Neem-silicone lotion and ultrasound nit comb: a randomised, controlled clinical trial treating head louse infestation

Background: A neem-based conditioner lotion (ONC) used against head lice was previously tested clinically and shown to be relatively ineffective. To improve the activity against lice and their eggs, it was reformulated into a silicone vehicle (NNC) as part of a project to improve pediculicidal medical devices. An ultrasound nit comb was also developed to be used in conjunction with the neem lotion to remove louse eggs from the hair. Methods: A single-centre, parallel group, randomised, controlled, open-label community-based clinical study was set up to test the NNC lotion in comparison with a marketed product based on isopropyl myristate and cyclomethicone (IPM/C) with two treatments 7 days apart. In parallel, the lubrication effects of the NNC and ONC lotions were compared in use with the ultrasound comb. Results: For 134 randomised participants (50 NNC, 53 IPM/C, 17 NNC plus comb, and 14 ONC plus comb), the cure rate was 72.0% for NNC and 69.8% for IPM/C (OR 1.112, 95% CI, 0.47 to 2.61). Additional combing gave 82.4% cure using NNC and 28.6% using ONC (OR 11.67; 95% CI 2.13 to 64.04). No difference in efficacy of nit removal was detected although combing with conditioner was physically easier. Conclusions: One percent neem oil in silicone (NNC) is as effective to eliminate head lice as other silicone products. Nit combing is easier using a conditioner lubricant to facilitate sliding of the eggshells along hairs. Trial registration: Current Controlled Trials Registry ISRCTN77673809