Abstract: AIM: To evaluate the tolerability of (S)-ornidazole in healthy volunteers. METHODS: It is a randomized, blinded, placebo-controlled single-center clinical study. Fowrty-eight healthy volunteers enrolled the study. Thirty-eight healthy volunteers were randomly divided into four groups to attend single-dose tolerability trial (250, 500, 1000, 1500 mg, respectively). Ten healthy volunteers entered multi-dose tolerability trial for 7 days [1000 mg (S)-ornidazole, Qd]. Two healthy volunteers of each group were given placebo.Vital signs, electrocardiogram and serum biochemical indicators were observed before and after (S)-ornidazole administration and adverse effects were recorded. RESULTS: In the study, there were no abnormal findings in vital signs, electrocardiogram and serum biochemical indicators.20 healthy volunteers experienced mild adverse effects of dizziness, fatigue, drowsiness nausea and so on. CONCLUSION: (S)-ornidazole tablet is safe for healthy volunteers at daily dose of 250 to 1000 mg

Key words: (S)-ornidazole, Single-dose, Multi-dose, Tolerability trial