HK1195746B - Intravaginal delivery system - Google Patents

Description

Intravaginal delivery system

Technical Field

The present invention relates generally to intravaginal delivery systems and their uses, and methods of making and using the systems.

In particular, the present invention relates to an intravaginal delivery system for the controlled release of one or more organic acids, such as lactic acid, characterized in that it comprises a combination of an Ethylene Vinyl Acetate (EVA) copolymer and a carboxylic acid polymer, such as for example a methacrylic acid-methacrylate copolymer.

Background

The vagina is a tubular fibromuscular tract leading from the uterus to the outside of the body in females. Healthy vaginas are colonized by a mutually symbiotic flora of microorganisms, in particular lactobacilli, which protect their host from vaginal infections. The acidity of the healthy vagina (pH about 3.8-4.5) in women of childbearing age is due to the degradation of secreted glycogen/glucose into lactic acid and acetic acid by lactobacilli (Boskey et al, 2001). The acidity is detrimental to the growth of many pathogenic microorganisms, including bacteria, protozoa and viruses. However, any imbalance in the vaginal ecosystem can lead to overgrowth of pathogenic microorganisms, resulting in vaginal infections.

Depending on the pathogenic microorganisms involved, there are various types of vaginal infections (vaginitis), such as bacterial vaginitis, vaginal candidiasis and trichomoniasis, and combinations thereof.

Bacterial vaginosis is the most common cause of vaginal infections and is associated with pregnancy complications and an increased risk of sexually transmitted diseases. It is caused by a naturally occurring imbalance of flora wherein the lactobacilli are overgrown by a mixed flora of anaerobic bacteria. In other diagnostic criteria, a pH greater than 4.5 is considered to be indicative of bacterial vaginitis. Current treatment regimens rely on oral or vaginal administration of classical antibiotics such as metronidazole and clindamycin (clindamycin), but the rate of relapse is over 50% within 3 months after first exposure (verstraiten & Verhelst, 2009). Another treatment regimen involves acidifying the vagina with a naturally occurring acid such as lactic or acetic acid. For example, Andersch et al used intravaginal lactic acid gel to treat 42 women with recurrent bacterial vaginosis. After 6 months of treatment 88% of the women in the treatment group had normal vaginal flora, in contrast to 16% of the women in the placebo group (Andersch et al, 1990).

Vaginal candidiasis is a fungal infection of any candida species (yeast), with candida albicans being the most common. Most candida infections are treatable and result in only few complications, such as redness or itching, but in certain populations, such as immunocompromised patients, complications can also be severe and even fatal if not treated in time. External cleansers or internal disorders (hormonal or physiological) can disturb the normal flora in the vagina, leading to overgrowth of candida cells, causing infections. Pregnancy and the use of oral contraceptives have been reported as risk factors. Clinically, candidiasis is commonly treated with antifungal agents (e.g., clotrimazole, nystatin, fluconazole, and ketoconazole). However, candida albicans (c. albicans) can develop resistance to such antifungals, so alternative treatment regimens are desirable.

Trichomoniasis is a sexually transmitted disease of the urogenital tract caused by the single-celled protozoan parasite trichomonas vaginalis. Symptoms include cervical, urethral and vaginal inflammation, which produces itching and burning sensations. Current treatment regimens include the use of antibiotics/anti-protozoan (metronidazole) or anti-parasitic (tinidazole) drugs. However, for most antimicrobial drugs, resistance may occur, emphasizing the need for alternative treatment regimens.

Therefore, alternative treatment regimens for vaginal infections and sexually transmitted diseases (without the use of antibiotics or other kinds of drugs) have been proposed and may exist for the use of acidic compounds (for lowering pH) or naturally occurring vaginal bacterial strains. However, most existing products use gel-like formulations, requiring multiple daily applications, requiring significant effort and liability for the patient. It would therefore be highly advantageous to provide a controlled release product to deliver active ingredients, in particular organic acids, such that multiple daily applications are no longer required, but only once every few days, or even once every few weeks, for example.

It is therefore an object of the present invention to provide an intravaginal delivery system for the controlled release of organic acids, in particular lactic acid.

Although intravaginal delivery systems for the controlled release of active ingredients have been described previously, most of them do not contain organic acids as active ingredients.

For example, WO2006065873 provides an intravaginal flat porous mesh surrounded by a fiber reinforced composite ring comprising an elastomeric copolymer matrix, such as glycolide copolymers, carbonate copolymers and silicone polymers (siliconepolymers). The porous network provides controlled delivery of at least one bioactive agent. Furthermore, any organic acid present in the device is used only as an excipient other than the biologically active agent, and not as the active ingredient itself (as in example 10 of WO 2006065873). US20070196433 provides a two-segment drug delivery device comprising a drug permeable polymeric substance, such as ethylene vinyl acetate copolymer. However, again, no organic acids are mentioned in the active ingredients, but they do include pharmaceuticals, such as antibiotics. WO2009066006 provides an intravaginal delivery system for the controlled release of drugs, in particular drospirenone and estradiol, comprising one or more polymers selected from a long list of possibilities. However, the only exemplified delivery system included the commonly used PEO-b-PDMS (polyethylene oxide-b-poly (dimethylsiloxane)) copolymer. Again, the delivery system may also include an organic acid, but none of the exemplified systems include one or more organic acids as the primary active ingredient.

WO2010133761 provides an intravaginal polymeric delivery system comprising at least one active ingredient including an acidic compound or a beneficial microorganism. Again, however, suitable polymers may be selected from a long list of possible polymers including combinations thereof, the only exemplified polymer combination being the commonly used PEO-b-PDMS (polyethylene oxide-b-poly (dimethylsiloxane)) copolymer.

Clearly, it is not excluded that pharmaceutically relevant levels of organic acids may encounter undesirable reactivity when attempting to incorporate them into certain polymeric environments. Furthermore, to achieve controlled release of the organic acid from the delivery system, the polymeric environment should not only be compatible with the pharmaceutically relevant levels of organic acid present, but should also allow controlled release from the delivery device. Thus, it is not straightforward to employ any available intravaginal delivery system, nor to replace the active ingredient used with one or more organic acids at pharmaceutically relevant concentrations.

To the best of our knowledge, only 1 publication describes an intravaginal delivery system comprising an organic acid as the main active ingredient (WO 2010/133761). In this publication, only the commonly used PEO-b-PDMS (polyethylene oxide-b-poly (dimethylsiloxane)) copolymer is used, into which folic acid is incorporated (example 1). However, no data are provided regarding the folate release profile and therefore there is a question whether the device can be used for controlled release of organic acids. Furthermore, as can be seen from the examples hereinafter, cationic polymers have been found to be unsuitable for the preparation of controlled release delivery systems.

In contrast, we have found that a delivery system comprising one or more EVA (ethylene vinyl acetate) copolymers and one or more carboxylic acid polymers is well suited for the controlled release of organic acids.

Disclosure of Invention

As a first object, the present invention provides an intravaginal delivery system for the controlled release of one or more organic acids, said delivery system being characterized in that: it comprises a combination of one or more Ethylene Vinyl Acetate (EVA) copolymers and one or more carboxylic acid polymers.

In a particular embodiment of the invention, the one or more EVA copolymers are copolymers of ethylene and vinyl acetate comprising aboutIn between, especially comprising about 40% vinyl acetate.

In a further embodiment, the one or more carboxylic acid polymers are selected from the list consisting of methacrylic acid copolymers, cellulose phthalate, carbopol (carbopol), alginate, polylactic acid, hypromellose acetate succinate (HPMCAS), and copolymers thereof, especially copolymers of methacrylic acid.

In a preferred embodiment, the intravaginal delivery system according to the invention comprises a combination of: one or more EVA copolymers, in particular EVA 40; one or more methacrylic acid copolymers, in particular methacrylic acid-methacrylate ester copolymers.

In yet another embodiment, the one or more organic acids are selected from the group consisting of: lactic acid, polylactic acid, glycolic acid, polyglycolic acid, ascorbic acid, folic acid, p-aminobenzoic acid, alginic acid, sorbic acid, tartaric acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, edetic acid and the like, particularly lactic acid and polylactic acid.

In a particular embodiment, the intravaginal delivery system according to the invention comprises between 1-20% wt and about 1-20% wt of said one or more organic acids, in particular contains about 5% wt of said one or more organic acids.

In another specific embodiment, the intravaginal delivery system according to the invention comprises between about 65-75% wt and 65-75% wt of one or more EVA polymers and about 20% wt of one or more carboxylic acid polymers.

In a preferred embodiment, the intravaginal delivery system according to the invention comprises between about 5-10% wt and 5-10% wt of lactic acid, between about 70-75% wt and 70-75% wt of EVA and between about 15-30% wt and 15-30% wt of one or more carboxylic acid polymers.

The intravaginal delivery system according to the invention may be prepared by any suitable method, in particular by extrusion, co-extrusion and/or injection moulding.

The intravaginal delivery system according to the invention may also comprise one or more pharmaceutically active ingredients.

In a further aspect, the present invention provides a method for the intravaginal controlled delivery of one or more organic acids, the method comprising administering an intravaginal delivery system according to the invention.

In a specific embodiment, the present invention provides a method of preventing and/or treating vaginal infections, in particular bacterial infections, said method comprising administering an intravaginal delivery system according to the invention to a patient in need thereof.

The present invention further provides an intravaginal delivery system according to the invention for administration, in particular for vaginal controlled delivery, of one or more organic acids, either in combination with one or more additional active agents or not.

Thus, the present invention provides an intravaginal delivery system according to the invention for use in the prevention and/or treatment of vaginal infections, in particular bacterial infections, more in particular recurrent vaginitis.

The intravaginal delivery system may be used in combination with the administration of one or more additional active agents for the prevention and/or treatment of vaginal infections, in particular bacterial infections, more in particular recurrent vaginitis.

Brief description of the drawings

Fig. 1 and 2: mean mucosal production (mucosall production) and survival of slugs in the 5-day mucosal challenge test.

Detailed description of the invention

In a first aspect, the present invention provides an intravaginal delivery system for the controlled release of one or more organic acids, said delivery system being characterized in that: it comprises a combination of one or more Ethylene Vinyl Acetate (EVA) copolymers and one or more carboxyl polymers.

As used in the context of the present invention, an intravaginal delivery system includes any device suitable for providing controlled intravaginal delivery of one or more organic acids and capable of being prepared from a combination of one or more ethylene-vinyl acetate (EVA) copolymers and one or more carboxylic acid polymers. The delivery system may be in any suitable form, such as, for example, pessaries (vaginal pessaries) or pessaries. The pessary is inserted into the vagina and vaginal wall, fixes its position from which the organic acid is released, and the pessary remains in that position for the entire period of organic acid release.

The delivery system according to the invention may have many shapes, such as wheel, ring, ellipse, spiral, oval, toric, toroidal coil, helical tube, etc. Thus, the term intravaginal ring, as used herein, is also intended to include intravaginal devices having a non-ring-like shape.

The delivery system according to the present invention may be prepared in any desired size depending on the patient, the amount of organic acid delivery required, the particular application, and the like. Generally for adult females, the vaginal ring may typically have a ring diameter as follows: about 35-70 millimeters (mm) and 35-70 mm, preferably about 40-65 mm and 40-65 mm, and most preferably about 50-55 mm and 50-55 mm. The cross-sectional diameter is preferably about 2.0-6.0 mm and 2.0-6.0 mm, more preferably about 3.5 to 5.0 mm, in particular about 4.0 mm.

As used herein, "controlled release (controlled release )" is meant to include any type of release, which is not immediate release. For example, the release of organic acids from an intravaginal delivery system according to the invention may be slow and distributed over a period of time to maintain a certain pH in the vagina. More specifically, the delivery system allows for sustained release of the organic acid for a period of up to 20 days, more specifically up to 7, 10, 14, or 18 days. Thus, the intravaginal delivery system does not have to be changed multiple times per day, as is the case with vaginal gels, but may generally be changed after one or more days (e.g., weekly, or once every 2 weeks, or even once every 1-4 weeks, particularly weekly, or once every 2 weeks).

A copolymer of EVA (ethylene vinyl acetate) as used herein is a copolymer of ethylene and vinyl acetate characterized by: the percentage by weight of vinyl acetate is usuallyThe balance being ethylene. EVA copolymers are particularly soft, elastic and easy to process, and are therefore well suited for the preparation of intravaginal delivery systems. The intravaginal delivery system according to the invention comprises in particular between about 25-40% and 25-40%, more preferably about 30% or 40% of vinyl acetate. Intravaginal delivery systems according to the present invention may comprise any suitable amount of EVA polymer, but preferably comprise between about 65-80% wt and 65-80% wt of one or more EVA polymers.

As used herein, carboxylic acid polymers are meant to include polymers comprising one or more carboxylic acid (-COOH) functional groups. The carboxylic acid polymer is preferably selected from the list consisting of: methacrylic acid (co) polymers, Cellulose Acetate Phthalate (CAP), acrylic acid (co) polymers, alginic acid (alginic acid), polylactic acid, hypromellose acetate succinate (HPMCAS), copolymers or mixtures thereof, and the like, especially copolymers of methacrylic acid. Examples of the carboxylic methacrylic acid copolymer include, but are not limited to, methacrylic acid copolymer L (commercially available under the trade name of) And methacrylic acid copolymer S (commercially available under the trade name）。

The intravaginal delivery system according to the present invention may comprise any suitable amount of carboxylic acid polymer, but in particular comprises from about 10-50% wt and from 10-50% wt of one or more carboxylic acid polymers, and more in particular about 20% wt of one or more carboxylic acid polymers.

In a particular embodiment, the intravaginal delivery system according to the invention comprises between about 65-75% wt and 65-75% wt of one or more EVA polymers and about 20% wt of one or more carboxylic acid polymers.

As used herein, an organic acid refers to an acidic compound, i.e., having a pK_a<6, preferably<5 (at 25 ℃), which contains carbon, oxygen and hydrogen. Preferably, the organic acid according to the invention is a carboxylic acid, comprising C₂-C₆Mono-, di-or tri-carboxylic acids, such as those selected from the list consisting of: lactic acid, polylactic acid, glycolic acid, polyglycolic acid, ascorbic acid, folic acid, p-aminobenzoic acid, alginic acid, sorbic acid, tartaric acid, acetic acid, formic acid, citric acid, oxalic acid, uric acid, edetic acid, adipic acid, succinic acid, and glutamic acid, or a mixture thereof, etc., and lactic acid and polylactic acid are preferable. The intravaginal delivery system according to the invention may comprise said one or more organic acids in any suitable amount, but preferably comprises between about 1-20% wt and 1-20% wt of said one or more organic acids, in particular about 5, 6, 7, 8, 9 or 10% wt of said one or more organic acids. The organic acid may be in a solid or liquid state, but the intravaginal delivery system of the present invention is particularly suitable for the delivery of organic acids in a liquid state.

In a preferred embodiment, the intravaginal delivery system according to the invention comprises between about 5-10% wt and 5-10% wt of lactic acid, between about 70-75% wt and 70-75% wt of EVA and between about 15-30% wt and 15-30% wt of one or more carboxylic acid polymers. In a particular embodiment, the intravaginal delivery system according to the invention comprises between about 5-10% wt and 5-10% wt of an organic acid, in particular lactic acid, between about 70-75% wt and 70-75% wt of EVA, in particular EVA40 or EVA28, and about 20% methacrylic acid copolymer L or Cellulose Acetate Phthalate (CAP).

The intravaginal delivery system according to the invention may be prepared by any suitable method. In general, the organic acid is homogenized with one or more EVA polymers and one or more carboxylic acid polymers, followed by extrusion at a temperature between about 60-160 ℃ and 60-160 ℃, particularly at about 90 ℃. The material is then formed into the desired shape by molding (molding), injection molding (injection molding), rotation/injection molding (rotation/injection molding), die casting, extrusion, co-extrusion, coating extrusion (coating extrusion) and/or hybrid extrusion or other suitable methods. In particular instances, the intravaginal delivery system is prepared by extrusion, coextrusion, or injection molding. More detailed methods for preparing intravaginal delivery systems according to the invention are further provided in the examples below.

The intravaginal delivery system according to the invention comprises therapeutically relevant levels of one or more organic acids, but it may also comprise additional (additional) pharmaceutically active ingredients, in particular those useful in the treatment of vaginal infections. Alternatively, the intravaginal delivery system comprises one or more organic acids as the sole active ingredient, and in case the delivery system is administered, the patient in need thereof may be further treated separately by one or more additional pharmaceutically active ingredients.

Another aspect of the invention is to provide a method for vaginal controlled delivery of one or more organic acids, said method comprising administering an intravaginal delivery system according to the invention. It particularly provides a method for the prevention and/or treatment of vaginal infections, in particular bacterial infections, in particular recurrent vaginitis. Alternatively, the intravaginal delivery system may also be used for the prevention and/or treatment of fungal infections, and/or sexually transmitted diseases.

Vaginitis as used herein refers to any infection involving the vagina. Vaginitis is generally defined as a spectrum of diseases that cause vulvovaginal symptoms such as itching, burning, irritation, and abnormal discharge. The vaginitis according to the invention comprises in particular bacterial vaginitis (vaginiosis), more particularly of the recurrent type. Patients with recurrent vaginitis require regular daily treatment and therefore benefit in particular from a controlled release intravaginal delivery device that can remain in place and provide pharmaceutically active agents, such as lactic acid, over an extended period of time.

The intravaginal delivery system according to the invention is particularly suitable for use as a medicament, in particular for the prevention and/or treatment of vaginal infections, such as bacterial infections, in particular recurrent vaginitis; and for controlled intravaginal delivery of one or more organic acids.

Examples

Example 1: preparation and testing of cationic polymer-containing delivery systems

In this first example, we evaluated whether cationic polymers are suitable for use in preparing controlled delivery systems for organic acids.

Thus, a mixture of 75% by weight of ethylene-vinyl acetate (EVA), 20% by weight of aminoalkyl methacrylate copolymer E (Eudragit E) and 5% by weight of lactic acid was homogenized and fed at 90 ℃ and 60rmp to a co-rotating twin-screw micro-extruder (co-rotating twin-screw mini-extruder). The extrudate was cooled to room temperature and manually cut into 4.5 cm extrudates for pH monitoring testing using a scalpel blade.

The 4.5 cm extrudate was placed in a closed vessel of 3 ml demineralized water, and the pH of the 3 ml demineralized water (demi-water) was initially measured. The vessel was maintained at 37 deg.C +/-0.5 deg.C and the pH was measured every 24 hours over 4 consecutive days and replaced by 3 ml of fresh demineralized water (predetermined pH). The results of this test are shown in table 1.

Table 1: determination of pH value

As is apparent from table 1, the pH increased after each 24 hour period compared to the initial pH value, and based on this fact, lactic acid was introduced, with a reduction in production expected. Thus, these data indicate that cationic polymers, such as Eudragit E, are not suitable for preparing controlled release delivery systems for organic acids, such as lactic acid.

Example 2: preparation and testing of delivery systems for carboxylic acid-containing polymers

It is clear from example 1 that cationic polymers are not suitable for the preparation of controlled release systems for organic acids, and therefore in this example we evaluated whether carboxylic acid containing polymers are suitable for the purpose.

2.1. Different amounts of Ethylene Vinyl Acetate (EVA), methacrylic acid-methyl methacrylate copolymer(s) (II)) And lactic acid were homogenized and fed into a co-rotating twin-screw micro-extruder at 90 ℃ and an rmp of 60. The extrudate was cooled to room temperature and manually cut into 4.5 cm extrudates for pH monitoring testing with a scalpel blade.

The 4.5 cm extrudate was placed in a closed vessel of 3 ml of demineralized water, 3 ml of which was initially measured for pH. The vessel was maintained at 37 deg.C +/-0.5 deg.C and pH was measured every 24 hours during 10-13 consecutive days and replaced by 3 ml of fresh demineralized water (predetermined pH). Three different compositions were tested:

1. placebo extrudate: 80% EVA and 20% Eudragit L

2. Extrudate a: 75% EVA, 20% Eudragit L and 5% lactic acid

3. Extrudate B: 70% EVA, 20% Eudragit L and 10% lactic acid

Table 2: determination of pH value

As is evident from table 2, a significant decrease in pH was observed over each 24 hour period, compared to placebo extrudates (where the pH increased slightly over each 24 hour period), whether for extrudate a or extrudate B, indicating that lactic acid was indeed released from the extrudates. Furthermore, even after 10-13 days, lactic acid appeared to still be released from the extrudate.

2.2. Different amounts of Ethylene Vinyl Acetate (EVA), methacrylic acid-methyl methacrylate copolymer(s) (II)) And lactic acid were homogenized and fed into a co-rotating twin-screw micro-extruder at 90 ℃ and an rmp of 60. The extrudate was cooled to room temperature and manually cut into 4.5 cm extrudates for pH monitoring testing with a scalpel blade.

1. The extrudate was placed in a closed vessel of 3 ml demineralized water;

2. measuring the initial pH;

3. after 24 hours the pH was measured and the medium was changed to fresh demineralised water.

Sample 1: 181.8mg in 3 ml demineralized water

Sky	1	2	3	4	5	6
							Initial pH	3.9	3.95	4.20	4.36	4.64	5.21
After 24 hours	3.03	3.41	3.59	3.63	3.91	4.15

Sample 2: 189.2mg in 3 ml demineralized water

Sky	1	2	3	4	5	6
							Initial pH	3.8	3.73	4.05	4.37	4.99	4.99
After 24 hours	3.04	3.33	3.55	3.58	3.84	4.06

Example 3: 350.4mg in 6 ml demineralized water

Sky	1	2	3	4	5	6
							Initial pH	3.7	3.96	4.32	4.42	5.05	5.12
After 24 hours	3.0	3.41	3.54	3.64	3.85	4.00

It is evident from the data that the pH dropped over each 24 hour period, indicating that acetic acid was indeed released from the extrudate. Furthermore, acetic acid was released from the extrudate even after 6 days.

2.3. Thus, these data indicate that carboxylic acid-containing polymers are suitable for preparing controlled release delivery systems for organic acids (e.g., lactic acid and acetic acid) in contrast to cationic polymers. The polymer not only provides controlled release of the acid, but also incorporates organic acids at sufficiently high levels that release occurs over a longer period of time possible.

Example 3: slug irritation test

Outline of research:

the Slug Mucosal Irritation (SMI) test was originally developed at the Laboratory of pharmaceutical Technology (university of radicle (UGent)) to predict mucosal irritation efficacy of pharmaceutical formulations and ingredients. The test uses a ground slug Arionlusitanicus (terrestrial slug Arionlusitanicus). The body wall of a slug is a mucosal surface composed of different layers. The outer monolayer of columnar epithelium contains ciliated cells, microvilli cells, and mucus secreting cells, overlying the subcutaneous connective tissue. Slugs placed on irritants can produce slime. Additional tissue damage may be induced which results in the release of proteins and enzymes from the mucosal surface. Several studies have shown that the SMI test is a useful tool for evaluating the local tolerance of pharmaceutical formulations and ingredients (Adriaens et al, 1999; Adriaens et al, 2001; Callens et al, 2001; Ceulemans et al, 2001; Adriaens et al, 2003; Dhondt et al, 2004; Weyenberg et al, 2004; Dhondt et al, 2005). A classification predictive model has been developed that distinguishes between stimulation (mucus production) and tissue damage (protein and enzyme release) (Adriaens et al, 2004).

The test was validated "internally" using reference chemicals for eye stimulation (ECETOC ocular reference database). These studies indicate that the SMI test can be used as an alternative to the in vivo eye irritation test (Draize et al, 1944; Adriaens et al, 2002; Adriaens et al, 2005; Dhondt et al, 2005). In addition, there are four multicenter pre-evaluation studies participating in the laboratory that show that the SMI test is a relevant, easily transferable and reproducible alternative test that can be used to predict the eye-stimulating efficacy of chemicals (Adriaens et al, 2008).

The purpose of this study was:

the purpose of this test is to assess the potential irritation of the test item detailed below. Using the target values obtained for the parameters (mucus production), the potential irritation of the test item can be estimated by a predictive model consisting of four broad categories (no, mild, moderate and severe irritation).

And (3) testing items:

-compound a: EVA40 (70%), Eudragit L (30%)

-compound B: EVA40 (75%), Eudragit L (20%), lactic acid (5%)

-compound C: lacta-MedGenix（Wevelgem，BE）

Comparison items:

negative control solids: roller-drying waxy corn starch (DDMW)

Positive control solid: DDWM (80%), sodium lauryl sulfate (20%)

Negative control semi-solid: hydroxyethyl cellulose gel (5%), glycerol (2%) (HEC gel)

Positive control semi-solid: hydroxyethyl cellulose gel (5%), glycerol (2%), Nonoxinol-9 (4%) (HEC/N-9 gel)

The test system comprises:

slugs (Arion lusitanicus), 5 slugs per treatment group. Slugs of the Arion lusitanicus parent, collected along local gardens of the root and alder (belgium), were raised in laboratories adapted to new environment rooms (18-20 ℃). Slugs were housed in plastic containers and fed with lettuce, cucumber, carrot and commercial dog food.

And (3) test design:

a single study was performed. The treatment time was 30 minutes. Once daily for 5 consecutive days.

Experiment design:

preparation of slugs:

slugs weighing between 3 and 6 grams were isolated from the cultures two days before the start of the experiment. The body wall was carefully examined to determine if there was evidence of macroscopic damage. Only slugs with the following characteristics were used for testing purposes: the clear tubercle (tubercle) and the legged surface showed no evidence of injury. Slugs were placed in plastic boxes lined with paper towels moistened with PBS and kept at 18-20 ℃. The body wall of the slug was wetted daily with PBS using a micropipette.

Test procedure liquid:

the efficacy of the test items, negative and positive controls for stimulation and tissue damage was assessed as follows: 5 slugs per treatment group were placed on 20 mg (solid) or 100 mg (semi-solid) test items for 30 minutes per day (contact time) for 5 consecutive days. After every 30 minutes of contact time, slugs were transferred to new petri dishes with membrane filters wetted with 2ml PBS until the next contact period. After the contact period, the mucus production was measured.

And (3) determining an end point:

mucus production

The amount of mucus produced during each contact period was measured as follows: before and after each 30 minute contact period, the petri dishes with test items were weighed. Mucus production is expressed as% (% body weight) of body weight. Slugs were weighed before and after 30 minutes of contact time each.

Classification prediction model

Based on the endpoint of the SMI test, the stimulation efficacy of the defined test item was estimated using a classification predictive model, as shown in table 3.

Table 3: predictive models for the stimulation efficacy of substances with different physical states.

	Solid body	Semi-solid
			Non-irritating	<7%	<15%

Mild in nature	7-12%	15-20%
			Of moderate degree	12-20%	20-25%
Severe (severe)	>20%	>25%

% indicates mucus production, expressed as% body weight

In particular, stimulation efficacy is estimated from total mucus production and is classified into 4 categories (no irritants, mild, moderate and severe), with the threshold depending on the physical state of the formulation (solid or semi-solid). For each slug, the total slime production was calculated as follows: the mucilages produced during each 30 minute contact were summed and then an average of 5 slugs was calculated.

And (4) acceptance standard:

before the test can be considered valid, the following conditions must be met:

solid negative control group (DDWM) should be classified as non-irritating (total mucus production < 7%)

Solid Positive control item (DDWM/SLS 80/20) should be classified as Severe irritancy (total mucus production > 20%)

Semi-solid negative control group (HEC-gel) should be classified as non-irritating (total mucus production < 15%)

Semi-solid positive control (HEC/N-9 gel) should be classified as severely irritating (total mucus production > 25%)

As a result:

the% slime production and dead slugs number were determined over a 5-day period (table 4), and the dead slugs number and average total slime production (MP) were calculated at the end of the 5-day experiment (figure 1).

Table 4: results of the 5-day test

¹Mean ± standard deviation per contact period;²mean ± standard deviation, n =5, MP: the resulting mucus; % bw =% body weight; DDWM = drum-dried waxy corn starch; NC = negative control; SLS = sodium lauryl sulfate; HEC gel = hydroxyethyl cellulose gel 5%, containing 2% glycerol; HEC/N-9gel = hydroxyethylcellulose gel 5%, containing 2% glycerol and 4% nonoxynol-9

First, the acceptance criteria are checked. The total MP for all control items met the criteria described above, and therefore the results of this experiment were considered valid.

The solid negative control slug (DDWM) produced a small amount of mucus at each exposure period and no slugs died from treatment, therefore this substance was classified as not causing irritation (total MP < 7%).

Slugs treated with formulation a or B produced only slightly increased mucus production during each exposure period and, for both formulations, no slug death, so these formulations were also classified as not irritating (total MP < 7%). In addition, the total MP was lower than that of the solid negative control after 5 days. Addition of 5% lactic acid to formulation (B) resulted in only a slight increase in MP compared to formulation a without any lactic acid. However, total MP was still < 7% (critical value between no microstimulation and mild stimulation).

The positive solid control slug (DDWM/SLS 80/20) showed high mucus production during the first 3 days, and only one slug died during the third contact period. There was another death after the 4 th contact period. The positive control slug produced a total MP > 20%, indicating severe irritation of the mucosal surface of the slug.

Three semisolid formulations were also tested. Semi-solid negative control slugs (HEC/Glycerol (Glycerol) 5%/2%) produced only very little mucus per contact period and no slugs died and were therefore classified as not causing irritation (total MP < 15%).

Formulation C (this is a commercially available vaginal lactic acid cream containing 0.5% lactic acid (Lacta)) A considerable amount of mucus production was induced per day, significantly higher than the negative control. Total MP reached 24.3% after 5 days and was therefore classified as moderate stimulation (20% to 25% total MP). One slug dies in the fourth contact period. The positive semi-solid control slug (HEC/glycerol/N-95%/2%/4%) showed high mucus production during the first 2 days and a substantial reduction in mucus production during the third contact period. Four slugs die in the second contact period and the last slug in the series dies after the third contact period. The positive control slug produced total MP of>25% indicates severe irritation of the mucosal surface of the slug.

And (4) conclusion:

solid formulations a and B induced only a slight response in the slugs, and they were even better tolerated than the solid negative controls. Commercially available vaginal lactate cream LactaThe response of (c) was more pronounced and resulted in a classification of moderate irritation.

Example 4: slug irritation test

In this example, 2 additional compositions containing EVA40/Eudragit L and lactic acid were tested and compared to the 75/20/5 composition used in example 3. Outline of the study, control project, test system.

As a result:

during the 5 consecutive days,% slime production and number of dead slugs were determined (table 5) and after the end of the 5 day experiment, the number of dead slugs and the average total slime production (MP) were calculated (figure 2).

And (3) testing items:

-compound a: EVA40 (75%), Eudragit L (20%), lactic acid (5%)

-compound B: EVA40 (72.5%), Eudragit L (20%), lactic acid (7.5%)

-compound C: EVA40 (70%), Eudragit L (20%), lactic acid (10%)

Table 5: results of the 5-day test

¹Mean ± standard deviation per contact period;²mean ± standard deviation, n =5, MP: the resulting mucus; % bw =% body weight; DDWM = drum-dried waxy corn starch; NC = negative control; PC = positive control

First, the acceptance criteria are checked. The total MP of all control items met the above criteria and the results of this experiment were therefore considered valid.

The solid negative control slug (DDWM) produced a rather small amount of mucus during each exposure period and no slug died from treatment, therefore this substance was classified as not causing irritation (total MP < 7%).

The positive control solid formulation (DDWM/SLS 80/20) showed the highest mucus production during all 5 days. One slug dies in the third contact period and the other three slugs die after the fourth contact period. Total MP > 20% indicates severe irritation to mucosal surfaces of slugs.

Slugs treated with formulation a or B produced only slightly increased mucus production during each exposure period and were also free of slug death for both formulations, so these formulations were also classified as not irritating (total MP < 7%).

Slugs treated with formulation C (containing the highest concentration of lactic acid tested (i.e. 10%)) induced a more pronounced response in slugs with a total MP > 7%, but still < 12%, however, again none of the slugs died, so this formulation was classified as causing a mild irritation.

And (4) conclusion:

formulations a and B induced only a slight response in the slugs, and they were even better tolerated than the solid negative control. Formulation C (containing 10% lactic acid) caused higher mucus production compared to formulations a and B, but was still classified as causing only mild irritation.

Reference to the literature

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Claims (16)

1. A controlled release intravaginal delivery system for the controlled release of lactic or acetic acid, the delivery system characterized by: it includes:

lactic acid or acetic acid; and

a combination of one or more Ethylene Vinyl Acetate (EVA) copolymers and a carboxylic acid copolymer selected from the list consisting of methacrylic acid-methacrylate copolymers and Cellulose Acetate Phthalate (CAP).

2. The intravaginal delivery system of claim 1, wherein said one or more EVA copolymers are copolymers of ethylene and vinyl acetate comprising between 25-40% vinyl acetate.

3. The intravaginal delivery system according to claim 1, wherein the one or more EVA polymers are selected from EVA40 or EVA 28.

4. The intravaginal delivery system according to claim 1, comprising: between 1-20% wt of said lactic acid or acetic acid.

5. An intravaginal delivery system according to claim 1, comprising between 65-80% wt of one or more EVA polymers and between 10-50% wt of one or more methacrylic acid-methacrylate copolymers or Cellulose Acetate Phthalate (CAP).

6. The intravaginal delivery system according to claim 1, comprising:

between 5 and 10% wt of lactic acid,

between 70 and 75% wt of said one or more EVA, and

between 15 and 30% wt of methacrylic copolymer L.

7. The intravaginal delivery system according to claim 1, comprising:

between 5 and 10% wt of acetic acid,

between 70 and 75% wt of said one or more EVA, and

between 15-30% wt CAP.

8. The intravaginal delivery system according to claim 1, wherein the intravaginal delivery system is prepared by extrusion or injection molding, or a combination thereof.

9. An intravaginal delivery system according to claim 1, further comprising one or more pharmaceutically active ingredients.

10. The intravaginal delivery system of claim 1, having a ring, oval, spiral, elliptical, or toroidal shape.

11. An intravaginal delivery system according to claim 1 for use as a medicament.

12. An intravaginal delivery system according to claim 1 for the controlled intravaginal delivery of lactic or acetic acid.

13. An intravaginal delivery system according to claim 1 for the prevention and/or treatment of vaginal infections.

14. An intravaginal delivery system according to claim 1, in combination with the administration of one or more additional active pharmaceutical agents, for the prevention and/or treatment of vaginal infections.

15. An intravaginal delivery system according to claim 13, in which the vaginal infection is a bacterial infection.

16. An intravaginal delivery system according to claim 13, in which the vaginal infection is recurrent vaginitis.