INVESTIGATION OF THE MECHANISM OF ACTION OF 2-PERCENT FUSIDIC ACID LOTION IN THE TREATMENT OF ACNE-VULGARIS

We describe the results of a single-centre, double-blind, vehicle-cont rolled, parallel group study on the quantitative effects of 2% fusidic acid lotion (Fucidin(R) lotion) in facial acne vulgaris. The trial wa s completed by 52 patients aged 15-25 years with mild to moderate acne who had been randomized to either Fucidin(R) Lotion (n = 25) or its b ase (n = 27). Primary outcome measures included colony counts of Propi onibacterium acnes and micrococcaceae and measurements of skin surface lipid free fatty acids and sebum excretion rate. Clinical assessment was based on the acne grade, count of inflamed and non-inflamed lesion s and evidence of a primary irritant dermatitis. There was a variable but gradual reduction in lesion counts with the maximum improvement at 12 weeks for inflamed lesions, where the reduction was 19.9% for fusi dic acid and 24.7% for the placebo. The noninflamed lesions decreased by 10.8% in the fusidic acid group and increased by 15.9% in the place bo group; this difference was not statistically significant. Although the fusidic acid reduced the micrococcaceae count by 1 log cycle, infe rring adequate compliance, there was no reduction in the counts of P. acnes, surface free fatty acids or sebum excretion rate. This study ha s failed to explain the mechanism of action of topical fusidic acid.