Head Lice Infestations

An open-label, single-center trial was conducted over a period of seven days to determine the pharmacokinetic profile of spinosad 1.8% in pediatric subjects with head lice infestation. Fourteen (14) subjects, 4 – 15 years of age, with head lice were enrolled into the trial. All subjects applied a single topical (scalp) treatment of spinosad 1.8% for 10 minutes, after which the test article was washed off, and subjects underwent plasma sampling. Results demonstrated that spinosad was below the limit of quantitation (3 ng/mL) in all samples. Plasma concentration of benzyl alcohol was not determined in these subjects.

An open-label, two-center trial was conducted over a period of 23 days to determine the pharmacokinetic profile of spinosad 0.9% and the ingredient benzyl alcohol in pediatric subjects with a head lice infestation. Twenty-six (26) subjects between 6 months to 4 years of age were enrolled into the study per protocol. All subjects applied a single topical (scalp) treatment of spinosad 0.9% for 10 minutes, after which the test article was washed off, and subjects underwent plasma sampling over a 12 hour period. Plasma spinosad concentrations were below the limit of quantitation (3 ng/mL) in all samples.

Benzyl alcohol was quantifiable (above 1 μg/mL) in a total of 8 plasma samples in 6 out of 26 subjects (25%): four out of 12 subjects in the 6 months to <2 years age group and two out of 14 subjects in the 2 to 4 years age group. The highest observed concentration was 2.37 μg/mL. Benzyl alcohol concentrations at 12 hours post-treatment were below limit of quantification (1 μg/mL) for all subjects.

Scabies Infestations

An open-label multi-center trial was conducted to determine the pharmacokinetic profile of spinosad 0.9% and the ingredient benzyl alcohol in pediatric subjects with scabies infestation. The PK bioavailability study was completed in 19 pediatrics subjects 5 to 16 years of age. All subjects applied a single topical body treatment of spinosad 0.9% from the neck down to the soles of the feet and allowed treatment to remain on the body for a minimum of 6 hours after which the test article was washed off. Subjects underwent plasma sampling over a 12-hour period after treatment. Plasma spinosad concentrations were below the limit of quantification (3 ng/mL) in all samples.

Benzyl alcohol was quantifiable (above 1 μg/mL) in a total of 9 plasma samples in 6 out of 19 subjects (32%): in 3 out of 10 subjects in the 5 to 9 year age group and in 3 out of 9 subjects in the 10 to 16 years age group. The highest observed concentration was 3.94 μg/mL at 0.5 hours post-treatment but was below limit of quantification at 1 hour post-treatment for one subject in the 10 to 16 years age group. There were two subjects with a benzyl alcohol concentration at 3 hours post-treatment with the highest value of 3.53 μg/mL for one subject in the 5 to 9 years age group. Plasma concentrations were below limit of quantification (1 μg/mL) at 3 hours for all other subjects; no subject had measurable concentrations at the 6 and12 hour time points. The mean (SD) Cmax, Tmax, and AUC0-12h values for benzyl alcohol were 2.737 (1.107) μg/mL, 1.42 (1.242) hours, and 19.240 μg∙h/mL, respectively.