Study on efficacy of 1% permethrin shampoo and 4% dimethicone lotion as pediculicide products used in Iran: a clinical trial

Background: Head lice (Pediculus humanus capitis) are obligate ectoparasites of mankind, and are mainly transmitted head to head directly from one person to another. Human head lice treatment is faced with some challenges such as lack of complete treatment and the need for treatment repeatedly. The aim of this study was to evaluate the efficacy of two pediculicide products (substances used to treat human head lice infestation); 1% permethrin shampoo and 4% dimethicone lotion. Methods: In this clinical trial, 140 cases of head lice infested people that were referred to the urban comprehensive health centers of Qom provincial health center related to Qom University of Medical Sciences and Health Services, Iran, from April to March 2017. The cases randomly were treated with two pediculicide products; 1% permethrin shampoo and 4% dimethicone lotion. The outcome of the treatment included removal of adult human head lice, nymphs, and nits in confirmed human cases at 14 and 21 days after starting treatments were considered. Results: The success rate of human head lice infestation treatment in case of double use (at one-week intervals) with 1% permethrin shampoo and 4% dimethicone lotion was 65.7% and 62.9%, respectively. There was no statistical significance between the therapeutic effects of the two above-mentioned methods (odds ratio=1.22, P=0.59, CI=0.6-2.5). While the recovery rate of men compared to women was 3.8 (P=0.036), it was 3.1 (P=0.05) for housewives compared to students, and in families with one case compared to ones with more than one patient, this rate was found to be 3 (P=0.034). Family size was one of the most important variables that had a significant effect on the therapeutic rate of 1% permethrin shampoo and 4% dimethicone lotion. Conclusion: The findings of this study do not support the reduction in efficacy of 1% permethrin shampoo and 4% dimethicone lotion as pediculicide products.