North American efficacy and safety of a novel pediculicide rinse, isopropyl myristate 50% (Resultz).

BACKGROUND: Head lice infestations are a major nuisance in school-aged children and are a worldwide public health problem. There are growing concerns about the effectiveness of current treatments owing to increasing resistance, safety, and patient noncompliance. A safe, easy to use, effective alternative is needed. OBJECTIVE: A pediculicide rinse, 50% isopropyl myristate (IPM), was assessed in two phase 2 trials conducted in North America. The first trial was a nonrandomized (proof of concept) trial without a comparator conducted in Winnipeg, Canada. The second trial, conducted in the United States, was an evaluator-blinded, randomized superiority trial comparing 50% IPM rinse with a positive control (RID; pyrethrin 0.33%, piperonyl butoxide 4%). The primary end points were to determine the safety and efficacy of 50% IPM as a pediculicide rinse. METHODS: Subjects meeting inclusion criteria were enrolled in the above-mentioned trials with efficacy end points 7 and 14 days post-treatment. Subjects were also evaluated on days 0, 7, 14, and 21 for the presence of erythema and edema using the Modified Draize Scale. Other comments associated with the safety evaluation (ie, pruritus) were collected. RESULTS: IPM was found to be effective in the proof of concept study and comparator trial using a positive control. IPM was also well tolerated, with minimal adverse events. All adverse events were mild, resolving by completion of the study. CONCLUSION: Data suggest that IPM is a safe and effective therapy for the treatment of head lice in children and adults. IPM's mechanical mechanism of action makes development of lice resistance unlikely.