[Clinico-experimental studies on the effect of benzoylperoxide]

Clinical and experimental investigations to characterize therapeutic effects of topically applied benzoyl peroxide (5 and 10% in alcohol-free gel formulation) were performed with: quantitative determination of bacteria in the follicular filaments with the cyanoacrylate technique (P. acnes and micrococcaceae); agar diffusion method for bacteriostatic effects; semi-quantitative determination of skin surface lipids (ground glass method); lipid solvent and thin-layer chromatography (free fatty acids vs. triglycerides); scanning electron microscopy of the skin surface; exfoliative cytology with corneocyte counts in a Fuchs-Rosenthal chamber (corneocytes/cm2 skin surface); determination of corneocyte surface are in micrometer2; and a clinical trial concerning efficacy and tolerance of the gel formulation. Topically applied benzoyl peroxide acts antibacterially and keratolytically, has anti-lipolytic activity, reduces bacteria in the follicular infundibula, but does not inhibit sebum production as measured by skin surface lipids. Benzoyl peroxide stimulates the epidermopoiesis with reduction of corneocytes/cm2 from 87,400 +/- 29,000 to 36,000 +/- 19,000 (day 15 of treatment) with diminution in size of corneocytes from 1,018 micrometers2 +/- 74 to 865 micrometers2 +/- 65 vs. 832 micrometers2 +/- 85 (5% vs. 10% benzoyl peroxide). Alcohol-free gels of benzoyl peroxide are better tolerated by acne patients than those containing alcohol, in particular when combined with topical tretinoin (vitamin A acid) treatment.