The final results exclude one animal that showed quite significant absorption, with a _Cmax of 1.11 μg/mL at 10 minutes. The high degree of absorption, coupled with the early _Tmax , is unusual relative to the other five animals given tigecycline formulated in PBS and suggests an administration error due to inadvertent ID injection site leakage (resulting in IP administration). Compared to the IV curve at 0.64 mg/kg, the mean F% based on AUC _(0-t) was 1.6% when administered at 4.8 mg/kg and 2.8% when administered at 9.0 mg/kg.

In the presence of 26 mM LLC and 100 mM citrate (pH 3.5), tigecycline plasma concentrations increased significantly (7-9×), and the PK data are summarized in Table 7. When dosed at 4.8 mg/kg (RA851), the mean tigecycline _Cmax was 0.71 μg/mL, occurring at a mean _Tmax of 20 minutes. The mean AUC _(0-t) was 49.4 μg*min/mL, resulting in a calculated mean F% of 10.9% (CV 52.1% compared to 0.64 mg/kg IV). Increasing the dose to 9.0 mg/kg in the presence of 100 mM CA and 26 mM LLC also showed a significant increase in tigecycline plasma concentrations, with a mean _Cmax of 2.06 μg/mL at a mean _Tmax of 17 minutes. The mean AUC _(0-t) was 76.9 μg*min/mL, resulting in a mean F% of 11.4% (CV, 59.3%). Briefly, when formulated in 100 mM CA (pH 3.5), 26 mM LLC, the average F% increased 4-7 fold.

Increasing the citrate concentration to 400 mM in the presence of 26 mM LLC resulted in an additional increase in plasma tigecycline concentrations. Chromatography revealed a secondary tigecycline-related peak with a longer retention time than the parent tigecycline peak. PK data are summarized in Tables 8 and 9. When administered at 4.8 mg/kg, the mean _Cmax increased to 0.79 μg/mL (1.11 μg/mL when including the secondary peak) with a mean _Tmax of 17 minutes. The mean AUC _(0-t) was 85.6 μg*min/mL (117.63 μg*min/mL when including Peak 2), resulting in a mean F% of 20.3% (CV, 96.6%; F% including Peak 2 was 27.9%).

Similar to the 100 mM CA experiment, increasing the dose to 9.0 mg/kg resulted in a significant increase in plasma tigecycline. A tigecycline-related peak was also observed in this experiment, but it was not nearly as high as in the lower dose experiments. When administered at 9.0 mg/kg in 400 mM CA (pH 3.5) and 26 mM LLC, the mean _Cmax was 2.49 μg/mL (2.88 μg/mL when Peak 2 was included), occurring at a mean _Tmax of 10 minutes. The mean AUC _(0-t) was 138 μg*min/mL (153 μg*min/mL when Peak 2 was included), resulting in a mean F% of 21.8% (CV, 40.8%; F% including Peak 2 was 24.13%). Figure 3 compares the pooled mean dose-adjusted data from Studies RA851 and RA853 for the different formulations studied.

Table 6. Plasma Concentrations and Pharmacokinetics of Tigecycline in Sprague-Dawley Rats Following a Single ID Injection of Tigecycline Formulated in PBS

^* Mean PK parameters do not include animal RA853-6, and due to the death of RA853-5, mean reported plasma concentrations represent animal RA853-4.

Since those surgeries were performed separately on the same day, the F% for the 4.8 mg/kg dose was calculated relative to the data for 0.64 mg/kg IV, while the F% for the 9.0 mg/kg dose was calculated relative to the data for 12 mg/kg IV.

Table 7. Plasma concentrations and pharmacokinetics of tigecycline in Sprague-Dawley rats following a single ID injection of tigecycline formulated in 100 mM CA (pH 3.5), 26 mM LLC

Since those surgeries were performed separately on the same day, the F% for the 4.8 mg/kg dose was calculated relative to the data for 0.64 mg/kg IV, while the F% for the 9.0 mg/kg dose was calculated relative to the data for 12 mg/kg IV.

Table 8. Plasma Concentrations and Pharmacokinetics of Tigecycline in Sprague-Dawley Rats Following a Single ID Injection of Tigecycline Formulated in 400 mM CA (pH 3.5), 26 mM LLC (Using Tigecycline Mother Peak Only)

Since those surgeries were performed separately on the same day, the F% for the 4.8 mg/kg dose was calculated relative to the data for 0.64 mg/kg IV, while the F% for the 9.0 mg/kg dose was calculated relative to the data for 12 mg/kg IV.

Table 9. Plasma Concentrations and Pharmacokinetics of Tigecycline (Including Tigecycline-Related Peaks) in Sprague-Dawley Rats Following a Single ID Injection of Tigecycline Formulated in 400 mM CA (pH 3.5), 26 mM LLC

Since those surgeries were performed separately on the same day, the F% for the 4.8 mg/kg dose was calculated relative to the data for 0.64 mg/kg IV, while the F% for the 9.0 mg/kg dose was calculated relative to the data for 12 mg/kg IV.

Mechanistic Feasibility Assessment (RA861, RA867, RA869)

Positive data from the preliminary feasibility study necessitated an examination of the individual contributions of each active excipient (CA and LLC). Therefore, additional studies were conducted to compare the F% and PK profiles of tigecycline administered formulated in one of each active excipient (RA861 and RA869) with the highest F% formulation from the preliminary feasibility study (400 mM CA (pH 3.5) and 26 mM LLC from studies RA851 and RA853). Additional studies were conducted to explore the effect of formulation pH at constant CA and LLC concentrations (RA867).

RA861 was designed with three ID injection arms, 400 mM CA (pH 3.5) and 26 mM LLC as a control, 400 mM CA (pH 3.5) alone, and a third arm formulated with 26 mM LLC alone. Results showed very low exposure compared to the initial feasibility study, and it is believed that an issue originated from the analytical method. These issues necessitated Study RA869, which was essentially a repeat of RA861, but with an IV comparator replacing the CA arm alone. In short, both studies demonstrated the utility of CA as a viable excipient for tigecycline. The PK data from Study RA869 replicated the F% of approximately 22% when dosed in 400 mM CA (pH 3.5) and 26 mM LLC (RA851 and RA853), while dosing with 26 mM LLC alone produced an average F% of 9%.

Study RA867 compared the %F and PK of tigecycline when administered in formulations with varying pH. The study included two formulation arms, with six rats each dosed ID with 400 mM CA and 26 mM LLC at either pH 3.5 or pH 6.0. Data showed that rats dosed with the pH 3.5 formulation exhibited a higher C _max , earlier T _max , and higher AUC _{(0-t )} . These data suggest the importance of pH, rather than calcium masking, as the primary mechanism behind the functionality of CA, a small molecule that can be used as an excipient.

Table 10. Summary of mean tigecycline pharmacokinetic parameters in female Sprague-Dawley rats using different pH, CA and/or LLC content (CV%)

Preliminary Feasibility Study (RA851, RA853)

These studies demonstrate the feasibility of improving oral F% of tigecycline (BCS class III antibiotic) using a combination of citrate buffer (pH 3.5) and LLC in an anesthetized rat model. Intraduodenal administration was used to simulate administration of enteric-coated dosage forms in larger mammals. Neither these preliminary feasibility studies nor the mechanistic studies discussed below were designed to explore whether enteric coating of the dosage form is necessary for small molecules. From a theoretical perspective, considering the mechanism of permeation, it seems that enteric coating should be preferred from a variable perspective because it would limit potential food and dilution effects.

Intravenous administration of tigecycline resulted in the expected biphasic, first-order plasma concentration curve. Given the variable and relatively low tigecycline plasma concentrations observed during the distribution phase of ID-administered tigecycline in study RA851 (Figures 7 and 10), the study was repeated at a higher dose (RA853). From a theoretical perspective, one way to overcome the low exposure associated with administration of BCS Class III compounds is to increase the local concentration available for absorption (i.e., dose). Consistent with a passive absorption mechanism, when total exposure depends directly on dose, the dose-adjusted PK curves are nearly superimposable (Figures 3, 9, 12, and 15).

For small molecule therapeutics, where the acidifying activity of CA is generally not required to inhibit metabolic enzymes, we hypothesize that CA would still be beneficial as a viable excipient for certain BCS compounds. Indeed, the absolute tigecycline F% also depended on the concentration of CA, suggesting its potential utility as a solubility excipient (only in this specific case) and permeation enhancer. Tetracycline analogs are known to interact with bile salts in the presence of calcium ions, resulting in complex precipitation. Citric acid can disrupt these interactions by complexing calcium, or by acidifying the environment, thereby disrupting these bile salt interactions and making the active ingredient available for absorption. When formulated with 100 mM CA (pH 3.5) and 26 mM LLC, the absolute tigecycline F% was approximately 11%, which increased to approximately 22% when formulated with 400 mM CA (pH 3.5) and 26 mM LLC (Table 11 and Figure 16).

Table 11. Summary of Mean Tigecycline Pharmacokinetic Parameters (CV%) in Female Sprague-Dawley Rats

*F% was calculated compared to the respective IV arm of each study.

It should be emphasized that the data presented in Table 11 for tigecycline formulated in 400 mM CA (pH 3.5) and 26 mM LLC are for tigecycline only. Upon analysis, it was noted that for two studies, RA851 and RA853, the chromatography of plasma samples from this formulation showed a rather significant peak with a retention time longer than the tigecycline peak. This unknown peak (referred to as the tigecycline-related peak) was not observed in the time zero plasma samples of the individual animals, but was observed at all subsequent time points, and its levels were equivalent to/followed the levels of tigecycline. It is hypothesized that this peak may be a degradation product of tigecycline, perhaps a citrate adduct, since there was some storage time between sample collection and subsequent analysis, although this peak has not yet been identified. Further supporting the degradation theory is that this peak was not observed in the mechanistic studies discussed below (particularly RA867 or RA869), where the storage time was the shortest. However, given that this peak has not yet been identified, it is not included in the overall summary. Inclusion of this peak resulted in an absolute F% of approximately 28% in RA851 and approximately 24% in RA853 (Table 9).

Interestingly, when the IV versus ID PK curves are compared, the distribution phases of the curves differ significantly (Figure 20). Given the slower distribution (higher percentage of initial relative time), it can be speculated that bioavailability is underestimated due to limited sample collection time. Further studies are needed to determine why the distribution of tigecycline is slower with ID administration than with IV. Given the reported high steady-state volume of distribution for tigecycline, one could propose preferential tissue distribution, but this is clearly speculation. It will be interesting to see if this finding is replicated in the canine model, especially given the differences in hepatic and biliary anatomy and function in rats and dogs.

Mechanistic Feasibility Assessment (RA861, RA867, RA869)

Positive data from the preliminary feasibility study necessitated an examination of the individual contributions of each active excipient (CA and LLC). Therefore, additional studies were conducted to compare the F% and PK profiles of tigecycline formulated in one of each active excipient (RA861 and RA869) with the highest F% formulation in the preliminary feasibility study (400 mM CA (pH 3.5) and 26 mM LLC from studies RA851 and RA853). An additional study was conducted to explore the effect of formulation pH at constant CA and LLC concentrations (RA867).

Studies designed to assess the relative individual contributions of CA and LLC (RA861 and RA869) demonstrated the utility of CA as a viable excipient for oral formulations of tigecycline. Excluding potential analytical method issues, the results of study RA869 replicated the relatively high absolute F% (22%) when formulated in 400 mM CA (pH 3.5) and 26 mM LLC, but also showed an absolute tigecycline F% of 9% when administered in 26 mM LLC alone (no CA; Table 10). These studies not only support the simultaneous use of CA and LLC but also provide further avenues for investigating the observed synergistic effects of the combination.

To this end, study RA867 was conducted to determine whether the effects of CA were truly due to the physicochemical properties of citrate or to the low pH. This study compared the F% and PK of tigecycline when administered in a formulation of the same components (400 mM CA, 26 mM LLC) at pH 3.5 or pH 6.0. The data showed that rats dosed with the pH 3.5 formulation displayed a higher C _max , earlier T _max , and higher AUC _(0-t) . These data suggest the importance of pH, rather than calcium masking, as the primary mechanism behind the function of CA, a small molecule, as a viable excipient. Additional studies that eliminate potential confounding factors are needed to fully elucidate the utility of the acidic pH of this compound. For example, other studies have demonstrated the effect of environmental acidification on enhanced permeability, a known mechanism of increased permeability. In this case, acidification has the additional benefit of disrupting the tigecycline-bile salt complex. Although higher pH citrate would be a better calcium complexing agent (reported pKa of 3.1, 4.7, and 6.4), this citrate would still disrupt the tigecycline-bile salt interaction and increase permeation, and it is unclear how much effective calcium complexing is required to disrupt the bile salt interaction. In short, the observed differences in F% are simply a function of insolubility.

The studies presented in Example 1 demonstrate embodiments of the drugs used in the pharmaceutical compositions of the present invention, wherein the pharmaceutical compositions are for oral delivery of BCS class III small molecules. The absolute F% of tigecycline delivered by ID injection and formulated in PBS was 1.6% at a low dose (RA851) and 2.8% at a high dose (RA853). When tigecycline was formulated in 100mM CA (pH 3.5) and 26mM LLC, the absolute F% increased to about 11%. Increasing the CA content to 400mM (pH 3.5) and containing 26mM LLC resulted in an increase in the absolute F% to about 22%. Additional mechanistic studies described in Example 1 demonstrated the synergistic effect of the two functional excipients and the importance of the pH of the formulation in enhancing the oral F% of tigecycline.

Example 2. Administration of Zanamivir in Rats

Material

animal

Naive female Sprague-Dawley rats (Taconic Farms, Germantown, NY) were housed in groups of two with food and water available ad libitum. Animals weighed approximately 250 g at the time of testing. Rats were fasted overnight (water was available) prior to dosing.

Test and control articles

The information of the test article zanamivir is listed in Table 12.

Table 12. Test product information

project Compound name supplier Supplier batch/lot number

Test product Zanamivir MedChem Express CS-0631-05684

carrier

A stock solution of zanamivir was prepared by dissolving zanamivir in 2N HCl to a concentration of 40 mg/mL immediately before use. Aliquots of this stock solution were diluted into the indicated formulations.

method

Preparation and administration of the drug

Rats (n=3) were administered a 0.16 mg dose of zanamivir IV via an indwelling carotid catheter in a volume of 400 μL. Blood samples were collected from the carotid artery before dosing and at 5, 10, 20, 30, and 60 minutes after test article administration.

Rats (n=3 per formulation) were given a 300 μL bolus (1.2 mg zanamivir) per formulation via ID injection 5 cm from the pyloric junction. Blood samples were collected from the carotid artery before dosing and at 10, 20, 30, 60, 120, and up to 180 minutes after test article administration.

All blood samples were treated with 20 μL of 180 mM EDTA and then centrifuged at 3000 rpm for 5 minutes. Plasma was collected, frozen at -20°C, and then shipped on dry ice to Absorption Systems for analysis.

Table 13. Formulations of Zanamivir

^1Solvent is phosphate buffered saline

^2. The solvent is deionized water

^3. Dilute from a 40 mg/mL zanamivir stock solution in 2N HCl

⁴ Dilute from 2M citric acid stock solution (pH 3.5)

⁵ Dilute from a 20% w/v stock solution of LLC in water

Animal Procedure for Zanamivir Plasma Concentrations

Plasma samples were analyzed by an absorbance system using a quantitative LC-MS/MS assay to determine the plasma concentration of zanamivir.

Calculation of bioavailability

The AUC of the plasma zanamivir concentration versus time curve was calculated using trapezoidal integration in Microsoft Excel. The absolute bioavailability was calculated according to the following equation:

Where D ^ID is the ID dose (mg) divided by the weight of each individual rat (kg), and D ^IV is the IV dose (mg) divided by the average weight of rats in the IV arm (kg).

result

Individual zanamivir plasma concentrations for the six formulations studied are listed below. The mean PK profile is shown in Figure 27 and the PK data for each formulation are summarized in Table 14.

Table 14. Summary of PK Data by Dosage Form

Since zanamivir stock solutions were prepared in 2N HCl to dissolve the API, all carriers were acidic. This resulted in enhanced absorption of zanamivir for all formulations. However, the carrier with the best bioavailability relative to the others was formulation "C," containing 400 mM CA and 1.0% LLC.

Table 15. Plasma Concentrations of Zanamivir (ng/mL): IV Formulation

Table 16. Plasma Concentrations of Zanamivir (ng/mL): Formulation A

Table 17. Plasma Concentrations of Zanamivir (ng/mL): Formulation PBS

Table 18. Plasma Concentrations of Zanamivir (ng/mL): Formulation B

Table 19. Plasma Concentrations of Zanamivir (ng/mL): Formulation C

Table 20. Plasma Concentrations of Zanamivir (ng/mL): Formulation D

Table 21. Summary of Example 2 Formulations Tested

^1Solvent is phosphate buffered saline

^2. The solvent is deionized water

^3. Dilute from a 40 mg/mL stock solution of zanamivir in 2N HCl

⁴ Dilute from 2M citric acid stock solution (pH 3.5)

⁵ Dilute from a 20% w/v stock solution of LLC in water

Each of the five ID formulations was administered to rats at a dose of 1.2 mg (4.8 mg/kg) by direct bolus injection into the duodenum, while the IV formulation was injected at a dose of 0.16 mg (0.64 mg/mL) via an indwelling carotid artery catheter. Blood samples were collected from the carotid artery before and at predetermined time points after dosing to determine the plasma concentration of zanamivir by LC-MS/MS analysis.

Table 22. Summary of bioavailability by formulation

Since zanamivir stock solutions were prepared in 2N HCl to dissolve the API, all carriers were acidic. This resulted in increased absorption of zanamivir for all formulations. However, the carrier with the best bioavailability relative to the others was formulation "C," containing 400 mM CA and 1.0% LLC.

Example 3: Administration of aminoglycosides in dogs

Material

animal

Adult beagle dogs weighing approximately 10 to 15 kg were used in the study. The animals were housed individually or in pairs in a large kennel (located at the Sinclair Research Center, Columbia, MO). Primary enclosures were as specified in the USDA Animal Welfare Act (9 CFR Parts 1, 2, and 3) and as described in the Guide for the Care and Use of Laboratory Animals (National Academy Press, Washington, DC, 1996). A photoperiod of 12 hours light/12 hours dark was maintained. Room temperature was set to maintain 20 ± 5°C. Relative humidity was monitored but not controlled. Animal rooms and enclosures were cleaned according to the testing facility (Sinclair) SOP.

Certified dog food was provided once daily in an amount appropriate for the size and age of the animal (-400 g). Tap water was available ad libitum via an automatic watering device or a water bowl.

Animals were fasted overnight before dosing and throughout the blood collection period.

Table 23: Test product information

Experimental Project Batch/lot number supplier Kanamycin 5023 Spectrum,Amresco Tobramycin 110M1191V Sigma Aldrich

carrier

For IV studies, kanamycin and tobramycin were prepared as concentrated solutions in PBS and shipped frozen to the Sinclair Research Center, where the concentrated solutions were diluted in PBS and filter sterilized before administration. For oral studies, kanamycin and tobramycin were mixed with other excipients and transferred to capsules.

method

Dosage and route of administration

Kanamycin was administered as a 0.1 mg/mL bolus to each of three beagle dogs. Tobramycin was administered as a 0.1 mg/mL bolus to each of three beagle dogs. The formulation compositions and dosing details are summarized in Table 24.

Table 24. IV Formulations and Dosages

Oral administration of the capsules was accomplished by administering the capsule to the back of each dog's mouth. Kanamycin was delivered in DRCAPS ^™ or VCAPPLUS ^™ capsules (both from Capsugel). DRCAPS ^™ offers acid resistance and does not require coating. VCAP PLUS ^™ capsules are vegetarian HPMC capsules. The formulation compositions and dosing details of the kanamycin capsules are summarized in Table 25.

Table 25. Kanamycin capsule composition, coating, and number of dogs

¹ Up to 6% weight gain was obtained using Eudragit 7 L30-D55.

Tobramycin was delivered in enteric-coated VCAP PLUS ^™ capsules. Details of the formulation composition and dosing are summarized in Table 26.

Table 26: Tobramycin Capsule Composition, Coating, and Number of Dogs

¹ Up to 6% weight gain was obtained using Eudragit 7 L30-D55.

Study design and plasma sample collection

In the oral and IV studies, adult female beagle dogs weighing 9-15 kg were used. Dogs were fasted overnight before the start of each study but were allowed free access to water. On the study day, a 3 mL pre-dose blood sample was collected from each animal. Subsequently, each group of animals was given a single capsule containing either kanamycin or tobramycin mixed in the specified formulation.

After drug administration, 3 mL blood samples were collected from the brachial vein at various time points up to 240 minutes (4 hours) after administration. Blood samples were collected in new heparinized monovette sampling syringes. The samples were placed on ice and then centrifuged at approximately 2750 rpm for 10 minutes at 2-8°C. Each tube was labeled with the dog ID# and time point and stored at -20°C pending shipment.

Analytical Procedure for Kanamycin and Tobramycin

According to the "ELISA for Kanamycin Detection", a competitive ELISA kit from UC Biodevices (Nanmen, CA) was used to determine plasma kanamycin and tobramycin concentrations. For the determination of kanamycin blood levels, the standard for kanamycin from this kit was used for a standard curve. For the determination of tobramycin blood levels, tobramycin from Sigma-Aldrich was diluted and used for a standard curve. The standard curve range for kanamycin was 0.2 ng/mL to 3.0 ng/mL. The standard curve range for tobramycin was 0.1 ng/mL to 5.0 ng/mL. Plasma samples were appropriately diluted with the kit assay buffer.

Kanamycin and Tobramycin ELISA calculation

Mean plasma concentrations of kanamycin and tobramycin were calculated using 5-parameter curve fitting in SOFTMAX ^™ Pro software, version 5.0.1 (Molecular Devices).

Pharmacokinetic data processing

The kanamycin and tobramycin concentration-time data for each animal were analyzed using the PK function of Microsoft Excel by a non-compartmental approach. Maximum plasma concentration ( _Cmax ) values and their time of occurrence ( _Tmax ) were directly obtained from the plasma concentration versus time curve. The area under the plasma concentration-time curve ( _AUClast ) was estimated by the linear trapezoidal rule from time zero to the time of the last observed plasma concentration.

result

Individual plasma concentrations of kanamycin and tobramycin at each sampling time, and the corresponding PK parameters, are presented in Tables 27 to 38. The mean concentration-time profiles of kanamycin and tobramycin following IV administration are shown in Figures 28 and 29, respectively.

Plasma kanamycin after IV administration

The _Cmax (SC434) of plasma kanamycin after IV administration was 50 ng/mL, observed at a mean time ( _Tmax ) of 5 minutes (Table 27). The mean concentration curve of kanamycin after IV administration is shown in FIG28.

Table 27: Plasma Concentrations and Pharmacokinetics of Kanamycin in Beagle Dogs Following a Single IV Bolus Injection

Plasma tobramycin after IV administration

The _Cmax (SC435) of plasma tobramycin after IV administration was 31 ng/mL, observed at a mean time ( _Tmax ) of 5 minutes (Table 28).The mean concentration curve of tobramycin after IV administration is shown in FIG29.

Table 28: Plasma Concentrations and Pharmacokinetics of Tobramycin in Beagle Dogs Following a Single IV Bolus Dose

Plasma kanamycin after oral administration

Results of oral administration of kanamycin in unformulated, uncoated VCAP PLUS ^™ capsules (SC432) containing only PROSOLV ^™ (formulation JSV003-038) are shown in Table 29. All dogs showed a low level of bioavailability, averaging 2.8%. The curves for individual dogs are shown in Figure 30.

Table 29. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of PROSOLV ^™ in uncoated capsules (Formulation JSV003-038)

The addition of CA and LLC to the uncoated capsules resulted in a significantly higher mean bioavailability (SC432) of 12.4%. The results for the individual dogs are shown in Table 30. The curves for the individual dogs are presented in Figure 31.

Table 30. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose in uncoated capsules formulated with CA and LLC (Formulation JSV-003-039).

Enteric-coated VCAP PLUS ^™ capsules containing 100 mg LLC were prepared with varying concentrations of CA to examine the effect of CA content on kanamycin bioavailability. Formulation JSV-003-005 (SC426) contained 500 mg CA and yielded an average bioavailability of 14.2%. The plasma results for individual dogs are shown in Table 31, and the absorption curves for individual dogs are shown in Figure 32.

Table 31. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of capsules containing 500 mg CA (formulation JSV-003-005)

Formulation JSV-003-052 (SC438) contained 250 mg CA and yielded a mean bioavailability of 11.4%.The plasma results for individual dogs are shown in Table 32 and the absorption curves for individual dogs are shown in Figure 33.

Table 32. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of capsules containing 250 mg CA (formulation JSV-003-052)

Formulation JSV-003-053 (SC438) contained 100 mg CA and yielded a mean bioavailability of 12.4%.The plasma results for individual dogs are shown in Table 33 and the absorption curves for individual dogs are shown in Figure 34.

Table 33. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of capsules containing 100 mg CA (formulation JSV-003-053)

Formulation JSV-003-054 (SC438) contains 50 mg of CA. Only one of the three dogs dosed showed detectable blood levels of kanamycin, with an average bioavailability of 2.6%. The plasma results for the individual dogs are shown in Table 34, and the absorption curves for the individual dogs are shown in Figure 35.

Table 34. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of capsules containing 50 mg CA (formulation JSV-003-054)

For the bioavailability of kanamycin, the use of DRCAPS ^™ was investigated instead of enteric-coated VCAP PLUS ^™ . Two studies were conducted using DRCAPS ^™ , SC426 and SC433. In the first study (formulation JSV-003-010), DRCAPS ^™ contained 500 mg CA and 100 mg LLC. The average bioavailability was 9.2%, and the individual plasma kanamycin concentrations are shown in Table 35. The individual plasma absorption curves are shown in Figure 36.

Table 35. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of capsules containing 500 mg CA and 100 mg LLC in DRCAPS ^™ (formulation JSV-003-010).

The second study using DRCAPS ^™ (formulation JSV-003-041) contained 250 mg CA and 100 mg LLC. The mean bioavailability was 10.6%, and the individual plasma kanamycin concentrations are shown in Table 36. The individual plasma absorption curves are shown in Figure 37.

Table 36. Plasma concentrations and pharmacokinetics of kanamycin in beagle dogs following a single oral dose of capsules containing 250 mg CA and 100 mg LLC in DRCAPS ^™ (formulation JSV-003-041).

Plasma tobramycin after oral administration

The results of oral administration of tobramycin in unformulated VCAP PLUS ^™ capsules containing only PROSOLV ^™ (formulation JSV-003-050) are shown in Table 37. The average bioavailability was 0.2%; only three of eight dogs showed detectable tobramycin blood levels. Individual plasma curves are shown in Figure 38.

Table 37. Plasma Concentrations and Pharmacokinetics of Tobramycin in Beagle Dogs Following a Single Oral Dose in PROSOLV ^™ (Formulation JSV-003-050)

After adding CA and LLC, the average bioavailability of 8 dogs increased to 15%. All dogs given formulation JSV-003-051 showed blood levels of tobramycin. The PK results are shown in Table 38 and the individual plasma curves are shown in Figure 39.

Average oral absorption profile of kanamycin

A comparison of the mean absorption profiles for dogs of kanamycin administered in DRCAPS ^™ (JSV-003-010) and VCAP PLUS ^™ (JSV-003-005) capsules is shown in Figure 40. Both groups of capsules contained the same key excipients (500 mg CA and 100 mg LLC), with the only difference being the capsules themselves. The data for each group of capsules were adjusted for mean _Tmax . Error bars represent standard error of the mean (SEM).

A comparison of the mean absorption curves for kanamycin in dogs administered unformulated (0 mg CA and 0 mg LLC) VCAP PLUS ^™ (JSV-003-038) and formulated (500 mg CA and 100 mg LLC) VCAP PLUS ^™ (JSV-003-039) capsules is shown in Figure 41. Both groups of capsules were uncoated. The data for each group of capsules were adjusted for mean _Tmax . Error bars represent SEM.

A comparison of the mean absorption curves of kanamycin in dogs administered with VCAP PLUS ^™ capsules containing 100 mg LLC and varying concentrations of CA (500 mg CA, JSV-003-005; 250 mg CA, JSV-003-052; 100 mg CA, JSV-003-053; 50 mg CA, JSV-003-054) is shown in Figure 42. The data for each group of capsules are adjusted for mean _Tmax . Error bars represent SEM.

Average oral absorption profile of tobramycin

A comparison of the mean absorption profiles of dogs administered tobramycin in unformulated (0 mg CA and 0 mg LLC, JSV-003-050) and formulated (500 mg CA and 100 mg LLC, JSV-003-051) VCAP PLUS ^™ capsules is shown in Figure 43. The data for each group of capsules were adjusted for mean _Tmax . Error bars represent SEM.

discuss

Using the pharmaceutical compositions of the present disclosure, an oral bioavailability of 14% for kanamycin and 15% for tobramycin was achieved. The key excipients were CA and LLC. In Example 3, a concentration of at least 100 mg of CA was used in the pharmaceutical composition. In this example, VCAP PLUS ^™ capsules were preferred over DRCAPS ^™ capsules in the pharmaceutical composition. The studies described in Example 3 serve as examples of BCS Class III aminoglycoside antibiotics. The examples of kanamycin and tobramycin are not intended to be limiting, but rather serve as examples of how the pharmaceutical compositions of the present disclosure can improve the oral bioavailability of BCS Class III molecules.

A feasibility study was conducted to evaluate the oral bioavailability and pharmacokinetics (PK) of BCS class 3 aminoglycoside bacterial antibiotics (kanamycin and tobramycin).The study design consisted of one intravenous (IV) phase and several oral phases of administration in beagle dogs.

Kanamycin oral administration in enteric-coated Vcap Plus capsules (preparation JSV-003-005) comprising 500mg citric acid (CA) and 100mg lauroyl-L-carnitine (LLC) was given to 4 dogs, and blood samples were collected over 4 hours to determine the plasma kanamycin concentration over time. The dogs showed an average _Cmax of 428ng/mL and an average absolute bioavailability of 14%. Tobramycin oral administration in enteric-coated Vcap Plus capsules (preparation JSV-003-051) comprising the same excipients was given to 8 dogs, and blood samples were collected over 4 hours to determine the plasma tobramycin concentration over time. These dogs showed a similar average _Cmax of 314ng/mL and a similar average absolute bioavailability of 15%.

Table 39. Summary of mean pharmacokinetic parameters (± SEM) of kanamycin and tobramycin following oral administration of Vcap Plus coated capsules to beagle dogs

Pharmacokinetic studies were conducted in dogs using coated and uncoated capsules containing kanamycin formulated with varying amounts of CA. The oral bioavailability of kanamycin for uncoated capsules formulated without CA and LLC was 2.8%, while the bioavailability of kanamycin for uncoated capsules formulated with 500 mg of CA and 100 mg of LLC was 12.4%. There was no significant change in the bioavailability of kanamycin delivered orally using enteric-coated capsules containing the same formulation. Furthermore, there was essentially no difference in bioavailability when the CA level was reduced to 100 mg. Reducing the amount of CA to 50 mg reduced the bioavailability of kanamycin to 2.6%.

Table 40. Summary of Mean Pharmacokinetic Parameters of Kanamycin Following Oral Administration of Vcap Plus (Coated and Uncoated) Capsules to Beagle Dogs (± SEM)

¹ Only one of the three dogs showed detectable blood levels.

A study was also conducted using DRCAPS ^™ containing 10 mg kanamycin, 100 mg LLC, and two concentrations of CA. These dogs did not show high levels of oral bioavailability. The results of these two studies are presented below.

Table 41. Summary of mean pharmacokinetic parameters of kanamycin following oral administration of DR capsules to beagle dogs (± SEM)

A summary of tobramycin studies comparing unformulated (0 mg CA and 0 mg LLC) and formulated (500 mg CA and 100 mg LLC) VCAP PLUS ^™ capsules is as follows: As expected based on similar molecular weight and structure, the oral bioavailability of tobramycin was 15%, similar to that of kanamycin.

Table 42. Summary of Mean Pharmacokinetic Parameters of Tobramycin Following Oral Administration of Enteric-Coated VCAP PLUS ^™ Capsules to Beagle Dogs (Mean Data (± SEM) Shown)

¹ Only three of the eight dogs responded with detectable blood levels.

Example 4: Tigecycline in dogs

Material

Animals and test subjects

Adult beagle dogs weighing approximately 9 to 15 kg were used in the study. The animals were housed individually or in pairs in a large kennel (located at the Sinclair Research Center, Columbia). The primary enclosures were as specified in the USDA Animal Welfare Act (9 CFR Parts 1, 2, and 3) and as described in the Guide for the Care and Use of Laboratory Animals (National Academy Press, Washington, D.C., 1996). A photoperiod of 12 hours light/12 hours dark was maintained. Room temperature was set to maintain 20 ± 5°C. Relative humidity was monitored but not controlled. Animal rooms and enclosures were cleaned according to the experimental institution (Sinclair) SOP.

TEKLAD ^™ certified dog food was provided once daily in an amount appropriate for the animal's size and age (~400 g). Tap water was available ad libitum via an automatic watering device or a water bowl. Animals were fasted overnight prior to dosing and throughout the blood collection period. Information on the test article, tigecycline, is listed in Table 43.

Table 43. Test product information

project Compound name Catalog Number Batch/lot number supplier Test product Tigecycline S-1403 S140301 Selleck Chemical Co.

method

Dosage and route of administration

Doses are expressed based on free net tigecycline content. Tigecycline was administered intravenously as a bolus at a dose of 1.0 mg/mL. Oral administration of the enteric-coated capsules was achieved by administration to the back of the dog's mouth, followed by an additional 5 mL of water to ensure swallowing. Details of the doses and formulation compositions for the preliminary feasibility evaluation are summarized in Table 43.

Table 44. Capsule composition, dosage, and number of dogs ¹ _, ²

¹ Calculate capsule composition by multiplying the average powder content by the percentage of each component in the powder mix

^2Target dose assumes an average dog weight of 12 kg at the time of dosing

^3. Citric acid DC F20, Jungbunzlauer, Unigene lot #AF659

^4- Lauroyl-L-carnitine, custom synthesis, Lonza, Unigene lot #AF946

⁵ PROSOLV ^™ SMCC HD90, JRS Pharma, Unigene batch #AF602

Study design and sample collection

Adult female beagle dogs weighing 9-15 kg were used in both oral and IV studies. Dogs were fasted overnight prior to the start of each study. Water was provided ad libitum. On the study day, a 3 mL pre-dose blood sample was collected from each animal. Subsequently, each group of animals was dosed according to the protocol, either IV or PO via capsule.

After drug administration, 3 mL blood samples were collected from the brachial vein at various time points up to 1140 minutes (24 hours) after administration, depending on the duration of the study. Blood samples were collected in new heparinized monovette sampling syringes. The samples were placed on ice and then centrifuged at approximately 2750 rpm for 10 minutes at 2-8°C. Each tube was labeled with dog ID# and time point and stored at -20°C awaiting transport.

Analytical Procedure for Tigecycline

Quantitative determination of tigecycline in canine plasma was performed using an HPLC assay with UV detection at 350 nm. Minocycline (VWR international) was used as an internal standard. Sample processing/cleanup of plasma samples was performed offline by protein precipitation in acetonitrile acidified with 0.5% trifluoroacetic acid (TFA).

The HPLC system consisted of a Shimadzu SIL-HTc HPLC system equipped with dual Shimadzu LC-10ADvpisopump pumps, a Shimadzu CTO-10ASvp column temperature controller, and a Shimadzu SPD-10Avp variable wavelength detector. Chromatographic separation was based on Li et al., with some notable differences (see Li et al., 2004, Quantitation of tigecycline, a novel glycylcycline, by liquid chromatography. J Chromatography B. 811: 225-229). HPLC separation was performed on a reverse phase column (Phenomenex Luna Cl8(2), 5 μm, 150×4.6 mm, part number: 00F-4252-E0) using an initial isocratic phase followed by a gradient elution of tigecycline. Mobile phase A is composed of 23mM phosphate buffer (pH 2.5) and 4mM 1-octanesulfonic acid, while mobile phase B is composed of 90% acetonitrile, 10% water and 2mM 1-octanesulfonic acid. The time program starts with an isocratic elution of 25% mobile phase B for 6 minutes, followed by a linear increase of mobile phase B to 35% (14 minutes) over the next 8 minutes, and then re-equilibrated to 25% mobile phase B for another 4 minutes. The total run time is 18 minutes for each sample. The flow rate of the mobile phase is 1.2mL/min. Detection is performed using an SPD-10Avp variable wavelength detector set at 350nm with a sensitivity of 0.001aufs.

Unknown samples and calibration standards (tigecycline in pooled canine plasma) were processed by protein precipitation with acidified (0.5% TFA v/v) acetonitrile spiked with internal standard. The samples were then centrifuged at 13k rpm for 5 minutes under refrigerated conditions. The supernatant was removed and the liquid was removed to dryness in a turbovap under nitrogen atmosphere. The dried extract was reconstituted in 60 μL of mobile phase A and the suspension was further centrifuged at 5k rpm for 5 minutes to precipitate any insoluble material. The resulting supernatant was then injected into the LC.

Unknown concentrations in canine plasma samples were determined by interpolating the peak area ratios of analyte:internal standard to their nominal concentration ratios onto a regression line obtained from calibration standards spiked into pooled canine plasma. Unweighted regression was used for calculations. The method was demonstrated to be linear to 0.05 μg/mL (defined limit of quantitation). The calibration curve covered the range of 0.05 μg/mL to 5 μg/mL.

It should be noted, however, that when the method was transferred to an older HPLC system (equipped with a Shimadzu SCT-10Avp system controller and SIL-10A autosampler), the time program was further altered to a gradient of 38% mobile phase B to accommodate the programming change. All other parameters remained unchanged.

Table 45. RP-HPLC analysis of tigecycline in dog plasma

Pharmacokinetic data processing

Tigecycline PK parameters were calculated for each dog using non-compartmental analysis with the PK function in Microsoft Excel. Maximum plasma concentration ( _Cmax ) values and their time of onset ( _Tmax ) were obtained directly from the plasma concentration versus time curve. The area under the plasma concentration-time curve ( _AUClast ) was estimated using the linear trapezoidal rule by adding the area under the curve ratio of all times from time zero to the last observed plasma concentration.

result

Plasma tigecycline after IV administration (SC427, SC431)

At the target dose of 0.08 mg/kg, the mean _Cmax of plasma tigecycline was 79.1 ng/mL, observed at a mean time ( _Tmax ) of 5 minutes (0.08 hours). As expected based on the reported single-dose half-life of approximately 20 hours in humans, tigecycline was measurable within 4 hours. The mean AUC _(0-t) was 72.4 ng*hr/mL.

When the target dose was increased to 0.42 mg/kg, the mean _Cmax increased to 335 ng/mL, which was also observed at a _Tmax of 5 minutes. In both studies, there was a clear biphasic profile of tigecycline, which was initially very rapid and reached steady state at approximately 30 minutes. The mean AUC _(0-t) was 411 ng*hr/mL.

Table 46. Summary of Tigecycline IV Pharmacokinetic Parameters in Beagle Dogs Administered a Single 1 mg Dose (SC427) Formulated in PBS

*Actual dog weight at study entry was not available. Dog weight was assumed to be 12 kg.

Table 47. Summary of Tigecycline IV Pharmacokinetic Parameters in Beagle Dogs Administered a Single 5 mg Dose (SC431) Formulated in PBS

*Actual dog weight at study entry was not available. Dog weight was assumed to be 12 kg.

Table 48. Summary of Mean Tigecycline IV Pharmacokinetic Parameters (CV%) in Beagle Dogs

Plasma Tigecycline after PO administration (SC424, SC430)

Tigecycline was administered orally in enteric-coated capsules formulated with 500 mg of coated CA (Citrocoat DC F20, Jungbunzlauer), 100 mg of LLC, and silicified microcrystalline cellulose (PROSOLV ^™ ) as a filler, or in unformulated capsules containing only the filler. The capsules were enteric-coated to a 10% weight gain using a standard preclinical protocol. Two studies were conducted. In study SC424, tigecycline was administered to 8 dogs each, either formulated or unformulated, with a target dose of 15 mg. Study SC430 involved administration of 30 mg of formulated (n=5) or unformulated (n=3) tigecycline, and also included an additional 45 mg formulated arm (n=5) to investigate the effect of dose escalation.

Pharmacokinetic data showed no exposure in the 15 mg or 30 mg unformulated arms of studies SC424 or SC430, respectively, while significant exposure was observed in all doses formulated in both studies. Oral administration of 15 mg formulated tigecycline showed an average _Cmax of 75.5 ng/mL, an average AUC _(0-t) of 133 ng*hr/mL, and an average absolute F% of 12.2%. Pharmacokinetic results in single dogs showed a range of approximately 2 to 30 F%. Administration of tigecycline at higher doses and 24-hour plasma sampling showed that both _Cmax and AUC _(0-t) increased with dose. Administration of 45 mg tigecycline resulted in an average _Cmax of 177 ng/mL, an average AUC _(0-t) of 574 ng*hr/mL, and an average absolute F% of 15.5%. Average _Tmax was reproducible in all formulations studied.

Table 49. Summary of Tigecycline Pharmacokinetic Parameters in Beagle Dogs Administered a Single PO 15 mg Unformulated Enteric Coated Capsule (SC424)

*Actual dog weight at study entry was not available. Dog weight was assumed to be 12 kg.

Although the initial study plan indicated N = 8, only 6 dogs were analyzed. Dogs 5202 and 5203 were omitted from the analysis.

Table 50. Summary of Tigecycline Pharmacokinetic Parameters in Beagle Dogs Administered a Single PO 30 mg Unformulated Enteric Coated Capsule (SC430)

*Actual dog weight at study entry was not available. Dog weight was assumed to be 12 kg.

Table 52. Summary of Tigecycline Pharmacokinetic Parameters in Beagle Dogs Administered a Single 30 mg PO Dose of Enteric Coated Capsules (SC430) Formulated with 500 mg CA and 100 mg LLC

*Actual dog weight at study entry was not available. Dog weight was assumed to be 12 kg.

The reported results do not include animal 5256.

F% was calculated from IV PK data generated from Study SC431.

Table 53. Summary of Tigecycline Pharmacokinetic Parameters in Beagle Dogs Administered a Single 45 mg PO Dose of Enteric Coated Capsules (SC430) Formulated with 500 mg CA and 100 mg LLC

*Actual dog weight at study entry was not available. Dog weight was assumed to be 12 kg.

F% was calculated from IV PK data generated from Study SC431.

Table 54. Mean Tigecycline Pharmacokinetic Parameters (CV%) Following Oral Administration in Enteric Coated Capsules

*The reported results do not include animals 5256.

Capsules were formulated to target 500 mg CA and 100 mg LLC.

F% was calculated based on the respective IV arm of the study.

discuss

These studies demonstrate the feasibility of using a combination of CA and LLC to enhance the oral bioavailability of tigecycline, a BCS Class III antibiotic, in beagle dogs. These formulations were delivered in enteric-coated capsules and provide valuable preclinical proof-of-concept to support potential future clinical development. Example 1, conducted in rats using an ID injection model, demonstrates the apparent synergistic effect of the combination of CA and LLC as absorption-enhancing excipients. The studies described in Example 1 also demonstrate the importance of formulation pH in enhancing the oral F% of tigecycline. While valuable from a mechanistic perspective, Example 1 uses a liquid carrier to deliver tigecycline directly to an absorptive surface and is designed specifically to remove the potential confounding factor of solid-liquid transitions (disintegration and dissolution) of solid dosage forms, which are a major factor in enhancing bioavailability and controlling the variability inherent in formulations.

Intravenous administration of tigecycline resulted in the expected biphasic, first-order plasma concentration curve. Considering that one approach to overcoming the low exposure associated with administration of BCS class III compounds is to increase the local concentration available for absorption (i.e., dose), IV PK profiles were determined at two concentrations. While total exposure was directly dependent on dose ( Figures 44 and 45 ), the dose-adjusted PK profiles were essentially identical ( Figure 46 ).

The rat studies (Example 1) also demonstrated the utility of higher CA concentrations in achieving higher tigecycline exposure. In those studies, 400 mM CA (pH 3.5) combined with 26 mM LLC resulted in a bioavailability of approximately 21%. It is hypothesized that CA may act to disrupt potential tetracycline:bile salt interactions that lead to tigecycline precipitation. To this end, these formulations were prepared with a target of 500 mg coated CA, which is at the upper end of the concentration range typically studied (clinical and preclinical). In addition, these studies did not explore the effect of lower CA concentrations, as data from the rat studies would immediately show lower net exposure. However, these studies explored the effect of dose escalation on absolute exposure.

Oral administration of 15 mg (target 1.25 mg/kg) of tigecycline with 500 mg CA and 100 mg LLC resulted in a mean _Cmax of 75.5 ng/mL, a mean AUC _(0-t) of 133 ng*hr/mL, and a mean absolute F% of 12.2%. Administration of 45 mg of tigecycline resulted in a mean _Cmax of 177 ng/mL, a mean AUC _(0-t) of 574 ng*hr/mL, and a mean absolute bioavailability of 15.5%. Mean _Tmax , at approximately 100 minutes, was reproducible across all oral formulations studied. Interestingly, exposure was linear for both _Cmax and AUC, and was less proportional to dose for _Cmax and AUC _(0-4HR) (Table 55). These observations may be a function of the limited absorption window (by design), as the percent difference predicted at the 30 mg dose (based on the results for the 15 mg dose) was lower than that predicted for the 45 mg dose. Another hypothesis could be that other factors, such as bile salts or transporter interactions, are acting to inhibit the absorption flux; that is, as the dose increases, tigecycline is in such excess that there is insufficient CA to inhibit the transporter or to precipitate the complex with bile salts. However, it is more likely that the biopharmaceutical properties of the molecule itself, due to its extensive tissue distribution, lead to the observed saturation effect.

Tigecycline does exhibit high tissue distribution. Combined with the lack of metabolism, the low dose proportionality further suggests inadequate absorption and nonlinear clearance relative to dose. In short, the observed dose relationship is a saturation effect, i.e., decreased clearance relative to increasing dose, which is most likely due to tissue deposition commensurate with the high tissue distribution of tigecycline, which can be confounded by absorption issues at higher doses. Further supporting this speculation is that no significant differences could be gleaned from the dose-adjusted mean plasma curves (Figure 54). A relatively simple way to test this speculation would be to study the dose proportionality following a single oral dose of tigecycline given as a saturable IV infusion. Such a study would also be beneficial for potential further clinical studies, as this can be foreseen as a potential product profile for oral administration of tigecycline.

Table 55. Dose Proportionality of Tigecycline Pharmacokinetic Parameters Following Oral Administration in Enteric-Coated Capsules

*Reported results do not include animals 5256.

Values predicted based on 15 mg results.

Note that the time scale has been adjusted for comparison, with SC424 sampled to 4 hours and SC430 sampled to 24 hours.

These studies demonstrate the feasibility of applying oral delivery technology to the BCS class III small molecule tigecycline in a canine preclinical model. No tigecycline exposure was observed in dogs given 15 mg or 30 mg tigecycline capsules formulated in microcrystalline cellulose filler. Administration of enteric-coated capsules containing 15 mg tigecycline and formulated with 500 mg CA and 100 mg LLC resulted in a mean absolute F% of 12.2%. Increasing dose linearly increased _Cmax and AUC _(0-t) , but exposure was not dose proportional. Mean bioavailability of 45 mg tigecycline formulated with 500 mg citric acid and 100 mg LLC resulted in a mean absolute F% of 15.5%.

The objectives of these studies were to investigate the oral bioavailability (F%) and pharmacokinetic (PK) profile of orally administered tigecycline in beagle dogs. Two studies were conducted, each consisting of an intravenous (IV) phase and an oral phase using enteric-coated capsules containing formulated or unformulated tigecycline. The studies differed in the administered dose and sampling timeframe.

In Study 1 (SC424 and SC427), tigecycline was administered to beagle dogs (n=3) as a 1 mg IV bolus and also in a 15 mg enteric-coated capsule arm. The capsule phase included two formulations, formulated with citric acid (CA) and 3,O-lauroyl-L-carnitine (LLC), or unformulated (n=8 dogs each). Venous blood samples were collected up to 4 hours after dosing to determine plasma tigecycline concentrations over time.

Study 2 (SC430 and SC431) was designed based on feedback from Study 1 and included a higher dose IV arm (5 mg per animal, n=3), as well as 30 mg and 45 mg formulated (n=5 each) enteric-coated capsules and 30 mg unformulated (n=3) enteric-coated capsules. The study also included 24-hour intravenous sampling to fully characterize the PK profile of the single oral dose. The formulated arms in both studies contained 500 mg CA and 100 mg LLC, while the unformulated arms contained the drug dispersed in microcrystalline cellulose filler. There were no changes in these parameters between Study 1 and Study 2.

Pharmacokinetic data demonstrated that IV administration of tigecycline exhibited biphasic clearance, with approximately proportional increases in both _Cmax and AUC _(0-t) following increasing doses (1 mg vs. 5 mg) between Study 1 and Study 2. The mean _Cmax was 79 ng/mL and 335 ng/mL, respectively, and the mean AUC _(0-t) was 72.4 ng*hr/mL and 411 ng*hr/mL, respectively.

Table 56. Summary of Mean Tigecycline IV Pharmacokinetic Parameters in Beagle Dogs (CV%)

Research Dosage (mg) N Study 1 (SC427) 1 3 79.1(14.1) 5(0) 72.4(32.7) Study 2 (SC431) 5 3 335(25.2) 5(0) 411(54.7)

Oral administration of tigecycline formulated with microcrystalline cellulose (unformulated) and filled into enteric-coated capsules at 15 mg (Study 1) or 30 mg (Study 2) did not result in observable plasma exposure, whereas tigecycline formulated with 500 mg CA and 100 mg LLC demonstrated significant exposure at all doses in both studies. Oral administration of 15 mg of tigecycline formulated with active excipients was given to 8 dogs, and plasma was sampled 4 hours after dosing. The results showed a mean _Cmax of 75.5 ng/mL, a mean AUC _(0-t) of 133 ng*hr/mL, and a mean absolute F% of 12.2%. Administration of tigecycline at higher doses and plasma sampling over 24 hours showed that both _Cmax and AUC _(0-t) increased with dose, but exposure was less proportional to dose, likely due to the limited absorption window of the design. Dosing with 45 mg of tigecycline resulted in a mean _Cmax of 177 ng/mL, a mean AUC _(0-t) of 574 ng*hr/mL, and a mean absolute F% of 15.5%. The mean _Tmax was reproducible across all doses studied.

Table 57. Mean Tigecycline Pharmacokinetic Parameters (CV%) Following Oral Administration in Enteric Coated Capsules

*Reported results do not include animals 5256.

Capsules were formulated to target 500 mg CA and 100 mg LLC.

F% was calculated based on the respective IV arm of the study.

Example 5: Solubility of fenofibrate

method

Fenofibrate is a BCS class II compound and is therefore insoluble in water. Its solubility is 1 mg/mL in ethanol, 30 mg/mL in DMF, 15 mg/mL in DMSO, and 250 mg/mL in 1:3 DMF:PBS (pH 7.2).

The solubility of fenofibrate in water was evaluated at increasing concentrations of LLC from 0.0% w/v to 10.0% w/v. Excess fenofibrate was weighed into a separate PP bottle. The fenofibrate-containing solution was mixed at 125 rpm at 25°C for 4 days. Dissolved fenofibrate was monitored by HPLC against a standard curve prepared in pure _CH3CN .

Results and discussion

The data shown in Figure 57 show that the solubility of fenofibrate in water increases with increasing LLC concentration. The increased solubility of fenofibrate may indicate the utility of LLC in increasing the solubility of other class II molecules in water. LLC can be used as a solubility enhancer in the compositions of the present disclosure.

Claims (20)

1. A pharmaceutical composition suitable for oral delivery, comprising: At least one compound classified as BCSIII, wherein the at least one compound does not contain peptide bonds in the molecular structure of the compound; At least one absorption enhancer, wherein the at least one absorption enhancer comprises lauroyl carnitine; and The coated citric acid particles, wherein if the pharmaceutical composition is added to ten milliliters of a 0.1 M sodium bicarbonate aqueous solution, the amount of citric acid present in the pharmaceutical composition is sufficient to lower the pH of the solution to no higher than 5.5. 2. The pharmaceutical composition according to claim 1, wherein the pharmaceutical composition is a solid dosage form pharmaceutical composition. 3. The pharmaceutical composition according to claim 2, wherein the pharmaceutical composition is a multilayer solid dosage form pharmaceutical composition. 4. The pharmaceutical composition according to claim 1 or 2, wherein the at least one absorption enhancer comprises a surfactant. 5. The pharmaceutical composition according to claim 4, wherein the surfactant is an acid-soluble bile acid. 6. The pharmaceutical composition according to claim 1, further comprising an acid-resistant protective carrier. 7. The pharmaceutical composition according to claim 1 or 2, wherein the at least one compound is an antibiotic or an antiviral compound. 8. The pharmaceutical composition according to claim 1 or 2, wherein the at least one compound is selected from tigecycline, zanamivir, kanamycin, tobramycin, and fenofibrate. 9. The pharmaceutical composition according to claim 1, wherein the at least one compound, the at least one absorption enhancer, and the coated citric acid particles are mixed. 10. The pharmaceutical composition of claim 9, wherein the pharmaceutical composition further comprises: Enteric coating; and A water-soluble barrier is located between the enteric coating and the mixture of the at least one compound, the at least one absorption enhancer, and the coated citric acid particles, thereby separating the mixture from the enteric coating. 11. The pharmaceutical composition of claim 9, wherein the citric acid particles are coated with a water-soluble coating that separates the organic acid from the compound. 12. The pharmaceutical composition of claim 1, wherein oral administration results in a synergistic increase in the systemic bioavailability of the compound compared to the systemic bioavailability obtained by administering a pharmaceutical composition containing an equal amount of the compound but without the absorption enhancer and the citric acid. 13. Use of a pharmaceutical composition in the preparation of a medicament for enhancing the bioavailability of at least one compound classified as BCSIII for a therapeutically effective amount in a subject in need of such enhancement, said pharmaceutical composition comprising: At least one compound classified as BCSIII, wherein the at least one compound does not contain peptide bonds in the molecular structure of the compound; At least one absorption enhancer, wherein the at least one absorption enhancer comprises lauroyl carnitine; and The coated citric acid particles, among which If the pharmaceutical composition is added to 10 mL of 0.1 M sodium bicarbonate aqueous solution, the presence of citric acid in the pharmaceutical composition is sufficient to lower the pH of the solution to no higher than 5.5. 14. Use of a pharmaceutical composition in the preparation of a medicament for treating bacterial or viral infections in a subject with such need, said pharmaceutical composition comprising: At least one compound classified as BCSIII, wherein the at least one compound does not contain peptide bonds in the molecular structure of the compound; At least one absorption enhancer, wherein the at least one absorption enhancer comprises lauroyl carnitine; and The coated citric acid particles, among which If the pharmaceutical composition is added to 10 mL of 0.1 M sodium bicarbonate aqueous solution, the presence of citric acid in the pharmaceutical composition is sufficient to lower the pH of the solution to no higher than 5.5. 15. The use according to claim 13 or 14, wherein the at least one compound, the at least one absorption enhancer, and the coated citric acid particles are mixed. 16. The use according to claim 15, wherein the pharmaceutical composition further comprises: Enteric coating; and A water-soluble barrier is located between the enteric coating and the mixture of the at least one compound, the at least one absorption enhancer, and the coated citric acid particles, thereby separating the mixture from the enteric coating. 17. The use according to claim 15, wherein the citric acid particles are coated with a water-soluble coating that separates the citric acid from the at least one compound. 18. The use according to claim 13 or 14, wherein oral administration results in a synergistic increase in the systemic bioavailability of the compound compared to the systemic bioavailability obtained by administering a pharmaceutical composition containing an equal amount of the compound but without the absorption enhancer and the citric acid. 19. The pharmaceutical composition according to claim 1, wherein the at least one compound is a small molecule having a molecular weight of less than 2000 Daltons. 20. The pharmaceutical composition according to claim 1, wherein the at least one compound is a small molecule having a molecular weight of 50 to 500 Daltons.