Fig. 3.  Effect of rifampicin treatment on plasma concentrations of S-ketamine (A  and B ) and S-norketamine (C  and D ) during and 3 h after a 2-h S(+)-ketamine infusion of 20 mg/h (A  and C ) and 40 mg/h (B  and D ). Values are mean ± SEM. S-ketamine was infused from t = 0 to t = 120 min.