Maintenance
therapy after remission of
inflammation is strongly recommended in the guideline for the treatment of
acne vulgaris published by the Japanese Dermatological Association. One advantage of continuing maintenance
therapy is the alleviation of atrophic
scarring. This study investigated the efficacy of maintenance
therapy using
adapalene 0.1%/
benzoyl peroxide 2.5% gel and
benzoyl peroxide 2.5% gel, and its effects on atrophic
scarring. Overall, 126 patients were randomized to the
adapalene/
benzoyl peroxide group (n = 40),
benzoyl peroxide group (n = 44), and control group (without maintenance treatment drugs; n = 42), and 111 of these completed a trial lasting 24 weeks. As the primary endpoint, the treatment success rate (the percentage of patients in whom the number of inflammatory lesions was maintained at ≤10) was 89.2% in the
adapalene/
benzoyl peroxide group, 87.5% in the
benzoyl peroxide group, and 47.4% in the control group. Compared with the control group, the success rates were significantly higher in the
adapalene/
benzoyl peroxide and
benzoyl peroxide groups (P = 0.0006 for both). As one of the secondary endpoints, the rate of change in the number of atrophic
scars showed significant improvement from the baseline in the
adapalene/
benzoyl peroxide and
benzoyl peroxide groups at week 24 (P = 0.0004 and P < 0.0001, respectively). Although the three-dimensional image analysis parameters did not change significantly from the baseline in the
adapalene/
benzoyl peroxide and
benzoyl peroxide groups at week 24, significant worsening was noted in the control group (P = 0.0276 for affected area, P = 0.0445 for volume, and P = 0.0182 for maximum depth).
Adverse drug reactions were noted in three patients in the
adapalene/
benzoyl peroxide group (7.5%) but not in the
benzoyl peroxide group. These findings suggest that maintenance
therapy using
adapalene 0.1%/
benzoyl peroxide 2.5% gel and
benzoyl peroxide 2.5% gel is effective in preventing the worsening of
scars in Japanese patients with
acne vulgaris.