The purpose of this study is to evaluate the effect of single doses of midazolam on the plasma concentration of a single dose of moxidectin in healthy young adult subjects, and to assess the safety of co-administration of moxidectin and midazolam.

Inclusion criteria:

1. Men or women of nonchildbearing potential (WONCBP) aged 18 to 50 years inclusive at screening.

   WONCBP may be included if they are either surgically sterile (hysterectomy and/or oophorectomy) or postmenopausal for ≥1 year (with follicle-stimulating hormone [FSH] ≥38 mIU/mL) and must have a negative pregnancy test result within 48 hours before administration of test article. Women who are surgically sterile must provide documentation of the procedure by an operative report or by ultrasound. Sexually active men must agree to use a medically acceptable form of contraception during the study and continue it for 12 weeks after test article administration.

2. Body mass index in the range of 18 to 30 kg/m2 and body weight ≥50 kg.

3. Healthy as determined by the investigator on the basis of screening evaluations.

Exclusion criteria:

1. Women of childbearing potential.
2. Presence or history of any disorder that may prevent the successful completion of the study.
3. Any significant cardiovascular, hepatic, renal, respiratory, gastrointestinal, endocrine, immunologic, dermatologic, hematologic, neurologic, or psychiatric disease.