Combination adapalene/clindamycin hastens, improves clearing of inflammatory acne
Paris - Combination topical-antibiotic-plus-retinoid treatment of inflammatory acne using adapalene 0.1 percent gel (Differin) with clindamycin 1 percent lotion offers better efficacy and safety compared with clindamycin 1 percent lotion alone, according to the results of a study presented at the World Congress of Dermatology.
The combination adapalene/clindamycin and clindamycin monotherapy regimens were compared in a 12-week, multicenter, randomized, investigator-masked, vehicle-controlled trial enrolling 249 subjects. The patients applied adapalene or its vehicle gel each evening. They applied clindamycin twice daily, once in the morning and again two minutes after evening application of the topical retinoid or vehicle control.
Efficacy and safety were assessed at follow-up visits conducted after weeks two, four, eight, and 12, and the analyses showed the combination regimen was associated with a significantly faster onset of effect, and greater overall efficacy in clearing inflammatory and non-inflammatory lesions. Significant differences favoring adapalene plus clindamycin were seen as early as week two in analyses of percent reduction in both total and non-inflammatory lesion counts. Those benefits were maintained throughout the study. Beginning at the week eight visit, there was a significant advantage of the combination treatment with regard to percent reduction in inflammatory lesions.
Safety, evaluated by investigator ratings of the severity of erythema, scaling, dryness, and stinging and burning, also showed a significant benefit of the combination treatment. Patients using adapalene plus clindamycin experienced significantly less erythema than their counterparts using the topical antibiotic plus vehicle gel. Other than that, there were no significant differences in local reactions or other reported adverse effects between the investigational groups.
"This study was designed to address a major issue in the contemporary treatment of acne, and that is the therapeutic role of topical retinoids for inflammatory disease," said John Wolf Jr., M.D., an investigator in the study and professor and chair, department of dermatology, Baylor College of Medicine, Houston. "Historically, many dermatologists have used topical retinoids to treat primarily comedonal acne and topical antibiotics to treat primarily inflammatory acne. The results of this study, showing a greater decrease not only in non-inflammatory lesions but also total and inflammatory lesion counts using these two classes of medication concomitantly compared with the antibiotic alone might be unexpected by many clinicians. However, they convey the message that we can use this dual therapy approach to improve our management of patients with inflammatory acne."
The Phase IV study enrolled patients aged 12 years or older who had mild to moderate acne with 10 to 50 inflammatory lesions, 20 to 150 non-inflammatory lesions, and a global acne severity grade of between 2 and 8 based on the Leeds revised acne grading system. There were no significant differences between the two treatment groups in demographic characteristics.
At study conclusion, total lesion count was reduced about 47 percent among patients using the combination treatment compared with only 25 percent in those applying clindamycin plus vehicle (p<0.001). Application of adapalene plus clindamycin was also associated with an approximate 55 percent reduction in inflammatory lesion count and a nearly 45 percent reduction in non-inflammatory lesions. In contrast, patients using clindamycin plus adapalene vehicle experienced an approximate 45 percent reduction in inflammatory lesions and only about a 15 percent decrease in non-inflammatory lesions (p=0.004 and p<0.001, respectively vs. corresponding values in the combination group). The proportions of patients with final acne global severity grades 1 or 2 were also higher among patients using clindamycin plus adapalene compared with the clindamycin plus vehicle group.
Dr. Wolf commented that the development of less erythema in patients using adapalene plus clindamycin might also be surprising to some dermatologists who would anticipate use of two potentially irritating topical agents together would increase local side effects. However, minimization of erythema in the combination treatment group might also be explained by the anti-inflammatory effect of adapalene.
"This observation from the safety evaluation further illustrates the anti-inflammatory activity of topical retinoids, which is not a widely appreciated aspect of their pharmacology. It appears that acting via its anti-inflammatory effect, topical adapalene actually helped to decrease the erythema that occurs with topical clindamycin alone," Dr. Wolf said.
The study was sponsored by Galderma, manufacturer of Differin. Dr. Wolf has no financial interest in Galderma but is a consultant and speaker for the company.