Efficacy and safety of spinosad cream rinse for head lice.

Objective: To determine if, in patients with head lice, spinosad cream rinse is more effective than permethrin. Design: Two identical, multicenter, randomized, evaluator/investigator-blinded, active-controlled trials. Setting: Twelve clinical research centers from the United States. Patients: People older than 6 months with live lice infestation as assessed by an evaluator. Intervention: Cluster randomization with households as clusters. In randomly assigned households, all persons from the same household received 1 of 3 interventions in a 4:4:1 ratio: (1) spinosad, 0.9%, without nit combing (2) permethrin, 1%, with nit combing, or (3) for descriptive, noninferential purposes only, spinosad, 0.9%, with nit combing. Participants self-administered the product 1 or 2 times during a 21-day home-use period: once if lice were completely eradicated after the single use; twice if nymphs or live lice were still present after the first application. Main Outcome Measures: The primary efficacy end point was the proportion of primary participants (defined as the youngest person in the household with 3 live lice present at day 0) who were louse free, as assessed by a trained evaluator, 14 days after the last treatment. The secondary efficacy end point was the proportion within the 2 treatment groups of all of the enrolled subjects (primary plus nonprimary) requiring 1 or 2 treatments. Safety was assessed by analyzing the occurrence of adverse events in all of the participants (primary and nonprimary). Results: Of the 1038 enrolled patients, 949 in 391 households completed the studies. After 1 treatment in study 1, 94.2% of patients receiving spinosad without nitcombing (146 of 155) and 68.1% of those receiving permethrin (62 of 91) were louse free on day 14. After 1 treatment in study 2, 93.1% of patients receiving spinosad without nit-combing (163 of 175) and 62.4% of those receiving permethrin (53 of 85) were louse free on day 14. After 2 treatments, 55.7% (49 of 88) and 64.3% (18 of 28) of spinosad without nit-combing participants were louse free in studies 1 and 2, respectively, compared with 33.3% (55 of 165) and 27.1% (35 of 129) of permethrin participants. The frequency of adverse effects was similar in spinosadand permethrin-treated patients. Authors’ 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.