NL1003992C2 - Therapeutic gel composition for skin treatment - Google Patents

Abstract

A therapeutic gel composition comprises 20-70 wt.% non-neutralised ~a-hydroxy acids (I), 25-77 wt.% demineralised water and 3-5 wt.% "Sepigel 305" (RTM) gelling agent.

Description

Therapeutic gel with non-neutralized alpha hydroxy acids as active components.

This invention relates to a therapeutic gel containing as active components one or more alpha-hydroxy acids in non-neutralized form, i.e. as free organic acid.

The therapeutic effect of alpha-hydroxy acids, such as, for example: lactic acid, citric acid, tartaric acid, glycolic acid and malic acid, has been known for a long time. Alpha hydroxy acids positively affect a variety of skin conditions, including keratoses, hyperkeratoses, ichthyosis, acne, psoriasis, melasma, hyperpigmentation, seborheic eczema and warts. In addition, alpha hydroxy acids have a beneficial effect on scars and aging symptoms of the skin, such as wrinkles and inelasticity.

Non-neutralized alpha hydroxy acids find use in peels, which take advantage of the keratolytic action of alpha hydroxy acids on the stratum corneum of the skin. The degree of penetration into the skin during a peeling with non-neutralized alpha hydroxy acids depends on the concentration of the alpha hydroxy acids, the reaction time and the condition of the patient's skin. At higher concentrations and longer exposure time, penetration can take place into the dermis.

The alpha hydroxy acids are usually not formulated as free organic acid, but as salt. Such salts can be formed by neutralizing alpha hydroxy acids with a suitable organic or inorganic base. Commonly used bases for this application are: ammonia; primary, secondary or tertiary alkylamines; primary, secondary or tertiary alkanolamines; caustic soda and caustic potash. The amine groups of amino acids and peptides are also used for the neutralization of alpha-hydroxy acids. The use of neutralized alpha-35 hydroxy acids allows formulation in normal pharmaceutical and cosmetic carriers, such as creams, ointments and gels.

However, it is known that the alpha hydroxy acids lose all or part of their therapeutic effect when neutralized. This is mentioned, for example, in patent WO 95/03811. The salts that arise after neutralization of alpha-hydroxy acids have a lower penetration potential than 5 non-neutralized alpha-hydroxy acids. As a result, the action of these salts mainly takes place on the surface of the skin.

The use of non-neutralized alpha hydroxy acids in concentrations above 5% implies a pH of the product below 2. Such pH values usually have a destabilizing effect on pharmaceutical and cosmetic carriers, such as creams, ointments and gels.

For the percutaneous administration of non-neutralized alpha-hydroxy acids, liquid preparations based on solvents such as water, ethanol and propylene glycol are often used. Such solutions are applied to the skin with the help of brushes, compresses or cotton swabs. A drawback of liquid alpha-hydroxy acid preparations is that they can drip or splash during the treatment. Drops of a liquid preparation will find a lower point due to the effect of gravity, where they can end up in undesired places such as eyes and scalp hair when treating the face.

The invention aims to make the percutaneous administration of unneutralized alpha hydroxy acids safer and easier. To this end, formulations have been developed in which the non-neutralized alpha-hydroxy acids are brought into gel form. The gel-forming component in the formulation is Sepigel 305®, manufactured by Seppic Company. The invention is described with reference to the formulation mentioned in Example 1.

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Example 1

Gel with un-neutralized alpha-hydroxy acids (pH = 1.0¾: 5

Components: Weight percentages:

Stage A: Deionized water (50.0 - p)% L-Lactic acid (80%) x% 10 Citric acid monohydrate y% L-Tartaric acid z%

Phase B: Seplgel 305® p% 100.0% 15

Where: χ + γ + ζ = 50.0 and 3.0 <p <5.0

The preparation of the formulation 20 mentioned under example 1 takes place at T = 20 ° C and atmospheric pressure. The components listed under Phase A are stirred until all the solid has dissolved and a homogeneous, clear solution is formed. Then Phase B is added to Phase A. This mixture is homogenized for 10 minutes using a turbo mixer with a rotation speed of 23 rads -1. Stirring is performed during homogenization using a suitable planetarium or gate agitator. The mixture is then stirred for 90 minutes, after which a smooth, opaque gel is formed.

The formulation mentioned under example 1 and comparable formulations with alpha-hydroxy acids in weight percentages ranging from 25% to 70% and with Sepigel 305® in weight percentages from 3.0% to 5.0%, yield a gel that has a shelf life of at least 6 months is at T = 20 ° C and at least 3 months at T = 43 ° C. The pH values of these gels range from 35 pH = 1.4 at 30% alpha hydroxy acids to pH = 0.6 at 70% alpha hydroxy acids.

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Claims (3)

1. Therapeutic gel containing as active components one or more alpha hydroxy acids, characterized in that the alpha hydroxy acids are not neutralized, that the concentration of alpha hydroxy acids is 20% to 70% (wt.%), That the solvent is : demineralized water in 25% to 77% (weight percent), which is the gel former: Sepigel 305® in 3.0% to 5.0% (weight percent). 10 Therapeutic gel, as described in claim 1, characterized in that the formulated alpha-hydroxy acids are: L-lactic acid, citric acid and L-tartaric acid, that Sepigel 305® is formulated in 4.0% (wt%). 15 Therapeutic gel, as described in claim 1, characterized in that the following are added: solvents, emulsifiers, emulsifiers, thickeners, preservatives or essential oils. 10 03 99 2