Safety, tolerability, and pharmacokinetics of oral (S)-oxiracetam in Chinese healthy volunteers: A randomized, double-blind, controlled phase I study

(S)-oxiracetam is the major active enantiomer of oxiracetam, which is being developed for dementia. This trial was designed to evaluate the safety, tolerability, and pharmacokinetics of oral (S)-oxiracetam in healthy Chinese volunteers.A randomized, controlled, double-blind and dose-escalation design was used in this Phase I trial, which consisted of a single-ascending-dose (SAD) study (400-2000 mg) and a multiple-ascending-dose (MAD) study (400-1600 mg). Blood, urine and feces samples were collected for pharmacokinetic analysis. Safety was evaluated by monitoring adverse events (AEs).AEs in both studies were mild or moderate in severity and dose-independent. In the SAD study, no chiral transformation was observed. 55.03% and 36.16% of (S)-oxiracetam was excreted unchanged in urine and feces, respectively. Exposures exhibited dose-proportional increases over the range of 400 to 1600 mg but almost unchanged from 1600 to 2000 mg. (S)-oxiracetam was absorbed rapidly, reaching a peak at 0.75-1.00 h, and t1/2 was 6.12-6.60 h. Food had no effect on AUC, but prolonged Tmax to 3.00 h. In the MAD study, steady-state was observed on day 5. Mild accumulations were observed after 7 days of repeated dosing.(S)-oxiracetam was safe and tolerated with favorable pharmacokinetic profiles at all study doses, providing dosing evidence for further efficacy evaluation.