Spinosad at 0.9% in the treatment of scabies: Efficacy results from 2 multicenter, randomized, double-blind, vehicle-controlled studies

Abstract

BackgroundScabies is a contagious skin disease resulting from Sarcoptes scabiei infestation. There are no approved over-the-counter treatments, and approved prescription products have disadvantages, including potential resistance. Spinosad, an insecticide derived from fermentation of a soil actinobacterium, shows promise as a potential treatment agent.ObjectiveCombined results from 2 controlled clinical studies were used to evaluate the efficacy of 0.9% spinosad topical suspension in the eradication of scabies.MethodsEach study included index subjects (the youngest household members with active scabies) and up to 5 other members in each household. Subjects applied 0.9% spinosad or vehicle once. Primary efficacy was the percentage of index subjects with complete cure on day 28. Additional efficacy included clinical cure, microscopic cure, and lesion counts.ResultsSpinosad at 0.9% is not equivalent to vehicle in the percentage of index subjects achieving complete cure on day 28 (78.1% vs 39.6%, respectively; P < .0001; n = 206). Additional efficacy analyses confirmed the consistent treatment effect of 0.9% spinosad. No safety signals were observed.LimitationsThe studies used small sample sizes to assess equivalency.ConclusionsSpinosad at 0.9% performed better than vehicle in the treatment of scabies in these studies of subjects of 4 years of age or older following 1 application of study drug. Scabies is a contagious skin disease resulting from Sarcoptes scabiei infestation. There are no approved over-the-counter treatments, and approved prescription products have disadvantages, including potential resistance. Spinosad, an insecticide derived from fermentation of a soil actinobacterium, shows promise as a potential treatment agent. Combined results from 2 controlled clinical studies were used to evaluate the efficacy of 0.9% spinosad topical suspension in the eradication of scabies. Each study included index subjects (the youngest household members with active scabies) and up to 5 other members in each household. Subjects applied 0.9% spinosad or vehicle once. Primary efficacy was the percentage of index subjects with complete cure on day 28. Additional efficacy included clinical cure, microscopic cure, and lesion counts. Spinosad at 0.9% is not equivalent to vehicle in the percentage of index subjects achieving complete cure on day 28 (78.1% vs 39.6%, respectively; P < .0001; n = 206). Additional efficacy analyses confirmed the consistent treatment effect of 0.9% spinosad. No safety signals were observed. The studies used small sample sizes to assess equivalency. Spinosad at 0.9% performed better than vehicle in the treatment of scabies in these studies of subjects of 4 years of age or older following 1 application of study drug.

Topics & Concepts