Comparison of a topical benzoyl peroxide gel, oral minocycline, oral doxycycline and a combination for suppression of P-acnes in acne patients

Four groups of ten acne patients each received one of the following treatments for 1 month: (1) minocycline-'D', 100 mg twice daily; (2) doxycycline monohydrate, 100 mg twice daily; (3) 6% benzoyl peroxide-zinc gel twice daily; (4) minocycline-'D', 100 mg twice daily and 6% benzoyl peroxide-zinc gel twice daily Suppression of Propionibacterium acnes was assessed by the detergent scrub method after 2 and 4 weeks of treatment. Minocycline-'D' had a far greater ability to suppress P. acnes than doxycycline. Minocycline-'D' resulted in almost a 2-log decrease in P. acnes compared with less than 1-log decrease with doxycycline, Benzoyl peroxide-zinc gel was also more efficacious than doxy-cycline, As expected, the combination of minocycline-'D' and benzoyl peroxide-zinc gel was substantially more effective than the comparator treatments. The greater therapeutic efficacy of minocycline-'D' in acne cannot be fully explained by its antibacterial activity. Evidence is presented to show that minocycline has a wide spectrum of pharmacologic activities, including antiinflammatory effects, which explains its increasing therapeutic applications in a variety of unrelated disorders.