Background: Microcomedones representing the clinically non-visible central precursor lesions of acne are induced by sebaceous hyperplasia as well as altered follicular growth and differentiation, and evolve into both comedones and inflammatory lesions. Thus, targeting microcomedone formation is essential in the prevention and therapeutic control of acne.
Objective: The aim of this study was to assess the capacity of adapalene gel, 0.1%, to control the number of microcomedones after a combination treatment followed by a maintenance treatment.
Methods: This was a single-site exploratory study in subjects with a diagnosis of mild to moderate acne vulgaris and the presence of at least 250 microcomedones per cm(2) at screening visit, counted via cyanoacrylate strips (CyASt). During the first 8 weeks, a combination of adapalene gel (0.1%) and benzoyl peroxide gel (2.5%) was applied. During the randomized, investigator-blinded, and vehicle-controlled 12-week maintenance phase, adapalene once daily (QD), or adapalene alternately with its vehicle once daily every other day (QoD), or vehicle QD were applied to the face. CyASt sampling on the forehead was done at baseline, week 8, and week 20. Lesion counting allowing calculating a defined success rate was done at all visits.
Results: A total of 54 subjects entered the combination phase, and 49 subjects were randomized into the maintenance phase: 16 in both the adapalene QD and the QoD group and 17 subjects receiving the vehicle. The microcomedone median count decreased for all groups until week 8 (end of combination phase) from 319 to 157. Microcomedone counts at the end of the maintenance phase (week 20) showed a significant percent difference (P = 0.04) between adapalene QoD (-53.5) and the vehicle (-42.1) and between adapalene QD (-50.6) and the vehicle (P = 0.037) compared with baseline.
Conclusion: The application of adapalene gel, 0.1% monotherapy daily, or alternately every other day, significantly helps to control the microcomedone count during a 12-week maintenance treatment after a previous combination therapy with benzoyl peroxide in patients with mild to moderate acne.