Safety, tolerability and pharmacokinetics of emodepside, a potential novel treatment for onchocerciasis (river blindness), in healthy male subjects

AIMS: Emodepside is an anthelmintic, originally developed for veterinary use. We investigated in healthy subjects the safety, and pharmacokinetics of a liquid service formulation (LSF) and immediate release (IR) tablet of emodepside in 2 randomised, parallel‐group, placebo‐controlled, Phase I studies. METHODS: Seventy‐nine subjects in 10 cohorts in the single ascending dose study and 24 subjects in 3 ascending‐dose cohorts in the multiple ascending dose study were enrolled. Emodepside as LSF was administered orally as single 1–40‐mg doses and for 10 days as 5 or 10 mg once daily and 10‐mg twice daily doses, respectively. Pharmacokinetics and safety were assessed up to 21 and 30 days, respectively. In addition, IR tablets containing 5 or 20 mg emodepside were tested in the single ascending dose study. RESULTS: Emodepside as LSF was rapidly absorbed under fasting conditions, with dose‐proportional increase in plasma concentrations at doses from 1 to 40 mg. Terminal half‐life was > 500 hours. In the fed state, emodepside was absorbed more slowly but overall plasma exposure was not significantly affected. Compared to the LSF, the rate and extent of absorption was significantly lower with the tablets. CONCLUSIONS: Overall, emodepside had acceptable safety and tolerability profiles, no major safety concerns, after single oral administration of 20 mg as LSF and after multiple oral administration over 10 days at 5 and 10 mg OD and at 10 mg twice daily. For further clinical trials, the development of a tablet formulation overcoming the limitations observed in the present study with the IR tablet formulation is considered.