The safety and efficacy of clindamycin phosphate foam 1% versus clindamycin phosphate topical gel 1% for the treatment of acne vulgaris

Journal of Drugs in Dermatology, Jan-Feb, 2005 by Alan R. Shalita, Judith A. Myers, Lincoln Krochmal, Alex Yaroshinsky

Mean Percent Reduction in Lesion Counts

The other primary efficacy endpoint analyzed was the mean percent reduction in total, inflammatory, and noninflammatory lesion counts at the end of treatment. Results of these analyses are shown in Figure 3. The difference between the clindamycin foam and clindamycin gel groups in the mean percent reductions in the 3 lesion counts from baseline to Week 12 (end of treatment) was estimated. The lower limit for each confidence interval was 3.03%, -0.97%, and 3.25% for total, inflammatory, and noninflammatory lesions, respectively. As these lower limits were all greater than the set lower noninferiority limit of -11%, the efficacy of clindamycin foam was not inferior to that of clindamycin gel based on this endpoint.

Given that noninferiority was established statistically, additional nonparametric analyses were performed, which showed that the efficacy of clindamycin foam was superior to that of clindamycin gel for all 3 lesion counts (Figure 3). The difference between the clindamycin foam and clindamycin gel groups in the mean percent reduction in total lesion counts was 7.1% (P = .0014). The difference between these 2 groups in the mean percent reduction in inflammatory lesion counts was 4.0% (P = .0478), and in noninflammatory lesion counts was 8.1% (P = .0037).

Efficacy Analyses Comparing Clindamycin Foam with Vehicle Foam

The efficacy of clindamycin foam was also compared to that of its vehicle. A significantly greater proportion of patients attained treatment success at Week 12 in the clindamycin foam group (31%) than in the vehicle foam group (18%; P = .0025), establishing clindamycin foam as superior to its vehicle for this endpoint (Figure 2). Superiority of clindamycin foam over its vehicle was also demonstrated for the mean percent reduction of all 3 lesion counts (total, inflammatory, and noninflammatory; all P <.05, data not shown).

Safety Evaluations

In general, clindamycin foam was well tolerated. Overall, 268/1026 patients (26%) had at least 1 adverse experience (regardless of relationship to the study drug). A total of 111/286 patients (29%) in the clindamycin foam group, 95/385 patients (25%) in the clindamycin gel group, 40/127 patients (31%) in the vehicle foam group, and 22/128 patients (17%) in the vehicle gel group reported adverse experiences. There was no significant difference in the incidence of adverse experiences among the treatment groups (P = .2004). Additionally, most of these experiences were mild or moderate in severity and transient in nature, with the most commonly reported being nasopharyngitis (42/1026; 4%).

Treatment-related adverse experiences were reported by 29/386 patients (8%) in the clindamycin foam group, 10/385 patients (3%) in the clindamycin gel group, 16/127 patients (13%) in the vehicle foam group, and 6/128 patients (5%) in the vehicle gel group (Table 3). The difference in the incidence of treatment-related adverse experiences between the active treatment groups was significant (P = .0018). Compared with the clindamycin foam group, the incidence of treatment-related adverse experiences reported for the vehicle foam group was significantly higher (P = .0789). In all treatment groups, treatment-related adverse experiences occurred predominantly at the application site and included burning, desquamation, pruritus, rash, and unspecified reactions. Application site burning was the only treatment-related adverse experience that occurred with a frequency greater than 5% in any treatment group (6% of clindamycin foam patients, 1% of clindamycin gel patients, 7% of vehicle foam patients, and 2% of vehicle gel patients; P < .0001). Only 1 patient, treated with clindamycin gel, reported a severe study drug-related application site adverse experience that included dryness, irritation, and pain.