Pharmacokinetics and safety of imiquimod 5% cream in the treatment of molluscum contagiosum in children.

Imiquimod cream 5%, a toll-like receptor 7 agonist, induces alpha-interferon upon topical application, prompting off-label usage to treat children with molluscum contagiosum. We conducted an open-label study to measure serum drug concentration in children aged 2-12 years with extensive molluscum contagiosum (> or = 10% total body surface area). Dependent on extent of subject disease and weight, one to three packets (12.5 mg imiquimod per packet) were applied per dose, three times per week for 4 weeks. Serum imiquimod and metabolite concentrations were measured at pre dose and 2, 4, and 8 hours postdose 1 and dose 12. Thirty children were screened; 22 children (64% boys; 91% white; mean age 6.2 +/- 2.87 years; median involved body area treated 13.5%) were enrolled. Peak serum imiquimod concentrations following single and multiple dosing were low (< 10 ng/mL). Imiquimod concentrations increased 2- to 3.5-fold with multiple dosing. After single and multiple dosing, peak serum imiquimod (Pearson correlation r = 0.4989 and 0.7219, p < 0.05 both, respectively) and area under the serum concentration-time curve values (r = 0.4989 and 0.7219, p < 0.05 both, respectively) correlated with dose normalized for body weight (mg/kg). Systemic drug levels were low after single and multiple doses of imiquimod 5% cream in children.