HK1189518B - Hyaluronic acid-based gels including anesthetic agents - Google Patents

Description

Hyaluronic acid-based gels including anesthetic agents

The present application is a divisional application of an invention patent application having an application date of 2009, 3/2, application No. 200980139162.0, entitled "hyaluronic acid-based gel containing anesthetic agent".

Cross Reference to Related Applications

This application claims priority to U.S. provisional patent application No. 61/085,956 filed on 8/4/2008, U.S. provisional patent application No. 61/087,934 filed on 11/8/2008, U.S. provisional patent application No. 61/096,278 filed on 11/9/2008, U.S. non-provisional application No. 12/393,768 filed on 26/2/2009, and U.S. non-provisional application No. 12/393,884 filed on 26/2/2009, the entire disclosures of all of which are incorporated herein by reference.

Technical Field

The present invention relates generally to injectable soft tissue fillers and more particularly to hyaluronic acid-based skin and subcutaneous fillers including anesthetics.

Background

It is generally believed that as people age, the face begins to exhibit the effects of gravity, sun exposure, and long-term facial muscle movements (e.g., smiling, frowning, chewing, and squinting). Underlying tissue that keeps the skin looking young begins to deteriorate, often resulting in smiling lines, microsmiling lines, "crow's feet," and facial wrinkles that are commonly referred to as "aging effects.

In order to treat or correct the effects of aging, soft tissue fillers have been developed to help fill in facial lines and depressions, and to repair the reduction in tissue volume associated with fat loss. Whereby the soft tissue filler temporarily restores a smoother, younger appearance.

Ideally, soft tissue fillers are long-lasting, soft, smooth, and natural-looking when implanted in or under the skin. In addition, soft tissue fillers are easily implanted into a patient with a small gauge needle and require less compressive force to inject. The ideal filler should also not cause adverse side effects and should be injectable with little or no discomfort to the patient.

Collagen-based soft tissue fillers were developed over 20 years ago, and for some time bovine collagen-based fillers were the only skin fillers approved by the U.S. Food and Drug Administration (FDA). Since these dermal fillers are bovine based, one major drawback is that patients may develop allergies. It is believed that approximately 3-5% of human subjects exhibit severe allergic reactions to bovine collagen and therefore careful testing is required before using these fillers in any particular person. In addition to allergic reactions, collagen-based fillers degrade rapidly after injection and require frequent handling to maintain a smoother, younger appearance.

In month 2 of 2003, collagen filler compositions derived from humans were FDA approved. The advantage of these collagens is the significantly reduced risk of allergy. However, despite the reduced incidence of allergic reactions, collagen fillers derived from humans still face the problem of rapid degradation of the injected product.

Research directed to fillers that do not cause allergy and maintain a smoother, younger appearance HAs led to the development of Hyaluronic Acid (HA) -based products. The first HA-based filler was FDA approved 12 months in 2003. The development of other HA-based fillers was followed.

HA, also known as hyaluronan, is a natural water-soluble polysaccharide, specifically a glycosaminoglycan, a major component of the extracellular matrix and is widely distributed in animal tissues. HA HAs excellent biocompatibility and does not cause allergic reactions when implanted in patients. In addition, HA is able to bind large amounts of water, which makes it a good soft tissue bulking agent (volumizer).

It HAs proven difficult to develop HA-based fillers that exhibit desirable properties in vivo and desirable surgical usability. For example, HA-based fillers that exhibit desirable stability in vivo may be so viscous that injection through a small gauge needle is very difficult. In contrast, HA-based fillers that are relatively easy to inject through a small gauge needle often have relatively poor stability in vivo.

One way to overcome this difficulty is to use crosslinked HA-based fillers. Crosslinked HA is formed by reacting free HA with a crosslinking agent under suitable reaction conditions. Methods of preparing HA-based soft tissue fillers comprising crosslinked HA and free HA are known.

It HAs been proposed to add certain therapeutic agents, such as anesthetics (e.g., Lidocaine (Lidocaine)) to injectable HA-based compositions. Unfortunately, HA-based injectable compositions incorporating lidocaine during preparation are prone to partial or almost complete degradation prior to injection, particularly during high temperature sterilization procedures and/or when stored for significant periods of time.

One object of the HA-based soft filler compositions and methods of making and using them described herein is to provide soft tissue fillers that do not cause an allergic reaction in a patient, are biocompatible, are stable and useful in vivo, and include one or more local anesthetics.

Disclosure of Invention

The present specification relates to soft tissue fillers, such as dermal and subdermal fillers, based on Hyaluronic Acid (HA) and pharmaceutically acceptable salts of HA, such as sodium hyaluronate (NaHA). The HA-based compositions described herein include a therapeutically effective amount of at least one anesthetic agent. In one embodiment, for example, the anesthetic is lidocaine. The HA-based compositions of the invention comprising at least one anesthetic have an enhanced stability when subjected to sterilization techniques such as autoclaving and/or when stored for extended periods at room temperature, as compared to conventional HA-based compositions comprising, for example, lidocaine. Also provided are methods of making such HA-based compositions and products made by such methods.

Described herein are soft tissue filler compositions, the compositions generally comprising: a hyaluronic acid component cross-linked by a cross-linking agent selected from the group consisting of: 1, 4-butanediol diglycidyl ether (BDDE), 1,4-bis (2, 3-epoxypropoxy) butane, 1, 4-diglycidyloxybutane (1, 4-diglycidyloxybutane), 1, 2-bis (2, 3-epoxypropoxy) ethylene and 1- (2, 3-epoxypropyl) -2, 3-epoxycyclohexane and 1, 4-butanediol diglycidyl ether.

In yet another embodiment, the at least one anesthetic is lidocaine. In another embodiment, the amount of anesthetic is present at a concentration of about 0.1% to about 5.0% by weight of the composition. In another embodiment, the anesthetic is present at a concentration of about 0.2% to about 1.0% by weight of the composition. In one embodiment, the anesthetic is lidocaine and is present at about 0.3% by weight of the composition.

In yet another embodiment, the soft tissue filler composition has a squeezing force of about 10N to about 13N at a rate of, for example, about 12.5 mm/min. In another embodiment, the viscosity of the composition is from about 5Pa s to about 450Pa s, when measured, for example, at about 5 Hz.

In one embodiment, the HA component is a gel, e.g., a cohesive hydrated gel. In one embodiment, the HA component is a crosslinked HA gel having no more than about 1% to about 10% free HA. For purposes of this disclosure, free HA includes indeed free HA in all soluble forms in water as well as lightly crosslinked HA chains and fragments.

In other embodiments, the HA component comprises more than about 10% (e.g., more than about 15%, such as up to or more than about 20%) free HA.

In yet another embodiment, the HA component is a gel of cross-linked HA particles contained in a relatively liquid medium of free HA. In some embodiments, the HA component HAs an average particle size of greater than about 200 μm, for example, greater than about 250 μm.

Also described herein is a soft tissue filler composition comprising: an HA component crosslinked by 1, 4-butanediol diglycidyl ether (BDDE) and an anesthetic component at a concentration of about 0.1% to about 5.0% by weight of the soft tissue filler composition, wherein the HA component HAs a degree of crosslinking of less than about 5%, such as about 2%, wherein the anesthetic is lidocaine.

Also described herein is a method of making a soft tissue filler composition, the method comprising the steps of: providing an HA component crosslinked by at least one crosslinking agent selected from the group consisting of 1, 4-butanediol diglycidyl ether (BDDE), 1,4-bis (2, 3-epoxypropoxy) butane, 1, 4-diglycidoxybutane, 1, 2-bis (2, 3-epoxypropoxy) ethylene, and 1- (2, 3-epoxypropyl) -2, 3-epoxycyclohexane, and 1, 4-butanediol diglycidyl ether or combinations thereof; adjusting the pH of the HA component to an adjusted pH above about 7.2; and adding a solution containing at least one anesthetic to the HA component having the adjusted pH to obtain an HA-based filler composition.

In another embodiment, the composition is sterilized, such as by autoclaving, to form a sterilized composition, and wherein the sterilized composition is stable at room temperature for at least about several months — for example, at least 9 months, at least about 12 months, such as at least about 36 months, or longer.

In yet another embodiment, the adjusted pH is above about 7.5. In another embodiment, said method further comprises the step of homogenizing said HA component during or after said step of adding said solution containing said at least one anesthetic. In another embodiment, the homogenizing step comprises mixing the composition with controlled shear.

In another embodiment, the step of providing the HA component comprises: providing a dried free NaHA material, and hydrating the dried free NaHA material in an alkaline solution to obtain a free alkaline NaHA gel. In yet another embodiment, the pH of the free alkaline NaHA material is above about 8.0. In yet another embodiment, the pH is above about 10.

In another embodiment, the HA component comprises greater than about 20% free HA, and the degree of crosslinking of the crosslinked portion of the HA component is less than about 6% or less than about 5%.

In yet another embodiment, the soft tissue filler composition HAs a particulate nature in that it comprises crosslinked HA particles dispersed in a liquid soluble HA medium. In some embodiments, the average size of such particles is at least about 200 μm, and in other embodiments, the average size of such particles is at least about 250 μm.

Also described herein is a soft tissue filler composition comprising: a Hyaluronic Acid (HA) component crosslinked by 1, 4-butanediol diglycidyl ether (BDDE) and an anesthetic component at a concentration of about 0.1% to about 5.0% by weight of the soft tissue filler composition, wherein the HA component HAs a degree of crosslinking of less than about 5%, wherein the anesthetic is lidocaine.

In a particular embodiment of the present invention, a method of making a soft tissue filler composition is also described, the method comprising the steps of: providing a dried free NaHA material and hydrating the dried free NaHA material in an alkaline solution to obtain a free alkaline NaHA gel; crosslinking the free NaHA gel with BDDE to form a crosslinked basic HA composition having a degree of crosslinking of less than about 5% and a pH of greater than about 7.2; adding a solution containing lidocaine HCl to the HA component having the adjusted pH to obtain the HA-based filler composition; homogenizing the HA-based filler composition, thereby forming a homogenized HA-based filler composition; and sterilizing the homogenized HA-based filler composition, thereby forming a sterilized HA-based filler composition, wherein the soft tissue filler composition HAs a particle size of greater than about 200 μm, for example, a particle size of greater than about 250 μm.

Drawings

FIG. 1 illustrates the viscosity versus shear frequency for sample 1 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbon but without pH adjustment during formation.

Figure 2 illustrates the viscosity versus shear frequency for sample 2 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbone during formation but without pH adjustment.

Figure 3 illustrates the viscosity versus shear frequency for sample 3 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbone during formation but without pH adjustment.

Fig. 4 illustrates the viscosity versus shear frequency for sample 4 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbone during formation but without pH adjustment.

Fig. 5 illustrates the viscosity versus shear frequency for sample 5 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbon during formation but without pH adjustment.

Fig. 6 illustrates the relative viscous/elastic properties versus shear frequency for sample 5 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbone but without pH adjustment during formation.

Fig. 7 illustrates the viscosity versus shear frequency for sample 6 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbone during formation but without pH adjustment.

Fig. 8 graphically illustrates the relative viscous/elastic properties versus shear frequency for sample 6 prepared without lidocaine during formation, with lidocaine and pH adjustment during formation, and with polycarbone but without pH adjustment during formation.

Figure 9 illustrates the lidocaine concentration versus time in the gel from sample 5 of example 4, prepared by the method of test 2.

Definition of

Certain terms used in the present specification are intended to have the definitions detailed below. Where a definition of a term deviates from the usual meaning of that term, applicant intends to use the definition provided below, unless specifically indicated.

An autoclave-stable or autoclave-stable product or composition is used herein to describe a product or composition that is resistant to degradation such that the product or composition retains at least one, and preferably all, of the following aspects after effective autoclaving: appearance of clarity, pH, extrusion force and/or rheological characteristics, Hyaluronic Acid (HA) concentration, sterility, osmolarity, and lidocaine concentration.

Centrifugation, as used herein, refers to the process of uniformly dispersing a material of greater and lesser density using centrifugal force. Centrifugation is typically used to separate the liquid phase from the solid or gel phase. The basic phase separated by centrifugation should be at least a macroscopic separator, e.g. a liquid phase and a solid phase that clearly separate when viewed with the naked eye.

Described herein as having at least about one million daltons (mw ≧ 10) using high molecular weight HA⁶Da or 1 MDa) to about 4.0 MDa. For example, the high molecular weight HA in the compositions of the present invention may have a molecular weight of about 2.0 MDa. In another example, the high molecular weight HA may have a molecular weight of about 2.8 MDa.

Low molecular weight HA is used herein to describe HA materials having a molecular weight of less than about 1.0 MDa. The low molecular weight HA may have a molecular weight of about 200,000Da (0.2 MDa) to less than about 1.0MDa, for example about 300,000Da (0.3 MDa) to about 750,000Da (0.75 MDa).

The degree of crosslinking, as used herein, refers to the intermolecular linkage that links the individual HA polymer molecules or monomer chains into a permanent structure or soft tissue filler composition as disclosed herein. Further, for purposes of this disclosure, the degree of crosslinking is also defined as the weight percent (percent weight ratio) of crosslinker to HA monomer units in the crosslinked portion of the HA-based composition. The degree of crosslinking is measured by the weight ratio of the HA monomer to the crosslinking agent (HA monomer: crosslinking agent).

Free HA, as used herein, refers to individual HA polymer molecules that are not crosslinked to, or are very lightly crosslinked (very low degree of crosslinking), the highly crosslinked (higher degree of crosslinking) macromolecular structure comprising the soft tissue filler composition. Free HA generally remains water soluble. Free HA can alternatively be defined as the "uncrosslinked" or lightly crosslinked component of the macromolecular structure comprising the soft tissue filler composition disclosed herein.

Cohesion, as used herein, is the ability of the HA-based composition to retain its shape and resist deformation. Cohesiveness is affected by factors such as the molecular weight ratio of the initial free HA, the degree of crosslinking, the amount of free HA remaining after crosslinking, and the pH of the HA-based composition. Furthermore, cohesive HA-based compositions resist phase separation when tested according to the method disclosed in example 1 herein.

Detailed Description

The present disclosure relates generally to soft tissue fillers, such as dermal and subdermal fillers, based on Hyaluronic Acid (HA) and pharmaceutically acceptable salts of HA, such as sodium hyaluronate (NaHA). In one aspect, the HA-based compositions described herein include a therapeutically effective amount of at least one anesthetic, such as lidocaine. The HA-based compositions of the invention comprising at least one anesthetic have enhanced stability when subjected to high temperature and pressure treatments, such as those experienced during heat and/or pressure sterilization techniques, such as autoclaving, and/or when stored for extended periods of time, such as at room temperature, as compared to conventional HA-based compositions containing, for example, lidocaine.

The stable compositions retain at least one or all of the following aspects after effective autoclaving and/or long storage times: clear appearance, pH, extrusion force and/or rheological characteristics available to the patient, HA concentration, sterility, osmolarity, and lidocaine concentration. Methods or processes for preparing such HA-based compositions and products prepared by these methods or processes are also provided.

As used herein, Hyaluronic Acid (HA) may refer to any hyaluronate salt thereof, and includes, but is not limited to, sodium hyaluronate (NaHA), potassium hyaluronate, magnesium hyaluronate, calcium hyaluronate, and combinations thereof.

Generally, the concentration of HA in the compositions described herein is preferably at least 10mg/mL and up to about 40 mg/mL. For example, in some such compositions the concentration of HA is from about 20mg/mL to about 30 mg/mL. Further, for example, in some embodiments, the HA concentration of the composition is about 22mg/mL, about 24mg/mL, about 26mg/mL, or about 28 mg/mL.

Further, the concentration of the one or more anesthetic agents is an amount effective to reduce pain experienced upon injection of the composition. The at least one local anesthetic may be selected from the group consisting of ambucaine (ambucaine), amorolone (amonolone), amethocaine (amoylcaine), oxybuprocaine (benoxinate), benzocaine (benzocaine), bepotocaine (betaxycaine), phensalate (biphenamine), bupivacaine (bupivacaine), butacaine (butacaine), butamben (butamben), mecocaine (butanaceine), butambene (butethiamine), butamben (butroxycaine), carticaine (carticaine), chloroprocaine (chlorophromaine), hexylbenzoyl exocaine (cocaine), cocaine (cocaine), cyclomethiocaine (cyclomethiothecin), dibucaine (dibucaine), dimethylisoquin (dimethylisoquizaine), dimethylocarpine (dimethylocarpine), dicaine (dicaine), dicaine (betamethasone), procaine (tetracaine), tetracaine (tetracaine), dimethylisocarboxide), dimethylpiclorane (tetracaine), dimethylpiclorane, betamethacin), tetracaine (tetracaine), tetracaine (tetracaine, formocaine, hecocaine (hexylcaine), oxybutynin (hydxytetracaine), isobutyl p-aminobenzoate (isobutryl p-aminobenzoxazole), leukacaine mesylate (leucocaine mesylate), levosaldol (levoxadrol), lidocaine (lidocaine), mepivacaine (mepivacaine), mepivacaine (mepropycaine), mebucaine (metabisucaine), chloromethane, etidocaine (myrtacaine), naepaine (napaine), otacaine (ocaine), oxocaine (ortocaine), oxicaine (oxytocaine), hydroxyethylcaine (oxethazine), paraethoxycaine (parecoxycaine), phenacaine (phenacaine), phenol, perucaine (piperococaine), lidocaine (prilocaine), polyethylene glycol monothiodocaine ether (ether), procaine (proparacaine), procaine (propipocaine), procaine (proparacaine), procaine (proparacaine), proparacaine (proparacaine), proparacai, Saligenin, tetracaine (tetracaine), tolicaine (tolycaine), trimecaine (trimecaine), zolamide (zolamide), and salts thereof. In one embodiment, the at least one anesthetic is lidocaine, for example in the form of lidocaine HCl. The lidocaine concentration of the compositions described herein can be from about 0.1% to about 5% by weight of the composition, for example from about 0.2% to about 1.0% by weight of the composition. In one embodiment, the composition has a lidocaine concentration of about 0.3% of the composition. The concentration of lidocaine in the compositions described herein can be a therapeutically effective amount, meaning that the concentration is sufficient to provide therapeutic benefit without harm to the patient.

In one aspect of the present invention, there is provided a method of preparing an HA-based composition comprising an effective amount of lidocaine, wherein the method comprises: providing a precursor composition comprising a cross-linked cohesive HA-based gel, adding a solution comprising lidocaine (e.g. in the form of lidocaine HCl) thereto, and homogenizing the resulting mixture to obtain an at least partially cross-linked cohesive HA-based composition comprising lidocaine, said composition being stable to autoclaving. The crosslinked, cohesive HA-based gel comprises no more than about 1% to about 10% by volume free HA material, for example, no more than about 5% free HA material.

In some embodiments of the invention, the HA component of the compositions of the invention, sometimes referred to hereinafter as the "precursor composition," is a hydrated, cohesive gel. Cohesive gels are more able to retain their shape and resist deformation, e.g., after shear or other pressure treatment, than non-cohesive gels. The inventors have found that such cohesive gels are less likely to degrade significantly or become unstable over time or when subjected to an external stimulus such as sterilization, as compared to non-cohesive gels.

Without wishing to be bound by any particular theory of operability, it is believed that, in some embodiments of the present invention, the cohesiveness of the precursor composition serves to substantially or completely prevent or retard the decomposition or degradation of crosslinked HA in the lidocaine-added composition.

It is believed that such degradation may occur primarily because many, and possibly most, crosslinked HA-based gels are prepared according to conventional methods in a manner that results in gels that are not sufficiently cohesive to prevent such degradation when lidocaine is added. It HAs now been found that the addition of lidocaine to a sufficiently cohesive cross-linked HA-based composition does not cause significant or significant degradation of the composition, and that the composition retains its integrity in terms of rheology, viscosity, appearance and other characteristics, even when stored at, for example, room temperature for an extended period of time, for example, at least about 6 months, about 9 months, about 12 months, or about 36 months or more, and even after being subjected to a sterilization operation, such as an autoclaving process.

It HAs been surprisingly found that a cross-linked HA-based composition formulation comprising lidocaine can be prepared in a manner to produce a sterile-stable, injectable HA/lidocaine composition.

Also described herein is a method of preparing a stable HA-based composition containing an effective amount of lidocaine by: preparing a precursor composition, e.g., a cross-linked cohesive HA-based gel, adding lidocaine hydrochloride (lidocaine hydrochloride) to the gel to form an HA/lidocaine gel mixture, and homogenizing the resulting mixture to obtain a cross-linked HA-based composition that is stable to autoclaving.

In certain embodiments, the precursor composition is a hydrated, cohesive HA-based gel. Such "cohesive" gels generally include no more than about 1% to about 10% by volume of free HA in soluble liquid form. Such cohesive gels are considered by some in the industry as single phase or substantially single phase compositions because less than about 1% to about 10% of the composition contains free HA.

In further embodiments, the precursor composition is a hydrated, relatively non-cohesive HA-based gel. Such "non-cohesive" gels typically contain more than 10% (e.g., more than about 15%, e.g., more than 20% or more) free HA.

In certain embodiments, the precursor composition can comprise a first component consisting of relatively highly crosslinked HA that is substantially a solid phase and a second component comprising free or relatively less crosslinked HA that is substantially a liquid phase in which the relatively highly crosslinked HA is dispersed.

In some embodiments, the compositions of the present invention have some degree of particulate character and comprise relatively highly crosslinked HA microparticles dispersed in a medium of free HA. In some embodiments, the average size of the crosslinked HA particles is at least about 200 μm or at least about 250 μm. The cohesiveness of such particulate compositions is generally inferior to other similar compositions (with no discernible particles, or with particles having an average size of less than 200 μm).

For example, in some embodiments, the precursor composition may be prepared by extruding a mass of relatively highly crosslinked HA-based gel through a screen or mesh to produce relatively highly crosslinked HA particles of approximately the same size and shape. These particles are then mixed with a carrier material, such as an amount of free HA, to produce a gel.

In other embodiments, there is provided a method of preparing an HA-based composition comprising an effective amount of lidocaine, wherein the method comprises: providing a precursor composition comprising an HA-based gel that is substantially neutral in pH, at least partially crosslinked, and adjusting the pH of the gel to a pH in excess of about 7.2, such as from about 7.5 to about 8.0. The method further comprises the step of combining a solution containing lidocaine (e.g. in the form of lidocaine HCl) with the weakly basic gel after the pH HAs been so adjusted, and obtaining a composition comprising an HA-based composition comprising lidocaine that is stable to autoclaving.

As described elsewhere herein, another method of preparing a stable HA-based combination comprising an effective amount of lidocaine generally comprises the steps of: providing a purified NaHA material, e.g., in the form of fibers; hydrating the material; and crosslinking the hydrated material with a suitable crosslinking agent to form a crosslinked HA-based gel. The method further comprises the steps of: the gel is neutralized and swollen and a solution comprising lidocaine (preferably an acid salt of lidocaine hydrochloride) is added to the gel to form an HA/lidocaine gel. In addition, the method further comprises homogenizing the HA/lidocaine gel and filling the homogenized HA/lidocaine gel into, for example, a syringe for dispensing. The syringe is then sterilized by autoclaving at an effective temperature and pressure. According to the present description, the packaged and sterilized cohesive NaHA/lidocaine gels exhibit enhanced stability compared to HA-based compositions containing lidocaine prepared using conventional methods.

Products and compositions of the present invention are considered sterile by exposing them to temperatures of at least about 120 ℃ to about 130 ℃ and/or pressures of at least about 12 pounds Per Square Inch (PSI) to about 20PSI for a period of time of at least about 1 minute to about 15 minutes during autoclaving.

The products and compositions of the present invention remain stable when stored for extended periods at room temperature. The compositions of the present invention preferably remain stable at a temperature of at least about 25 ℃ for a period of at least about 2 months, or at least about 6 months, or at least about 9 months, or at least about 12 months, or at least about 36 months. In a particular embodiment, the composition remains stable for a period of at least 2 months at temperatures up to about 45 ℃.

In one embodiment, the preparation method comprises a starting step of providing the HA raw material in the form of dry HA fibers or powder. The HA starting material may be HA, its salts and/or mixtures thereof. In a preferred embodiment, the HA material comprises fibers or powder of NaHA, and even more preferably of bacterial origin. In some aspects of the present description, the HA material may be of animal origin. The HA material may be a combination of a starting material comprising HA and at least one other polysaccharide, such as a glycosaminoglycan (GAG).

In some embodiments, the HA material in the composition comprises or consists essentially of high molecular weight HA. That is, almost 100% of the HA material in the composition of the invention may be high molecular weight HA as defined above. In other embodiments, the HA material in the composition comprises a combination of relatively high molecular weight HA and relatively low molecular weight HA as defined above.

The HA material of the composition may comprise from about 5% to about 95% high molecular weight HA, with the remainder comprising low molecular weight HA material. In one embodiment of the invention, the ratio of high molecular weight HA to low molecular weight HA is at least about 2 (w/w ≧ 2), and preferably more than 2, wherein the molecular weight of the high molecular weight HA is more than 1.0 MDa.

Those skilled in the art will appreciate that the selection of high and low molecular weight HA materials and their relative percentages or ratios will depend on the desired characteristics, such as extrusion force, elastic modulus (elastic modulus), viscous modulus (viscous modulus) and phase angle expressed as the ratio of viscous modulus to elastic modulus, cohesion, etc., of the HA-based end product. For additional information that may aid in understanding this and other aspects of the present disclosure, see U.S. patent application No.2006/0194758 to Lebreton, the entire disclosure of which is incorporated herein by reference.

In accordance with the present specification, the HA-based gel may be prepared by first washing and purifying a dried HA material or HA raw material having the desired high/low molecular weight ratio. These steps generally involve hydrating dried HA fiber or powder having the desired high/low molecular weight ratio, for example, with pure water, and filtering the material to remove large foreign matter and/or other impurities. The filtered, hydrated material is then dried and purified. The high and low molecular weight HA's may be washed and purified separately, or may be mixed together, for example, in the desired ratio, and subsequently crosslinked.

In one aspect of the disclosure, pure, dried NaHA fibers are hydrated in an alkaline solution to produce a free NaHA alkaline gel. The NaHA may be hydrated in this step using any suitable alkaline solution, such as, but not limited to, solutions containing sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium bicarbonate (NaHCO)₃) And lithium hydroxide (LiOH). In another embodiment, a suitable alkaline solution is an aqueous solution containing NaOH. The pH of the resulting basic gel will exceed 7.5. The pH of the resulting basic gel may exceed 9, or exceed 10, or exceed 12, or exceed 13.

The next step in the preparation process involves the step of cross-linking the hydrated alkaline NaHA gel with a suitable cross-linking agent. The cross-linking agent may be any agent known to be suitable for cross-linking polysaccharides and their derivatives via their hydroxyl groups. Suitable crosslinking agents include, but are not limited to, 1, 4-butanediol diglycidyl ether (or 1,4-bis (2, 3-epoxypropoxy) butane or 1, 4-diglycidyloxybutane, all of which are commonly referred to as BDDE), 1, 2-bis (2, 3-epoxypropoxy) ethylene, and 1- (2, 3-epoxypropyl) -2, 3-epoxycyclohexane. The scope of the present disclosure does not preclude the use of more than one crosslinker or the use of different crosslinkers. In one aspect of the present disclosure, the HA gels described herein are crosslinked with BDDE.

The crosslinking step may be performed using any method known to those skilled in the art. The person skilled in the art understands how to optimize the crosslinking conditions according to the properties of HA and how to proceed to an optimal extent.

For purposes of the present disclosure, the degree of crosslinking is defined as the weight percent of crosslinker and HA monomer units in the crosslinking portion of the HA-based composition. The degree of crosslinking is measured by the weight ratio of the HA monomer to the crosslinking agent (HA monomer: crosslinking agent).

The degree of crosslinking in the HA component of the composition of the present invention is at least about 2% and at most about 20%.

In other embodiments, the degree of crosslinking is greater than 5%, for example, from about 6% to about 8%.

In some embodiments, the degree of crosslinking is from about 4% to about 12%. In some embodiments, the degree of crosslinking is less than about 6%, for example less than about 5%.

In some embodiments, the HA component is capable of absorbing at least about one time its weight in water. When neutralized and swollen, the cross-linked HA component and the cross-linked HA component absorb water in a weight ratio of about 1: 1. The obtained hydrated HA-based gel HAs the characteristic of high cohesiveness.

The HA-based gels of some embodiments of the present invention may be sufficiently cohesive that the gels do not suffer significant phase separation after centrifugation at 2000rd/min for 5 minutes. In another embodiment, the gel has the property of being able to absorb at least 1 times its weight of water and is sufficiently cohesive that the gel retains its integrity when swollen with water, e.g., when subjected to centrifugation, at a weight ratio of about 1:1 gel/water.

The hydrated crosslinked HA gel can be swollen to give the desired cohesiveness. This step can be accomplished by neutralizing the crosslinked hydrated HA gel, for example, by adding an aqueous solution containing an acid such as HCl. The gel was then swollen in a Phosphate Buffered Saline (PBS) solution and at low temperature for a sufficient time.

In one embodiment, the resulting swollen gel has a high cohesion and no distinct (visual distinting) particles, e.g., no distinct particles when viewed with the naked eye. In one embodiment, the gel has no distinct particles at a magnification of less than 35 x.

The substantially single phase cohesive gel is now purified by conventional means, such as dialysis or alcohol precipitation, to recover the crosslinked material, stabilize the pH of the material, and remove any unreacted crosslinking agent. Additional water or weakly alkaline aqueous solution may be added to bring the NaHA concentration to the desired concentration.

The pH of the purified, substantially pH neutral, crosslinked HA gel is preferably adjusted to make the gel weakly basic such that the pH of the gel exceeds about 7.2, e.g., about 7.5 to about 8.0. This step can be accomplished by any suitable method, for example by adding a suitable amount of dilute NaOH, KOH, NaHCO to the gel₃Or LiOH or any other basic molecule, solution and/or buffer composition known to those skilled in the art.

An effective amount of lidocaine, such as lidocaine HCl, is then added to the purified cohesive NaHA gel. For example, in some embodiments, the lidocaine HCl is provided in the form of a powder that is dissolved with water for injection (WFI). The gel is kept neutral with a buffer or by adjustment with dilute NaOH so that the final HA/lidocaine composition HAs the desired substantially neutral pH. The final HA-based filler composition comprising lidocaine HAs a lidocaine concentration of at least about 0.1% to about 5%, e.g., about 2w/w%, or in another embodiment about 0.3% of the composition.

After or, alternatively, during the addition of lidocaine HCl, the HA/lidocaine gel or composition is homogenized to produce a highly uniform cohesive HA/lidocaine gel having the desired consistency and stability. The homogenization step may include mixing, stirring, or beating the gel with controlled shear forces to obtain a substantially homogeneous mixture.

The HA/lidocaine compositions described herein exhibit a viscosity that depends on the nature of the composition and the presence of at least one anesthetic. The HA/lidocaine composition can have a viscosity of about 50Pa s to about 450Pa s. In other embodiments, the viscosity may be from about 50Pa s to about 300Pa s, from about 100Pa s to about 400Pa s, or from about 250Pa s to about 400Pa s, or from about 50Pa s to about 250Pa s.

After homogenization, the HA/lidocaine composition was introduced into a syringe and sterilized. Syringes useful in the present description include any syringe known in the art capable of delivering viscous skin filler compositions. The internal volume of the syringe is generally from about 0.4mL to about 3mL, more preferably from about 0.5mL to about 1.5mL or from about 0.8mL to about 2.5 mL. This internal volume is related to the inner diameter of the syringe, which has an important role in the squeezing force required to inject the highly viscous dermal filler composition. The inner diameter is generally from about 4mm to about 9mm, more preferably from about 4.5mm to about 6.5mm or from about 4.5mm to about 8.8 mm. Furthermore, the squeezing force required to deliver the HA/lidocaine composition from the syringe depends on the gauge of the needle. The gauge of the needle used generally includes a gauge of about 18G to about 40G, more preferably a gauge of about 25G to about 33G or a gauge of about 16G to about 25G. Those skilled in the art can determine the correct syringe size and needle gauge needed to meet the specific squeeze force requirements.

The compressive force exhibited by the HA/lidocaine compositions described herein using the above-described needle sizes is that at an injection speed that is comfortable for the patient. Comfort for the patient is used to define an injection rate that does not cause harm or cause excessive pain to the patient when injected into soft tissue. One skilled in the art will appreciate that comfort as used herein includes not only patient comfort, but also the comfort and ability of a physician or medical technician to inject the HA/lidocaine composition. While certain extrusion forces can be achieved with the HA/lidocaine compositions of the present description, those skilled in the art understand that high extrusion forces can result in lack of control during injection, and that such lack of control can cause additional pain to the patient. The extrusion force of the HA/lidocaine compositions of the invention can be from about 8N to about 15N, or more preferably from about 10N to about 13N, or from about 11N to about 12N at an extrusion rate of, for example, about 12.5 mm/min.

Sterilization, as used herein, includes any method known in the art that is effective in killing or eliminating infectious agents and preferably does not substantially alter the degradation of the HA/lidocaine composition.

One preferred method of sterilizing filled syringes is by autoclaving. Autoclaving can be accomplished by applying a mixture of heat, pressure and water vapor to the specimen to be sterilized. Many different sterilization temperatures, pressures and cycle times can be used for this step. For example, the filled syringe may be sterilized at a temperature of at least about 120 ℃ to about 130 ℃ or more. Moisture may or may not be used. The pressure applied is dependent on the temperature used during sterilization in some embodiments. The sterilization cycle may be at least about 1 minute to about 20 minutes or more.

Another method of sterilization involves the use of gaseous substances known to kill or eliminate infectious agents. Preferably, ethylene oxide is used as the sterilizing gas and is known in the art to be useful for sterilizing medical devices and products.

Another method of sterilization involves the use of radiation sources known in the art to kill or eliminate infectious agents. A beam of radiation is directed at a syringe containing the HA/lidocaine solution and energy at this wavelength kills or eliminates unwanted infectious agents. Preferred useful energies include, but are not limited to, Ultraviolet (UV) light, gamma rays, visible light, microwaves, or any other wavelength or band that kills or eliminates unwanted infectious agents, preferably without substantially altering the degradation of the HA/lidocaine composition.

In another embodiment, a method of making a cohesive HA-based composition is also described, the method generally comprising the steps of: providing a cross-linked HA-based gel free of anesthetic (hereinafter, sometimes referred to as precursor gel), adjusting the pH of the precursor gel to obtain a gel having a pH of about 7.2 to 8.0, and adding a suitable amount of lidocaine or other anesthetic to the pH-adjusted gel to obtain a cohesive HA-based composition containing anesthetic. In one embodiment, the precursor gel is a substantially single phase, high cohesive gel comprising no more than about 1% to about 10% by volume free HA (e.g., no more than about 10% by volume free HA). In another embodiment, the precursor gel is a relatively low cohesive gel comprising at least 10% by volume to about 20% by volume or more free HA.

Example 1

Method for testing gel cohesion

For purposes of illustration only and not to be construed as limiting the invention in any way, the following tests may be conducted to demonstrate or quantify the cohesiveness of the HA-based gel composition.

First, 0.2g or 0.4g of the gel composition to be tested was placed in a glass syringe. Next, 0.2g or more of phosphate buffer was added to the syringe and the resulting mixture was thoroughly mixed for about 1 hour to obtain a uniform mixture. The homogeneous mixture was then centrifuged at 2000tr/min for 5 minutes to remove air bubbles and allow all particles to decant (decantation). The syringe was then held upright and a drop of eosin was applied to the surface of the gel through the syringe and 18G needle. After 10 minutes, the dye had slowly diffused through the gel.

After dilution, homogenization and decantation of the gel, the relatively low cohesive gel shows phase separation (a diluted, lower viscosity, particle-free upper phase and a lower phase consisting of decanted particles visible to the naked eye or under a microscope). Under the same conditions, the highly cohesive gel shows substantially no phase separation and the dye cannot diffuse into the cohesive formulation. On the other hand, relatively low cohesive gels show clear phase separation.

Example 2

Synthetic lidocaine-containing soft tissue filler

The NaHA fiber or powder is hydrated in an alkaline solution, such as an aqueous solution containing NaOH. The mixture was mixed at room temperature about 23 ℃ to form a substantially homogeneous basic HA gel.

The crosslinking agent BDDE was diluted in aqueous solution and added to the basic HA gel. The resulting mixture was homogenized for several minutes.

Alternatively, BDDE may be added directly to the HA fibers (dry state) at the beginning of the process, followed by hydration. The crosslinking reaction then starts relatively slowly at room temperature, ensuring better crosslinking uniformity and efficacy. Methods of crosslinking polymers in the dry state with multifunctional crosslinking agents such as BDDE are described, for example, in Piron et al, U.S. patent No.6,921,819, which is incorporated by reference herein in its entirety to the extent it is part of this specification.

The resulting crosslinked HA gel mixture was then heated at about 50 ℃ for about 2.5 hours. The material is now a highly cross-linked HA/BDDE gel (appearance = solid gel). The crosslinked gel is then neutralized with a suitable acidic solution. The neutralized HA gel is then swollen in phosphate buffer at low temperature (e.g., a temperature of about 5 ℃) to obtain a highly cohesive HA gel. In this particular example, the phosphate buffered saline solution comprises water for injection (WFI), disodium hydrogen phosphate and sodium dihydrogen phosphate. When neutralized and swollen, the cross-linked HA component and the cross-linked HA component absorb water in a weight ratio of about 1: 1.

The swollen cohesive HA gel was then mechanically stirred, filled into dialysis membranes and dialyzed against phosphate buffer. The HA gel was then filled into dialysis membranes and dialyzed with phosphate buffer for up to several days, and the dialysate was periodically changed to remove unreacted cross-linking agent, stabilize the pH to near neutral (pH = 7.2), and ensure proper osmolarity of the HA gel. The resulting cohesive HA gel HAs an osmolality of from about 200mOsmol to about 400mOsmol, most preferably about 300 mOsmol.

After dialysis, the resulting cohesive HA gel HAs a pH of substantially neutral, preferably about 7.2, and no distinct particles in the liquid medium when observed at a magnification of less than 35 x.

Lidocaine hydrochloride (lidocaine HCl) in powder form was first dissolved with WFI and filtered through a 0.2 μm filter. Dilute NaOH solution is added to the cohesive HA gel to achieve a slightly alkaline pH (e.g., a pH of about 7.5 to about 8). The lidocaine HCl solution is then added to the weakly basic gel to achieve the final desired concentration, e.g., a concentration of about 0.3% (w/w). The resulting HA/lidocaine mixture then had a pH of about 7, and the HA concentration was about 24 mg/mL. Mechanical mixing was carried out in a standard reactor equipped with appropriate stirring mechanisms to obtain the appropriate homogeneity. The resulting composition is cohesive.

If desired, a suitable amount of free HA gel may be added to the HA/lidocaine gel mixture, which HAs the benefit of increasing the kinetics of lidocaine delivery. For example, free HA fibers are swollen in phosphate buffer to give a homogeneous viscoelastic gel. This free HA gel is then added to the crosslinked HA/lidocaine gel (e.g., at about 5%, w/w). The resulting gel is then filled into sterile syringes and autoclaved at sufficient sterilization temperature and pressure for at least about 1 minute.

After autoclaving, the final HA/lidocaine product is packaged and distributed to the physician. The product prepared according to this process exhibits one or more stability characteristics as defined elsewhere herein. For example, the autoclaved HA/lidocaine product HAs acceptable viscosity, cohesiveness, and extrusion forces. The HA/lidocaine gel product was not found to degrade in product testing conducted after months of storage.

Example 3

Characteristics of soft tissue fillers

The properties of the HA/lidocaine compositions prepared according to the method described herein are shown in table 1 below. For example, the pressing force is usedMeasured by advanced materials testing System model 5564 (Instron, Norwood, MA), runSoftware version 2.11 (Instron, Norwood, MA). By bands running Empersor softwareVersa test Column (Versa test Column) and TERMO FISH HER for dynamometer AGF100N (Mecmesin Limited, West Sussex, United Kingdom)Rheometer RS600 (Thermo Fisher Scientific, inc. corp., Waltham, MA) collects additional rheological data.

TABLE 1

	HA/lidocaine compositions
		Appearance of the product	Homogeneous transparent gel
pH	7.2
		Extrusion force (N)	10.8N
Content of NaHA	23.7mg/g
		Degree of sterility	Sterile (SAL is less than or equal to 10)-6）
Osmolarity	321mOsml/kg
		Lidocaine content (%)	0.29%
2, 6-dimethylaniline content	Conform to

In order to ensure that product specifications are maintained over the shelf life of the composition, several studies have been conducted. In addition, the content of 2,6 dimethylaniline was measured to confirm the absence of lidocaine degradation.

Table 2 provides a summary of the stability test results for the compositions prepared as described herein.

TABLE 2

It was found that the composition consistently met the product specifications over a period of 9 months (from the date of manufacture).

Example 4

Stabilization of soft tissue fillers

The following sterilized HA formulations (samples 1-6) were obtained for testing.

Sample 1Is 13.5mg/g of free HA mixture and 5.5mg/g of hydroxypropyl methylcellulose (HPMC).

Sample 2Comprising 5.5-6.5mg/mL of high molecular weight HA (about 4-6 MDa) and having a degree of elasticity (G') of about 200.

Sample 3Are non-commercially available gels made by mixing distinct gel particles with free HA ((80/20, w/w), said HA particles (80%) being obtained by decomposition of "solid" highly cross-linked HA gels, said particles having different shapes and sizes (several microns to several millimeters).

Sample 4Is a cross-linked cohesive HA formulation. Sample 4 had an HA concentration of about 18mg/mL, a degree of crosslinking of less than 6%, a G' of about 60, and a ratio of high molecular weight HA to low molecular weight HA of from about 95% to about 5% to about 100% of high molecular weight HA.

Sample 5Is a cross-linked cohesive HA formulation. Sample 5 had a HA concentration of about 24mg/mL and a degree of crosslinking of about 6%, G'Is about 170 and the ratio of high molecular weight HA and low molecular weight HA is from about 95% to 5% to about 100% high molecular weight HA.

Sample 6Is a cross-linked cohesive HA formulation. Sample 6 had an HA concentration of about 20mg/mL, a degree of crosslinking of about 5%, a G' of about 450, and a ratio of high molecular weight HA to low molecular weight HA of from about 10% to 90%.

Samples 1-6 were all prepared as follows:

test 1: about 20g of each of samples 1-6, respectively, was mixed and homogenized with lidocaine hydrochloride solution. In this test, the pH of the sample gel was essentially neutral during the addition of lidocaine hydrochloride and was not adjusted, for example, by the addition of sodium hydroxide solution. Each sample was then filled into a syringe and autoclaved.

Test 2: about 20g of each of samples 1-6, respectively, was mixed with lidocaine hydrochloride solution, and the pH was adjusted to 7.2 using NaOH solution as described in example 2 above. Each sample was then filled into a syringe and autoclaved.

Test 3: about 20g of each of samples 1-6, respectively, was mixed with an equal amount of WFI to account for dilution effects. No lidocaine was added. Each sample was then filled into a syringe and autoclaved.

Results: for each of the samples in tests 1-3, rheological measurements were made using the rheological measurement equipment described in example 3. The results are shown in figures 1-8 in a generally diagrammatic manner. The symbol and unit definitions in table 3 apply generally to fig. 1-8.

TABLE 3

As a general guideline, when a stable sample containing lidocaine prepared according to test 1 or 2 is treated with a series of shear frequencies, it should exhibit a similar viscosity as a sample prepared according to test 3 without lidocaine.

Both samples 1 and 2 containing lidocaine were found to be unstable to autoclaving and therefore degraded and much less viscous in tests 1 and 2. Figures 1 and 2 particularly illustrate that samples 1 and 2 have reduced stickiness and thus reduced stability to shear forces when the product is prepared with lidocaine, even when the samples are prepared according to test 2, in which the pH adjustment is performed, compared to a product without lidocaine.

Sample 3 was found to be stable to autoclaving in test 2 but unstable in test 1, and samples 4 and 5 were found to be stable to autoclaving only in test 2. Figures 3, 4 and 5 illustrate that samples 3, 4 and 5 are stable when prepared with lidocaine and pH adjusted, but unstable when lidocaine is added and pH is not adjusted accordingly. Fig. 6 illustrates that sample 5, prepared with lidocaine and pH controlled, has similar viscous and elastic properties (G "/G') as sample 5, prepared without lidocaine. When sample 5 was prepared with lidocaine and the pH was not adjusted, its viscosity and elastic properties changed.

Sample 6 was found to be stable to autoclaving in both test 1 and test 2. Fig. 7 illustrates how sample 6, regardless of how it was produced, has a similar viscosity and therefore little shear similarity (comparison) between the preparation methods. Figure 8 further illustrates that sample 6, regardless of how it was produced, retains similar viscous and elastic properties.

Example 5

Kinetics of Release

The following example describes the kinetics of lidocaine release from the cohesive HA gel of the present specification. The purpose of this example is to demonstrate that lidocaine contained in the cohesive HA gel of the present specification can be released freely from the gel when placed in the skin.

Dialysis was performed over different periods of time (approximately 10g of gel was placed in a small dialysis bag and then placed in 30g of water). After each dialysis was stopped at a given time, the gel was homogenized with a spatula (spatula) and the amount of lidocaine was determined by UV method. The final concentration of the dialysate (dialysisbath) corresponds to the theoretical concentration of lidocaine, indicating that lidocaine is free to be released from the gel.

Table 4 illustrates the lidocaine concentration in% (w/w), the correction of the values and the measured values of the% lidocaine released. Further, fig. 9 illustrates the results tabulated in table 4 below. The theoretical equilibrium concentration of lidocaine that would occur if lidocaine were retained in the gel or if it were released freely is shown in fig. 9. As illustrated therein, the data indicate that lidocaine is free released from the gel.

TABLE 4

The lidocaine concentration profile in sample 5 of example 4 (fig. 9) shows that over time, the profile reaches an equilibrium consistent with free release of lidocaine. This in vitro study showed that lidocaine was released freely from the gel and was not retained in the gel once implanted.

Although the invention has been described and illustrated with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and that numerous changes in the combination and arrangement of parts may be resorted to by those skilled in the art without departing from the scope of the invention as hereinafter claimed.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties (e.g., molecular weights), reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual numerical value is incorporated into the specification as if it were individually recited herein. All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

Groupings of optional elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member may be referred to or claimed individually or in combination with other members of the group or other elements found herein. It is contemplated that one or more members of a group may be included in or deleted from a group for convenience and/or patentability reasons. When any such inclusion or deletion occurs, the specification is considered to encompass the modified group and thus satisfies the written description of all markush groups used in the appended claims.

Some embodiments of this invention are described herein, including the best mode known to the inventors for carrying out the invention. Of course, variations of those described embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the invention to be practiced otherwise than as specifically described herein. Accordingly, this invention includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the invention unless otherwise indicated herein or otherwise clearly contradicted by context.

In addition, throughout this specification, many references are made to patents and printed publications. Each of the above-cited references and printed publications is individually incorporated by reference in its entirety into this specification.

The terms "consisting of …" and "consisting essentially of …" may be used in the claims to further limit the particular embodiments disclosed herein. As used in the claims, the transition term (transition term) "consisting of …" whether filed at the time of filing or added at each modification excludes any element, step or ingredient not specifically recited in the claims. The transitional term "consisting essentially of …" limits the scope of the claims to the specifically recited materials or steps and those materials or steps that do not materially affect the basic and novel characteristics. Embodiments of the invention so claimed are described herein, either literally or explicitly, and can be practiced.

Finally, it is to be understood that the embodiments of the invention disclosed herein are illustrative of the principles of the invention. Other modifications that may be applicable are within the scope of the invention. Thus, by way of example, and not limitation, alternative configurations of the present invention may be used in accordance with the teachings herein. Accordingly, the invention is not limited to the invention as shown and described.

Claims (10)

1. A soft tissue filler composition prepared by a process comprising the steps of:

providing an HA component crosslinked by at least one crosslinking agent selected from the group consisting of 1, 4-butanediol diglycidyl ether (BDDE), 1,4-bis (2, 3-epoxypropoxy) butane, 1, 4-diglycidyloxybutane, 1, 2-bis (2, 3-epoxypropoxy) ethylene, and 1- (2, 3-epoxypropyl) -2, 3-epoxycyclohexane or combinations thereof;

adjusting the pH of the HA component to an adjusted pH above 7.5; and are

Adding a solution containing lidocaine hydrochloride to the HA component having the adjusted pH to obtain the soft tissue filler composition.

2. The soft tissue filler composition of claim 1, which is cohesive.

3. The soft tissue filler composition of claim 1, wherein the soft tissue filler composition is sterilized by autoclaving to be in the form of a sterilized HA-based filler composition, and wherein the sterilized composition is stable for at least 6 months at room temperature.

4. The soft tissue filler composition of claim 1, wherein the method further comprises the step of homogenizing the HA component during or after the step of adding the solution comprising lidocaine hydrochloride.

5. The soft tissue filler composition of claim 4, wherein the homogenizing step comprises mixing the composition with controlled shear forces.

6. The soft tissue filler composition of claim 1, wherein the step of providing the HA component comprises: providing a dried uncrosslinked NaHA material, and hydrating the dried uncrosslinked NaHA material in an alkaline solution to obtain an uncrosslinked alkaline NaHA gel.

7. The soft tissue filler composition of claim 6, wherein the pH of the uncrosslinked, alkaline NaHA gel is greater than 8.0.

8. The soft tissue filler composition of claim 7, wherein the pH of the uncrosslinked, basic NaHA gel is greater than 10.

9. The soft tissue filler composition of claim 1, wherein the HA component comprises a high molecular weight HA component and a low molecular weight HA component, wherein the high molecular weight HA component HAs a molecular weight of at least one million Da and the low molecular weight HA component HAs a molecular weight of less than one million Da.

10. An HA-based filler composition prepared by a process comprising the steps of:

providing a dried uncrosslinked NaHA material and hydrating the dried uncrosslinked NaHA material in an alkaline solution to obtain an uncrosslinked alkaline NaHA gel;

crosslinking the uncrosslinked NaHA gel with BDDE to form a crosslinked basic HA composition having an adjusted pH above 7.5;

adding a solution containing lidocaine hydrochloride to the HA component having the adjusted pH to obtain the HA-based filler composition;

homogenizing the HA-based filler composition, thereby forming a homogenized HA-based filler composition; and are

Sterilizing the homogenized HA-based filler composition, thereby forming the HA-based filler composition,

wherein the HA-based filler composition HAs a squeeze force of from 10N to 13N at a squeeze rate of 12.5mm/min and a viscosity of from 5Pa s to 450Pa s when measured at 5 Hz.