Process for preparing a stable emulsion comprising one or more avermectins
A process is described for preparing a stable emulsion that includes at least one avermectin. Also described, is the emulsion thus obtained, especially for use in the treatment of dermatological disorders such as rosacea.
1. A process of preparing a composition in the form of an emulsion comprising 0.01% to 3% by weight of at least one avermectin, relative to the total weight of the composition, the process comprising, successively:
(a) emulsifying an oily phase and an aqueous phases at a temperature from 60° C. to 75° C.;
(b) cooling the resulting emulsion to a temperature from 48° C. to 55° C.;
(c) adding to the emulsion an active phase comprising the at least one avermectin dissolved in a medium comprising at least one glycol; and
(d) cooling the emulsion to a single temperature selected from 42° C. to 47° C.;
(e) maintaining the temperature in (d) for 10 to 20 minutes; and
(f) cooling the emulsion further to a temperature from 30° C. to 40° C.
2. The process according to claim 1 , wherein the at least one avermectin is selected from the group consisting of ivermectin and optical isomers thereof.
3. The process according to claim 1 , wherein the at least one avermectin is present in an amount from 0.1% to 2% by weight, relative to the total weight of the composition.
4. The process according to claim 1 , wherein the at least one avermectin is present in an amount from 0.5% to 1% by weight, relative to the total weight of the composition.
5. The process according to claim 1 , wherein the emulsifying is performed at 65° C.±2° C.
6. The process of claim 1 , wherein the emulsion has a Brookfield viscosity that, when measured after the emulsion has been stored at room temperature for 7 days immediately after manufacturing, does not vary by more than 10% compared to the Brookfield viscosity measured immediately after manufacturing.
7. The process of claim 6 , wherein the Brookfield viscosity of the emulsion, when measured after the emulsion has been stored at room temperature for 7 days immediately after manufacturing, does not vary by more than 5% compared to the Brookfield viscosity measured immediately after manufacturing.
8. The process of claim 1 , wherein the cooling of (b), (d), and/or (f) of the emulsion is uncontrolled.