Adapalene

The Efficacy and Safety of Adapalene Gel 0.3% in the Treatment of Acne Vulgaris: A Randomized, Multicenter, Investigator-Blinded, Controlled Comparison Study Versus Adapalene Gel 0.1% and Vehicle

Pariser DM, et al. Cutis. 2005;76:145-151.

Summary

The authors present a multicenter, randomized, double-blind clinical trial to assess the efficacy of adapalene 0.3% gel in comparison to both adapalene 0.1% gel and vehicle. Two hundred fourteen patients with moderate to moderately severe acne vulgaris of the face were enrolled in the study. Inclusion criteria included a minimum of 20 noninflammatory and 20 inflammatory lesions. Patients were randomized into the 3 treatment groups in a 1:1:1 ratio. Study medication was applied once daily for 12 weeks. Assessment occurred at weeks 1, 2, 4, 8, and 12. Each assessment included lesion counts and a global severity score using the Leeds Revised Acne Grading System. The same clinician performed all assessments for a given patient. Adverse events were recorded at each visit. At 5 of the 11 centers in this study, laboratory evaluation was undertaken, including plasma adapalene levels, complete blood cell counts, urinalysis, and serum chemistries. Of the 214 patients enrolled, 85% completed the study. Analysis was conducted using the intent-to-treat population, Patients in the adapalene 0.3% gel treatment arm had statistically significant reductions in inflammatory, noninflammatory, and total lesion counts compared to both the adapalene 0.1% gel and the vehicle groups. In addition, there was a statistically significant difference in the mean reduction of global severity scores for adapalene 0.3% gel compared to the 0.1% formulation and the vehicle. No serious advents events were noted. Across all groups, reporting of mild to moderate adverse events was similar. The most commonly reported adverse event was dry skin. In addition, erythema occurred more often in the adapalene 0.3% treated group compared with the adapalene 0.1% treated group. No significant changes in laboratory tests were noted. Adapalene was not detected in the plasma at any quantifiable level.

Comment

This was a well-designed, randomized, double-blind, controlled trial adequately powered to detect statistically significant differences in the efficacy of adapalene 0.3% gel in comparison to both adapalene 0.1% gel and vehicle in the treatment of moderate to moderately severe acne vulgaris. Results indicate the superior efficacy of the new adapalene formulation of increased concentration compared to the older formulation and vehicle. In addition to statistically significant decreases in lesion counts at the study's end, adapalene 0.3% gel was found to produce a statistically significant reduction in both total and noninflammatory lesion counts at week 1 compared to both adapalene 0.1% gel and vehicle. Although the data was generated during the study, the authors did not provide results of an analysis of adapalene 0.1% gel compared to vehicle. As adapalene 0.3% gel appears more efficacious than the older formulation, it would be interesting to evaluate its efficacy compared to topical tazarotene and tretinoin formulations.

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