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

Abstract

Background: 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.

Objective: Combined results from 2 controlled clinical studies were used to evaluate the efficacy of 0.9% spinosad topical suspension in the eradication of scabies.

Methods: 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.

Results: 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.

Limitations: The studies used small sample sizes to assess equivalency.

Conclusions: 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.

Keywords: Natroba; efficacy; pediatric; scabies; spinosad; topical.