Efficacy and safety of spinosad and permethrin creme rinses for pediculosis capitis (head lice).

Objective: Studies compared spinosad creme rinse and permethrin lice treatment under "actual-use" conditions for pediculosis capitis (head lice).

Subjects And Materials: Two phase-3, multicenter, randomized, evaluator/investigator-blinded studies compared 0.9% spinosad without nit-combing to 1% permethrin with combing (according to product instructions) in 1038 males and females aged > or =6 months. Spinosad-with-combing groups were included for descriptive, noninferential purposes only. Within 391 households, youngest members having > or =3 live lice were designated primary participants. All household members with lice received the same treatment. Participants administered product 1 to 2 times during the 21-day home-use period on the basis of complete lice eradication after a single use or the presence of lice requiring a second treatment. Scalp evaluations were performed at baseline, day 7, and day 14 (and day 21 for participants treated twice). The primary end point was the proportion of lice-free primary participants 14 days after last treatment.

Results: A total of 84.6% (study 1) and 86.7% (study 2) of spinosad-treated participants were lice free versus 44.9% and 42.9% permethrin-treated participants (P < .001). Most spinosad-treated participants required 1 application, whereas most permethrin-treated participants required 2 applications. Few adverse events were reported, but those occurring were mild to moderate, including eye irritation (permethrin), ocular hyperemia, and application-site erythema/irritation (both medications). No laboratory measure changed significantly.

Conclusions: Spinosad, which did not require nit combing, was significantly more effective than permethrin in 2 studies reflecting actual-use conditions, and most spinosad-treated participants required only 1 application. Spinosad is a more convenient and effective treatment for pediculosis capitis.