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Details for Patent: 5,879,716

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Details for Patent: 5,879,716

Title: Methods and compositions for topical delivery of benzoyl peroxide
Abstract:Benzoyl peroxide intended for topical application is incorporated in novel formulations in which it is retained as impregnants inside the pores of porous solid particles or microspheres. The pores form a continuous network open to the exterior of the particles, permitting outward diffusion of the benzoyl peroxide impregnant at a controlled rate depending on the pore size. The impregnated particles are prepared by impregnation of preformed particles with the benzoyl peroxide.
Inventor(s): Katz; Martin A. (Menlo Park, CA), Cheng; Chung H. (San Jose, CA), Nacht; Sergio (Los Altos, CA)
Assignee: Advanced Polymer Systems, Inc. (Redwood City, CA)
Filing Date:Jun 14, 1993
Application Number:08/076,824
Claims:1. A topical composition for the treatment of acne, the composition comprising:

(a) solid particles composed of a cross-linked copolymer of monoethylenically unsaturated monomers and polyethylenically unsaturated monomers and having a cross-linking density from 20% to 80%, wherein said particles contain a continuous noncollapsible network of pores open to the exterior of said particles, are substantially spherical in shape, and have an average diameter of about 1 micron to about 100 microns, a total pore volume of about 0.01 cc/g to about 4.0 cc/g, a surface area of about 1 m.sup.2 /g to about 500 m.sup.2 /g, and an average pore diameter of about 0.001 micron to about 3.0 microns, and

(b) an impregnant comprising benzoyl peroxide retained inside said pores in an amount effective to treat acne when applied to the skin,

wherein retention of said benzoyl peroxide inside said pores reduces irritancy of the composition when compared to application of the same amount of free benzoyl peroxide without loss of acne treatment activity.

2. A topical composition in accordance with claim 1 in which said benzoyl peroxide is retained inside said pores as a solid.

3. A topical composition in accordance with claim 1 in which said benzoyl peroxide is retained inside said pores in a solvent selected from the group consisting of ethers, esters, alcohols, aromatics, and alkanes.

4. A topical composition in accordance with claim 1 in which said solid particles have an average diameter of about 10 microns to about 40 microns, a total pore volume of about 0.1 cc/g to about 2.0 cc/g, a surface area of about 20 m.sup.2 /g to about 200 m.sup.2 /g, and an average pore diameter of about 0.003 micron to about 1.0 micron.

5. A topical composition in accordance with claim 1 in which said solid particles are composed of a cross-linked copolymer of styrene and divinylbenzene.

6. A topical composition in accordance with claim 1 in which said solid particles are composed of a cross-linked copolymer of methyl methacrylate and ethylene glycol dimethacrylate.

7. A topical composition in accordance with claim 1 in which said solid particles are composed of a cross-linked copolymer of 4-vinylpyridine and ethylene glycol dimethacrylate.

8. A topical composition in accordance with claim 1 in which said solid particles are combined with a vehicle to form a composition selected from the group consisting of fluid, semi-solid, and solid compositions.

9. A topical composition in accordance with claim 1 in which said impregnant comprises about 10 to about 40% by weight of the total weight of said solid particles and said impregnant.

10. A topical composition in accordance with claim 1 in which said impregnant further comprises salicylic acid.

11. A method for the treatment of acne, the method comprising applying to the skin a topical composition comprising:

(a) solid particles composed of a cross-linked copolymer of monoethylenically unsaturated monomers and polyethylenically unsaturated monomers and having a cross-linking density from 20% to 80%, wherein said particles contain a continuous noncollapsible network of pores open to the exterior of said particles, are substantially spherical in shape and have an average diameter of about 1 micron to about 100 microns, a total pore volume of about 0.01 cc/g to about 4.0 cc/g, a surface area of about 1 m.sup.2 /g to about 500 m.sup.2 /g, and an average pore diameter of about 0.001 micron to about 3.0 microns, and

(b) an impregnant comprising benzoyl peroxide retained inside said pores in an amount effective to treat acne when applied to the skin,

wherein retention of said benzoyl peroxide inside said pores reduces irritancy of the composition when compared to application of the same amount of free benzoyl peroxide without loss of acne treatment activity.

12. A method in accordance with claim 11 in which said benzoyl peroxide is retained inside said pores as a solid.

13. A method in accordance with claim 11 in which said benzoyl peroxide is retained inside said pores in a solvent selected from the group consisting of ethers, esters, alcohols, aromatics, and alkanes.

14. A method in accordance with claim 11 in which said solid particles have an average diameter of about 10 microns to about 40 microns, a total pore volume of about 0.1 cc/g to about 2.0 cc/g, a surface area of about 20 m.sup.2 /g to about 200 m.sup.2 /g, and an average pore diameter of about 0.003 micron to about 1.0 micron.

15. A method in accordance with claim 11 in which said solid particles are composed of a cross-linked copolymer of styrene and divinylbenzene.

16. A method in accordance with claim 11 in which said solid particles are composed of a cross-linked copolymer of methyl methacrylate and ethylene glycol dimethacrylate.

17. A method in accordance with claim 11 in which said solid particles are composed of a cross-linked copolymer of 4-vinylpyridine and ethylene glycol dimethacrylate.

18. A method in accordance with claim 11 in which said solid particles are combined with a vehicle to form a composition selected from the group consisting of fluid, semi-solid, and solid compositions.

19. A method in accordance with claim 11 in which said impregnant comprises about 10% to about 40% by weight of the total weight of said solid particles and said impregnant.

20. A method in accordance with claim 11 in which said impregnant further comprises salicylic acid.
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