Investigators at multiple sites conducted 2 safety studies of 0.5% ivermectin lotion, a treatment recently approved by the FDA for head lice in children ≥6 months old. The first safety study was an open-label, single- arm pharmacokinetic (PK) study in which children aged 6 months to 3 years with active head lice infestation were enrolled. Each child received treatment with a 10-minute application of ivermectin. Blood samples were collected at specific times for up to 15 days following treatment to measure the magnitude and duration of systemic absorption of ivermectin. Blood was also obtained for complete blood counts (CBC) and liver function tests (LFT). Study participants were evaluated at baseline as well as 8 and 15 days after treatment for scalp pruritis, erythema, and excoriation.
The second safety study was a single-center, evaluator-blinded, within-subject randomized patch application study. Adults 18 to 65 years old were enrolled and randomized to cumulative dermal irritation (CDI) or contact sensitization (CSZ) groups. The CDI group wore 4 patches: 0.5% ivermectin lotion (IVL), control lotion (CL), normal saline (NS), and 0.1% sodium dodecyl sulfate (SDS). The patches were left on for 24 hours at a time and read daily for 21 days. The CSZ group wore IVL and CL patches for 48 hours at a time and received 9 applications over a 3-week period. Participants were assessed by a trained, blinded evaluator. Reactions to the patches for both groups were rated on a scale from 0 (no reaction) to 7 (strong reaction), and evaluations after patch removal in the CSZ group were graded from 0 (no erythema) to 3 (strong erythema).
A total of 30 children with a mean age of 25.8 months were enrolled in the PK study; 93.3% were of Hispanic ethnicity. All blood levels of ivermectin were <1 ng/ml and ivermectin was detectable in only 2 serum samples by 8 days. There were no significant abnormalities detected in CBC or LFT at any time point. There were 6 cases of mild erythema or pruritus of the scalp possibly related to treatment.
For the patch study, 265 adults were enrolled, and outcome data were collected on 35 of these participants randomized to the CDI group and 220 in the CSZ group. Overall, there were 30 mild adverse events among all patch study participants thought to be related to treatment. Mean scores for skin reactions in the CDI group for IVL and CL were significantly lower than scores for NS and SDS. In the CSZ group, there was no erythema noted in the 218 participants; 2 participants had inconclusive determinations.
Based on these results, the authors conclude that 0.5% ivermectin lotion is a safe treatment for head lice infestation in children as young as 6 months old.
Dr Wright has disclosed no financial...