A comparison of the efficacy and tolerability of adapalene 0.1% gel versus tretinoin 0.025% gel in patients with acne vulgaris: a meta-analysis of five randomized trials

The purpose of this meta-analysis was to determine if adapalene 0.1% gel (Differin(R)) provided superior efficacy and better tolerability than tretinoin 0.025% gel in the treatment of acne vulgaris. All comparative studies, both published and unpublished, from the United States and Europe, that fulfilled rigorous protocol criteria (multicentre, randomized, investigator-blind) were used. Five comparative studies met these criteria, In total. the meta-analysis evaluated 900 patients (450 treated with adapalene 0.1% gel, 450 treated with tretinoin 0.025% gel) with mild-to-moderate acne from the combined clinical trials. To avoid study bias, the meta-analysis used an intention-to-treat analysis. Statistical methodology for the meta-analysis included analysis of covariance, analysis of variance and Cochran-Mantel-Haenszel test. All statistical tests were two-sided, with the 0.05 probability level used to establish statistical significance, and 95% confidence intervals used to assess equivalence. Adapalene demonstrated equivalent efficacy to tretinoin in terms of reducing total lesion count. Adapalene demonstrated more rapid efficacy, as evidenced by a significant difference in the reduction of inflammatory and total lesions at week 1. Adapalene also demonstrated considerably greater local tolerability at all evaluation periods. The findings from this meta-analysis suggest that adapalene 0.1% gel constitutes a pharmacologic advance over such classic retinoids as tretinoin for the treatment of acne vulgaris.