Production of adapalene gels

1. A method for producing an adapalene aqueous gel, which method comprises the steps of:

i) formulating a gelling medium A by mixing water, propylene glycol and a preservative agent, and adding a gelling agent thereto;

ii) formulating an adapalene medium B by dispersing adapalene in water, in the presence of a surfactant;

with the proviso that steps i) and ii) are carried out in parallel or any of step i) or ii) is carried out after the other;

iii) adding the adapalene medium B to the gelling medium A; and

iv) adjusting the pH by adding neutralizing agent thereto,

whereby a gel is formed, said adapalene being in a dispersed state in said gel; said adapalene being the sole active ingredient that exhibits a cosmetic or therapeutic effect in said gel; and all steps in said method being conducted at room temperature.

2. The method as defined by claim 1 , wherein the gelling agent is added in step i) after propylene glycol.

3. The method as defined by claim 1 , wherein the pH is adjusted to about 4.7 to 5.3.

4. The method as defined by claim 1 , wherein the preservative agent is dissolved in propylene glycol at room temperature.

5. The method as defined by claim 1 , wherein the preservative agent comprises methylparaben.

6. The method as defined by claim 1 , wherein said medium A also contains a chelating agent.

7. The method as defined by claim 6 , wherein EDTA (ethylene diamine tetraacetic acid) disodium chelating agent is dissolved in water before addition of propylene glycol and the gelling agent.

8. The method as defined by claim 1 , wherein the gelling agent comprises 2-propenoic acid, polymer with 2,2-bis(hydroxymethyl)propane-1,3-diol 2-propenyl ether.

9. The method as defined by claim 1 , wherein the surfactant comprises a poloxamer.

10. The method as defined by claim 9 , wherein the poloxamer comprises Poloxamer 124.

11. The method as defined by claim 1 , wherein the gel comprises adapalene in an amount ranging from 0.01% to 1% by weight.

12. The method as defined by claim 1 , wherein the weight ratio of adapalene/water in the adapalene medium B ranges from 6% to 23%.

13. The method as defined by claim 1 , which comprises the steps of:

i) formulating a gelling medium A by mixing and dissolving EDTA disodium in water, adding propylene glycol and methylparaben, mixing and adding 2-propenoic acid, polymer with 2,2-bis(hydroxymethyl)propane-1,3-diol 2-propenyl ether, wherein the proportion of propylene glycol/water ranges from 4% to 5%;

ii) separately dispersing adapalene in water in the presence of Poloxamer 124, whereby an adapalene slurry medium B is obtained wherein the proportion of adapalene/active phase and the weight ratio of adapalene/water in the adapalene slurry medium B ranges from 6% to 23%;

iii) adding the adapalene slurry medium B to the gelling medium A; and

iv) adding sodium hydroxide to adjust the pH to about 4.7 to 5.3; whereby a gel is formed, said adapalene being in a dispersed state in said gel; said adapalene being the sole active ingredient that exhibits a cosmetic or therapeutic effect in said gel; and all steps in said method being conducted at room temperature.

14. The method as defined by claim 1 , wherein sodium hydroxide is added after step (iii).

15. The method as defined by claim 6 , wherein the chelating agent comprises EDTA sodium.

16. The method as defined by claim 1 , wherein the gel comprises adapalene in an amount of 0.1% to 0.3% by weight.

17. The method as defined by claim 1 , wherein the gel comprises adapalene in the amount of 0.3% by weight.

18. The method as defined by claim 13 , wherein the gel comprises adapalene in an amount of 0.1% to 0.3% by weight.

19. The method as defined by claim 13 , wherein the gel comprises adapalene in the amount of 0.3% by weight.