Topical antibiotics for the treatment of acne vulgaris: A critical evaluation of the literature on their clinical benefit and comparative efficacy

Abstract

This review was undertaken to ascertain the clinical benefit of topical antibiotics in the treatment of acne vulgaris by pooling data from different studies. Specifically, we wished to determine whether topical antibiotics could be ranked in order of therapeutic efficacy and to determine the relative efficacy of topical antibiotics compared with oral tetracycline and topical benzoyl peroxide. Of 135 studies published between January 1966 and April 1989, identified using Medline, 62 reported the results of clinical trials of one or more topical antibiotics. Nine additional articles were identified by hand searching through bibliographies of articles already found, and by contacting the manufacturers of topical antibiotics in the UK. A questionnaire was sent to 50 clinical investigators in order to estimate any possible publication bias resulting from contradictory findings of unpublished studies. Study quality was assessed using four primary and five secondary criteria including overall trial design, clinical technique and methods of data analysis. Because of major deficiencies in study methods, 33 trials were excluded from the final data analysis. Disappointingly, almost all of the remaining trials contained defects either of overall trial design or of reporting. In addition, the considerable variations in a number of parameters meant that few meaningful comparisons could be carried out. The results of 15 double-blind, placebo-controlled trials showed that topical erythromycin was effective against inflamed lesions in concentrations ranging from 1% to 4% with or without the addition of zinc. The effectiveness of topical clindamycin, but not topical tetracycline, against inflamed lesions has also been adequately demonstrated. However, none of the topical antibiotics has been shown to be more effective than benzoyl peroxide. The relative efficacy of topical antibiotics and oral tetracycline has not been reliably established. Replies to the questionnaire identified 17 unpublished trials. In only one instance was it clear that non-publication was due to negative results. Whilst this overview has shown that some topical antibiotic preparations are of clinical benefit, further well-designed studies are needed to identify the range of acne severity which responds to such therapy and to determine the relative efficacy of topical antibiotics and oral tetracycline. In future, efforts should be made to standardize as many features of trial design as possible and to ensure that full details of all aspects of the trials are adequately reported. Journals should be more rigorous in their refereeing of dermatological trials.