Efficacy of a fixed clindamycin phosphate 1.2%, tretinoin 0.025% gel formulation (Velac) in the topical control of facial acne lesions

Abstract

BACKGROUND: A formulation containing agents affecting the noninflammatory as well as the inflammatory lesions of acne vulgaris at the same time would probably show a high efficacy and possibly a considerably shortened duration of treatment. One single formulation would simplify drug administration, thereby enhancing patient compliance and possibly therefore leading to improved therapeutic results. OBJECTIVE: The studies were designed to demonstrate that the recently developed Velac® gel formulation (clindamycin phosphate tretinoin gel, CTG) is at least as effective and safe as its component parts extemporaneously formulated in the same gel base in the topical treatment of moderate to severe acne vulgaris. METHODS: A single-blind randomized design was chosen for a comparison of the efficacy of CTG and clindamycin 1.2% gel, and a double-blind randomized design for a comparison of CTG and tretinoin 0.025% gel. The decrease in the numbers from baseline of the various noninflammatory and inflammatory acne lesions and in the acne severity grades and subsequently the efficacy, were determined at weeks 4, 8 and 12 of treatment following a once-daily application regimen. Aspects of safety were assessed in all patients during the entire period of treatment, RESULTS: In the study of efficacy of 78 patients treated with CTG and 77 patients treated with clindamycin phosphate 1.2% gel, the results were in favour of CTG in closed comedones at weeks 4, 8 and 12 of assessment, although statistical significance could only be established at week 4. Significantly greater improvements were also recorded for CTG in the overall acne severity grade at all three assessment points, in the mean total counts of comedones and inflammatory lesions at week 12 and in the total counts of inflammatory and noninflammatory lesions at all three assessment points. No statistically significant differences could be established for open comedones, papules, pustules or nodules at any of the assessment points, or for the mean total number of inflammatory lesions and comedones at weeks 4 and 8, although CTG produced numerically better results in all parameters. The rate of clearance was faster with CTG than with clindamycin phosphate gel in all parameters of noninflammatory and inflammatory lesions. Apparently, the tretinoin component in CTG considerably enhanced the antiacne efficacy of the antibiotic. The incidences of dryness and irritation were about equal in the two treatment groups. A significantly greater reduction in papule counts at all three assessment points was obtained in 76 patients treated with CTG compared with 73 patients treated with tretinoin. Similarly, CTG resulted in a nonsignificantly greater improvement in the mean total number of inflammatory lesions at weeks 4 and 8, and a significantly better effect than tretinoin at week 12. All other assessed parameters of acne severity responded equally well to both CTG and tretinoin. Clearance of the noninflammatory lesions was slower with CTG than with tretinoin, but this was the other way around for the inflammatory lesions. Apparently the antiacne activity of the antibiotic only complemented that of tretinoin in CTG. Irritation, the most frequently reported adverse event, occurred more often in the tretinoin- than in the CTG-treated patients. CONCLUSION: The CTG formulation had an efficacy in moderate to severe acne of the face surpassing that of its individual components in the same gel base. A faster response to CTG than to the component parts indicates that complete clearance of all acne lesions may occur several weeks earlier than with clindamycin or tretinoin. The safety of CTG was considered to be similar to that of clindamycin phosphate and much better than that of tretinoin.