This was a single-center, phase I, randomized, double-blind, placebo-controlled, first-in-man study. 96 healthy volunteers were enrolled in this 2-part, multi-cohort study. In both Part 1 and Part 2, sequential cohorts were exposed to increasing doses of SPR720. A total of 96 healthy volunteers (n = 8/cohort, 3:1 randomization) received SPR720 (or placebo) as single oral doses ranging from 100 to 2,000 mg or repeat total daily doses ranging from 500 to 1,500 mg for 7 or 14 days. SPR720 was well tolerated at daily doses of up to 1,000 mg for up to 14 days.

A phase I study in healthy adults was conducted to assess the pharmacokinetic, safety, and tolerability profiles of single ascending doses of OPC-167832, as well as the effects of food on its absorption, distribution, and elimination. This phase I study was followed by a phase I/IIa study, in which adult participants with drug-susceptible pulmonary TB were treated for 14 days with ascending doses of OPC-167832 monotherapy.