Hydrogel of chitosan carboxyalkylamide, preparation thereof and cosmetic and dermatological use thereof
View Patent ↗The present invention relates to a hydrogel of chitosan carboxyalkylamide, characterised in that it has a pH value close to that of the skin, comprised between 6.5 and 7.2, and in that the chitosan carboxy-alkylamide is constituted by 40 to 90 mole % of D-glucosamine N-carboxyalkylamide units of formula (I) where n represents an integer ranging from 1 to 8, from 60 to 10 mole % of protonated D-glucosamine units, and from 5 to 15 mole % of N-acetyl-D-glucosamine units. The present invention also relates to a dehydration product of such a gel and the cosmetic and/or dermatological utilisation of the gel and the dehydration product.
1. A hydrogel of chitosan carboxyalkylamide, having a pH value between 6.5 and 7.2, said chitosan carboxyalkylamide being constituted by
from 40 to 90 mole %, relative to the total number of (A) and (B) units, of D-glucosamine N-carboxyalkylamide units of formula (I) ((A) units)
where n represents an integer ranging from 1 to 8, or a physiologically acceptable base addition salt thereof,
from 60 to 10 mole %, relative to the total number of (A) and (B) units, of protonated D-glucosamine units of formula (II) ((B) units)
and 5.5 obtained by the addition of an organic acid of formula R—COOH, where R represents a C 1-4 alkyl group,
reaction of the acid addition salt of chitosan in aqueous solution thus obtained with 0.5 to 1 mole, per mole of D-glucosamine units ((B) units), of an anhydride of an organic diacid of formula HOOC—(CH 2 ) n —COOH where n represents an integer comprised between 1 and 8, then
adjustment of the pH of the reaction solution thus obtained to a value between 6.5 and 7.2 by the addition of a physiologically acceptable base.
2. The hydrogel according to claim 1 , wherein R represents a methyl group.
3. The hydrogel according to claim 1 , having a pH between 6.8 and 7.0.
4. The hydrogel according to claim 1 , wherein the concentration of chitosan carboxyalkylamide is between 0.5 and 3% by weight.
5. The hydrogel according to claim 1 , which further comprises from 0.1 to 40% by weight, of at least one polyol.
6. The hydrogel according to claim 1 , which further comprises a water-glycerine extract of calendula officinalis.
7. The hydrogel according to claim 1 , wherein said hydrogel is sterile.
8. The hydrogel according to claim 1 , which is packed in the form of a unit dose.
9. A process for the preparation of a hydrogel according to claim 1 , comprising the following consecutive stages
preparation of an acidic aqueous solution of a chitosan having a deacetylation level between 85 and 95%, the said solution having a pH between 4.5
10. A process of using the hydrogel according to claim 1 for the cosmetic treatment of first degree burns and of non-weeping, superficial second degree burns comprising the application of said hydrogel to the burn area consisting of first degree burns and of non-weeping, superficial second degree burns consisting of first degree burns and of non-weeping, superficial second degree burns.
11. An anhydrous product based on chitosan carboxy-alkylamide obtained by the dehydration of the hydrogel according to claim 1 .
12. The anhydrous product according to claim 11 , as a medicament intended for the treatment of deep, weeping second degree burns or of third degree burns.
13. The anhydrous product according to claim 11 , as a medical device intended for the treatment of deep, weeping second degree burns or of third degree burns.
14. A dermatological composition containing an anhydrous product according to claim 11 .
15. A cosmetic composition containing an anhydrous product according to claim 11 .
wherein R represents a C 1-4 alkyl residue, and
from 5 to 15 mole %, relative to the total number of (A), (B) and (C) units, of N-acetyl-D-glucosamine units ((C) units).
16. The hydrogel according to claim 5 , wherein the polyol is glycerol.