Mucoadhesive thermoreversible compositions

Abstract

The present invention relates to thermoreversible compositions comprising a poloxamer combined with a crosslinked hyaluronic acid of a pharmaceutically acceptable grade, and the use thereof in the treatment of irritated or damaged mucosa and / or skin.

Description

[0001] MUCOADHESIVE THERMOREVERSIBLE COMPOSITIONS

[0002] The present invention relates to thermoreversible compositions comprising a poloxamer combined with a crosslinked hyaluronic acid of a pharmaceutically acceptable grade, and the use thereof in the treatment of irritated or damaged mucosa and / or skin.

[0003] PRIOR ART

[0004] Thermoreversible compositions are liquid-like systems which have a fluid consistency at low temperatures but gel at higher temperatures. Said change of consistency can be reversible, depending on the type of polymer used (B. Jeong et al., Advanced Drug Delivery Review 64 (2012), 154-162) (P. Alexandridis and T.A. Hatton, Physicochem. Eng. Aspects 96 (1995) 1-46; / J. Rassing and D. Attwood, Int. J. Pharm. 13 (1983) 47-55).

[0005] Poloxamers (available on the market under the names Pluronic®, Synperonic® and Kolliphor®) are a class of non-ionic polymers based on ethylene oxide and propylene oxide, which are widely used as surfactants. Aqueous solutions of poloxamers, as from given concentrations, exhibit increased viscosity with a transition from solution phase to gel as the temperature rises. Said property makes poloxamers ideal for thermoreversible formulations, because they can be applied in the form of liquid-like solutions at room temperature, and then convert to gels at the temperature of the skin and / or mucosa.

[0006] An example of phase transition with a consequent increase in viscosity is obtained from an aqueous solution of Poloxamer P 338 at the concentration of 20% w / w at different temperatures:

[0007] As reported by the manufacturers in the corresponding technical information, concentrations of up to 10% Poloxamer P 338 in water exhibit completely different behaviour from that described above, with no transition from solution to gel.

[0008] However, despite their excellent thermosensitivity characteristics, poloxamer-based solutions have limited mucoadhesive properties (Y.Yuan et al., International Journal of Pharmaceutics 430(2012) 114-119).

[0009] Formulations have been proposed that combine poloxamers with mucoadhesive agents such as chitosan, carbomer, cellulose derivatives, alginic acid and hyaluronic acid. Hyaluronic acid is a polysaccharide naturally present in the human body, in particular in the extracellular matrix of the connective tissues, including skin and mucosa. Said polysaccharide has a strong affinity for water, forming a mucoadhesive matrix, which can improve the adherence and residence time of medicaments on the surface to which they are applied. The combination of poloxamers with hyaluronic acid was studied in rheological terms by Mayol, L al., Eur. J. Pharm. Biopharm. 2008, 70, 199 -206.

[0010] EP 2836200 describes mucoadhesive thermoreversible formulations comprising poloxamers combined with mucoadhesive agents, among which hyaluronic acid is cited but not exemplified. Thermoreversible compositions comprising hyaluronic acid and poloxamers are described in WO 2018019881, EP 1862161 (for intra-articular or subcutaneous use) and EP 2 520 279 (gel for dental use). None of said documents cite chemically modified or crosslinked types of hyaluronic acid. US20140005306 describes hydrogels obtained by mixing Pluronic, gelatin A and hyaluronic acid. Gelatin A is said to form covalent bonds with Pluronic and hyaluronic acid.

[0011] DESCRIPTION OF THE INVENTION

[0012] It has now been discovered that the combination of poloxamers with hyaluronic acid pre-crosslinked with panthenol allows the preparation of improved mucoadhesive thermoreversible hydrogels.

[0013] Said hydrogels are useful in pharmaceutical or cosmetic compositions or medical devices having moisturising and soothing properties designed to soothe irritated skin and mucosa.

[0014] The object of the invention is therefore topical compositions in the form of a thermoreversible hydrogel comprising a poloxamer and a hyaluronic acid crosslinked with panthenol or a salt thereof, especially sodium.

[0015] To ensure good compliance, the compositions according to the invention must be solutions with medium-low viscosity at 25°C (between 1000 and 10000 Cps) and be converted to a high-viscosity gel (between 15000 and 50000 Cps) at body temperature (± 37°C).

[0016] The poloxamer is preferably selected from poloxamer 407, 338, 188, 184 and 124 or mixtures thereof, most preferably poloxamer 338 obtainable from D-BASF with the tradename Kolliphor® P 338.

[0017] The poloxamer concentration typically ranges between 13 and 40% by weight, preferably between 15 and 30%, and more preferably between 15 and 20% by weight.

[0018] Hyaluronic acid crosslinked with panthenol is described in EP 3 574 022 Briefly, hyaluronic acid obtained by deproteinisation is hydrated with purified water at 40°C and buffered to pH 7 to obtain a gel which, after acidification at pH 3.5, is reacted with panthenol at 70°C. The reaction mixture is then neutralised and extracted with solvents, and the precipitate is collected, washed, filtered and dried. It is then hydrated in a buffer and the resulting solution is subjected to dynamic dialysis.

[0019] The average molecular weight Mw of crosslinked hyaluronic acids, determined by the HPLC method, can range from 300 to 1500 kDa. A hyaluronic acid crosslinked with panthenol having a high molecular weight of about 1000 kDa is preferably used.

[0020] The concentration of hyaluronic acid crosslinked with panthenol or a salt thereof ranges between 0.01 and 10% by weight, preferably between 0.1 and 1% by weight.

[0021] The compositions according to the invention can also contain technological adjuvants such as antioxidants, antifoaming agents, chelating agents and preservatives / disinfectants together with one or more dermofunctional or pharmacologically active ingredients, such as dried extract of butcher’s broom, sorbitol, marine collagen, chondroitin sulphate and other agents conventionally used for dermatological, mucosal or cosmetic formulations.

[0022] The compositions according to the invention exhibit a liquid-like state with medium- low viscosity, and can be dispensed by vaginal applicators, buccal sprays, enemas, or any other form suitable for topical application to the skin and mucosa, for example in the treatment of vaginal dryness, xerostomia, anal fissures or interstitial cystitis.

[0023] The following examples illustrate the invention in greater detail.

[0024] Example 1: vaginal gel

[0025] Composition

[0026] Preparation

[0027] Poloxamer P 338 is solubilised under slow stirring in about half of the amount of water. The resulting polymer solution is brought to room temperature (about 25°C).

[0028] Crosslinked hyaluronic acid is added under stirring to the remaining amount of water at a temperature of 80°C. Symdiol® 68T is added slowly, again under stirring, to the solution of hydrated hyaluronic acid having medium-low viscosity. When the Symdiol® 68T has been homogenised with the hydrated hyaluronic acid solution, the temperature is returned to 25°C.

[0029] The latter solution is then added to the poloxamer solution, and mixed until a homogeneous solution is obtained.

[0030] Rheological characteristics

[0031] Rheological characteristics have considerable importance, because they can influence the consistency and spreadability of the formulation, as well as its stability.

[0032] Figure 1 shows the viscosity curve of the formulation at 25°C and 40°C, while Figure 2 shows the oscillatory ramp temperature which allows identification of the crossover temperature at which modulus of viscosity G" is equal to modulus of elasticity G', wherein “ modulus of viscosity G" ” means the viscous component of the material, while “ modulus of elasticity G' ” means the structural integrity of the sample.

[0033] The crossover temperature determined is 31.84°C, confirming that the increase in viscosity does not take place at the storage temperature of the product (i.e. room temperature of 25°C), but at the higher temperatures found on the skin and / or in the mucosa. At the physiological temperature of 37°C, the product therefore takes on the form of a gel with mucoadhesive properties.

[0034] Example 2: artificial saliva

[0035] Composition

[0036] Preparation

[0037] The process is similar to that of Example 1; all that changes is the preservative system with potassium sorbate, which is added to the crosslinked hyaluronic acid solution at 80°C.

[0038] Rheological characteristics

[0039] Figure 3 shows the viscosity curve of the formulation at 25°C and 40°C, while Figure 4 shows the curves of elastic modulus G' and viscous modulus G".

[0040] The crossover temperature determined is 34.29°C, confirming that the increase in viscosity does not take place at the storage temperature of the product (i.e. room temperature of 25°C), but at the higher temperatures found on the skin and / or in the mucosa. At the physiological temperature of 37°C, the product therefore takes on the form of a gel with mucoadhesive properties.

[0041] Example 3: enema for treatment of fissures

[0042] Composition:

[0043] Preparation

[0044] The process is similar to that of Example 1 : potassium sorbate and Ruscus extract are added to the crosslinked hyaluronic acid solution at 80°C.

[0045] Rheological characteristics

[0046] Figure 5 shows the viscosity curve of the formulation at 25°C and 40°C, while Figure 6 shows the curves of elastic modulus G' and viscous modulus G".

[0047] The crossover temperature determined is 29.20°C, confirming that the increase in viscosity does not take place at the storage temperature of the product (i.e. room temperature of 25°C), but at the higher temperatures found on the skin and / or in the mucosa. At the physiological temperature of 37°C, the product therefore takes on the form of a gel with mucoadhesive properties.

[0048] Example 4 Solution for the treatment of interstitial cystitis:

[0049] Composition

[0050] Preparation

[0051] The process is similar to that of Example 1 : chondroitin sulphate is added to the crosslinked hyaluronic acid solution at 80°C.

[0052] Rheological characteristics

[0053] Figure 7 shows the viscosity curve of the formulation at 25°C and 40°C, while Figure 8 shows the curves of elastic modulus G' and viscous modulus G". The crossover temperature determined is 29.75°C, confirming that the increase in viscosity does not take place at the storage temperature of the product (i.e. room temperature of 25°C), but at the higher temperatures found on the skin and / or in the mucosa. At the physiological temperature of 37°C, the product therefore takes on the form of a gel with mucoadhesive properties.

[0054] Example 5: In vitro release test: comparison of formulations comprising poloxamers combined or not combined with various types of linear or crosslinked hyaluronic acid.

[0055] The in vitro release characteristics of four thermoreversible gels containing a poloxamer combined or not combined with a linear or crosslinked hyaluronic acid were evaluated (In Vitro Release Test - IVRT). Caffeine, an active ingredient easily quantifiable by liquid chromatography (HPLC), was added to the various formulations.

[0056] Solution A ', presence of a linear hyaluronic acid with a molecular weight of about 1000 kDa

[0057] Solution B: presence of hyaluronic acid crosslinked with propylbi soxy amine

[0058] Solution C: absence of hyaluronic acid

[0059] Solution D: presence of a hyaluronic acid crosslinked with panthenol.

[0060] Four preparations containing caffeine were prepared:

[0061] Solution A: 0.5 g of caffeine, 10 g of Kolliphor ®338, 0.5 g of linear hyaluronic acid, 49 g of water.

[0062] Solution B: 0.5 g of caffeine, 10 g of Kolliphor ®338, 0.5 g of hyaluronic acid crosslinked with propylbi soxy amine, 49 g of water

[0063] Solution C: 0.5 g of caffeine, 10 g of Kolliphor ®338, 49.5 g of water.

[0064] Solution D: 0.5 g of caffeine, 10 g of Kolliphor ®338, 0.5 g of hyaluronic acid crosslinked with panthenol, 49 g of water.

[0065] Franz cells (HDT 1000, Copley), used to evaluate the release profile of an active ingredient in vitro, comprise two compartments: one containing the active ingredient (donor vehicle) and the other containing the receptor solution, separated by an artificial membrane.

[0066] The artificial membrane has a surface area of 1.77 cm2, while the volume of the receptor compartment is 11.0 mL. Each cell is filled with the receptor solution up to the mark on the sampling arm; the solution is maintained under stirring by a magnet at the speed set.

[0067] As the “EMA draft guideline on quality and equivalence of topical products - Annex I IVRT” does not recommend a precise amount of preparation to be placed in the donor compartment, 150 mg of each formulation was applied to the artificial membrane. The membranes are acclimatised to the receptor phase for about 30 minutes before being applied to the cell. The experiment is conducted under occlusive conditions.

[0068] The cell is filled with 11 mL of pre-degassed receptor solution, and maintained at a temperature of 37°C to simulate the conditions found when it is in contact with the mucosa. Air bubbles between the medium and the receptor compartment must be avoided; for that reason, the receptor solution is stirred continuously with a magnetic stirrer at the speed of 400 rpm. At preset times, such as 0.25, 0.5 and 1 hour, 500 pL of sample is taken up from the cell and replaced with fresh solution; sink conditions are thus maintained throughout the experiment.

[0069] The samples taken are subsequently analysed by HPLC.

[0070] To guarantee sink conditions in the cell, caffeine solubility studies were conducted to select the most suitable receptor solution.

[0071] The term “sink conditions” means the ability of the medium to dissolve at least 3 to 10 times the amount of active ingredient present in the dosage form; 3 times sink was tested in this experiment.

[0072] Assuming that, for the in vitro release test, 11 mL of receptor solution is placed in the receptor compartment and 150 mg of preparation is placed in the donor compartment: to obtain 3 times sink conditions, 3.6 mg of caffeine must be dissolved in 11 ml of receptor solution to satisfy the dissolution studies. The caffeine concentration in the solution is 0.33 mg / mL.

[0073] On the basis of the results obtained in the solubility studies, the medium selected as receptor for evaluation of caffeine release consisted of hexylene glycokwater 30:70 p\p, because it guarantees 3 times sink conditions.

[0074] Two different artificial membranes were tested for the solubility studies: a PES membrane with 0.45 pm pores, and a PVDF membrane with 0.45 pm pores.

[0075] The results demonstrate that the maximum amount of caffeine released in one hour was:

[0076] 0.527 mg / cm2 ± 0.090, corresponding to 62.18% of the theoretical amount of caffeine, from the PVDF membranes

[0077] 0.565 mg / cm2 ± 0.093, corresponding to 66.63% of the theoretical amount of caffeine, from the PES membranes. The membrane selected for comparison of the four preparations in terms of IVRT was the PES membrane, as it allows greater caffeine release.

[0078] After selection of the receptor solution and the artificial membrane, the four formulations were compared by IVRT. The comparative data, expressed as the percentage ratio between the amount of caffeine released by the formulation and the theoretical total amount, are presented in the table below:

[0079] The data demonstrate that:

[0080] Preparation C, not containing any hyaluronic acid, is the one that least retains caffeine, which is released more rapidly.

[0081] Preparation B, containing hyaluronic acid crosslinked with propylbisoxyamine, has a retention efficiency slightly greater than that of preparation A containing linear hyaluronic acid (-3%) at the end of the first hour.

[0082] Preparation D, containing hyaluronic acid crosslinked with panthenol, releases a much smaller amount of caffeine in one hour than the other formulations (about 20% less than the formulation without hyaluronic acid; 9% less than the formulation containing linear hyaluronic acid).

[0083] Said test therefore confirms the ability of poloxamer combined with a hyaluronic acid to slow the release of the active ingredient from the formulation; the delayed effect is further enhanced if the hyaluronic acid used is in the form crosslinked with panthenol.

Claims

CLAIMS1. A topical composition in the form of a thermoreversible hydrogel comprising a pol oxamer in combination with a hyaluronic acid crosslinked with panthenol.

2. The composition according to claim 1 wherein the poloxamer is selected from poloxamers 407, 338, 188, 184, 124.

3. The composition according to any one of the preceding claims, wherein the concentration of the poloxamer ranges between 13 and 40% by weight.

4. The composition according to any one of the preceding claims wherein the concentration of the crosslinked hyaluronic acid or salt thereof ranges between 0.01 and 10% by weight.

5. The composition according to any one of the preceding claims further containing technological adjuvants such as antioxidants, antifoaming agents, chelating agents and pre servatives / di sinfectants .

6. The composition according to any one of the preceding claims further containing one or more dermofunctional or pharmacologically active ingredients.

7. The composition according to claims 1-6 for use in the treatment of irritated or damaged mucosa or skin.

8. The composition for use according to claim 7 for the treatment of vaginal dryness, xerostomia, anal fissures or interstitial cystitis.

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