A Pharmacokinetics (PK) Study in Lice Infested Children 6 Months to 3 Years of Age

Inclusion Criteria: * Subject must be 6 months to 3 years of age, inclusive, when informed consent is signed. * Subject must be infested with head lice as demonstrated by the presence of at least 1 live louse prior to treatment. * Subject is in general good health. * Subject's parent/guardian (caregiver) must be willing and able to bring subject to all study visits as scheduled. * Subject's caregiver must have provided written informed consent (assent is not required due to the young age of the subjects). * Subject's caregiver must agree to comply with the following study restrictions: * will not use any other form of lice treatment (eg, commercial, community/anecdotal, or mechanical/manual) on the subject for the duration of the study, unless directed to do so by study personnel. * will not shampoo, wash, or rinse the subject's hair or scalp until the Day 2 treatment evaluation has been completed. * will not cut or chemically treat subject's hair in the period between screening and follow-up on Day 15. * will use only study-provided shampoo on the subject for the duration of the study. * will follow all study instructions. Exclusion Criteria: * Subjects who have received any OTC or prescription treatment for head lice in the last 2 weeks. * Subjects or subjects' caregivers who are unable to comply with the study obligations and all study visits. * Subjects whose caregivers do not understand the requirements for participation and/or may be likely to exhibit poor compliance, in the opinion of the Investigator. * Subjects with eczema, atopic dermatitis, or other chronic conditions of the scalp and skin. * Subjects with visible skin/scalp condition(s) that are not attributable to head lice infestation, such as an erythema score that is \> 2, blisters, or any other condition that, in the opinion of the investigative personnel or Sponsor, would interfere with the PK, safety and/or efficacy evaluations. * Subjects with a history of allergy to ivermectin or any ingredients commonly included in hair products such as shampoos, hair conditioners, or styling aids. * Subjects with other diagnoses that, in the opinion of the Investigator, would interfere with the PK, safety, and/or efficacy assessments or would preclude study participation. * Subjects who have been treated with a systemic antibiotic within 2 weeks before screening. * Subject currently taking warfarin sodium (Coumadin®) or has taken within 2 weeks before screening. * Subjects who have been enrolled in any clinical study within the past 30 days; subjects may not participate in another study while participating in this study.