Multicenter randomized controlled trial on combination therapy with 0.1% adapalene gel and oral antibiotics for acne vulgaris: Comparison of the efficacy of adapalene gel alone and in combination with oral faropenem

We conducted a randomized controlled trial in patients with acne vulgaris with moderate to severe inflammatory lesions. The patients were assigned to the following three treatment groups: group A received monotherapy with 0.1% topical adapalene gel for 4 weeks; group B received combination therapy with 0.1% topical adapalene gel and 600 mg oral faropenem for 2 weeks followed by 0.1% topical adapalene gel alone for 2 weeks; and group C received combination therapy with 0.1% topical adapalene gel and 600 mg oral faropenem for 4 weeks. The result of the analysis indicated that the percentage reduction in inflammatory lesion counts after 2 weeks of treatment was significantly higher in groups B and C than in group A (P < 0.05). After 4 weeks of treatment, group C showed significantly higher percentage reduction in inflammatory lesion counts than in groups A and B (P < 0.05), whereas no significant difference was noted between the latter two groups. Adverse reactions included dryness and irritation at the adapalene application sites that were observed in 10.1% of cases (16/158 patients) and diarrhea and loose stool because of oral faropenem that were observed in 7.5% of cases (8/106 patients). Taken together, our results suggest that combination therapy with oral antibiotics and adapalene results in earlier improvement in patients with moderate to severe inflammatory acne compared to the application of adapalene alone, and that 4 weeks of the combination therapy is preferable to 2 weeks of treatment.