A Pharmacokinetic and Safety Study of Moxidectin to Identify an Optimal Dose for Treatment of Children 4 to 11 Years

Inclusion Criteria: 1. Aged 4 to 17 years, inclusive: 1. Cohort I: 12 to 17 years; 2. Cohort II: 8 to 11 years; 3. Cohort III: 4 to 7 years; 2. Live in a region designated by the World Health Organization (WHO) as endemic for O. volvulus infection (World Health Organization, 2019). Specifically, participants will be recruited from the Kpassa sub-district of the Nkwanta North district.The specific communities will include Wii, Jagri-Do, and Azua where mass drug administration with ivermectin for onchocerciasis commenced in October 2017; 3. Willing and able to remain at the study clinic from Screening up to Day 7; 4. Provision of parental or guardian written informed consent and assent / lack of expression of 'deliberate objection' (as appropriate for age); 5. Females of childbearing potential must commit to using a reliable method of contraception as per local family planning guidelines from Baseline (pre-treatment on Day 0) until approximately 6 months after treatment with study drug. Exclusion Criteria: 1. History of serious medical or psychiatric condition which, in the opinion of the investigator, would put the subject at increased risk by participating in the study or jeopardize study outcomes; 2. Known or suspected concurrent clinically significant renal, cardiac, pulmonary, vascular, metabolic (thyroid disorders, adrenal disease), immunological disorders or malignancy, congenital heart disease, chronic lung disease; 3. Has received an investigational product within 28 days or 5 half-lives of Baseline, whichever is longer; 4. Has received ivermectin or any other anti-helminthic treatments within 28 days of Baseline; 5. Has received a vaccination within 7 days of Baseline; 6. Known or suspected hypersensitivity to macrocyclic lactones or excipients used in the formulation of moxidectin; 7. Poor venous access; 8. Unable to swallow tablets (flat oval, 8.0 millimeters (mm) x 4.5 mm x 3.0 mm); 9. Weight: 1. Cohort I (12 to 17 years): \< 30 kg; 2. Cohort II (8 to 11 years): \< 18 kg; 3. Cohort III (4 to 7 years): \< 12 kg; 10. Clinically relevant laboratory abnormalities at Screening, including: 1. Hemoglobin \< 9.5 grams per deciliter (g/dL); 2. Neutrophil (granulocyte) count \< 1.5 x 109/L; 3. Platelet count \< 110 x 109/L; 4. Alanine aminotransferase (ALT) \> 1.5 times the upper limit of normal range (ULN); 5. Total bilirubin \> 1.5 times ULN; 11. Hepatitis B, Hepatitis C, or human immunodeficiency virus (HIV) positive; 12. Known or suspected malaria or other ongoing viral, bacterial, or plasmodium infection at Screening and/or Baseline; 13. Loa loa co-infection; 14. Unwilling, unlikely or unable to comply with all protocol specified assessments; 15. For females of child bearing potential, pregnant or breastfeeding, or planning to become pregnant; 16. Previous enrolment in this study; 17. Is a sibling of another child already enrolled in this study.