Clinical Drug Experience Knowledgebase

Spinosad is a natural mixture of pediculicidal tetracyclic macrolides—spinosyn A and spinosyn D in the ratio of 5:1. It is derived from species of actinomycetes bacteria - Saccharopolyspora spinosa and is a bacterial waste product produced by fermentation on a nutrient food source. It has since long been used as a pesticide and classified by the US Environment Protection Agency as a reduced risk pesticide product. Spinosad has a high level of efficacy for lepidopteran larvae, as well as some Diptera, Coleoptera, Thysanoptera, and Hymenoptera, but has limited to no activity to other insects and exhibits low toxicity to mammals and other wildlife. Spinosad overstimulates nerve cells by prolonging electrical impulse across synapses by acting like acetylcholine. After periods of hyperexcitation, lice become paralyzed and die. Recently, FDA has approved the topical suspension of spinosad 0.9% for treatment of head lice infestation in patients four years of age and older. It is both pediculicidal and ovicidal.   ^NCATS