Drug interaction between St John's Wort and quazepam

• DOI: 10.1111/j.1365-2125.2004.02171.x
• Publication Date: 2004-09-17T08:20:51Z
• Authors: Atsuhiro Kawaguchi; Masami Ohmori; Shu‐ichi Tsuruoka; Kenta Nishiki; Kenichi Harada; Isamu Miyamori; Ryo‐ichi Yano; Toshiaki Nakamura; Mikio Masada; Akio Fujimura
• Keywords: Pharmacodynamics; Midazolam

Aim St John's Wort (SJW) enhances CYP3A4 activity and decreases blood concentrations of substrates. In this study, the effects SJW on a benzodiazepine hypnotic, quazepam, which is metabolized by CYP3A4, were examined. Methods Thirteen healthy subjects took single dose quazepam 15 mg after treatment with (900 day −1 ) or placebo for 14 days. The study was performed in randomized, placebo‐controlled, cross‐over design an interval 4 weeks between two treatments. Blood samples obtained during 48 h period urine collected 24 each quazepam. Pharmacodynamic determined using visual analogue scales (VAS) digit symbol substitution test (DSST) days 13 14. Results decreased plasma concentration. C max AUC 0‐48 significantly lower than those [ ; −8.7 ng ml (95% confidence (CI) −17.1 to −0.2), −55 CI −96 −15)]. urinary ratio 6β‐hydroxycortisol cortisol, reflects activity, also increased dosing (ratio; 2.1 (95%CI 0.85–3.4)). Quazepam, but not SJW, produced sedative‐like VAS (drowsiness; P < 0.01, mental slowness; calmness; 0.05, discontentment; 0.01). On other hand, impaired psychomotor performance DSST test. did influence pharmacodynamic profile Conclusions These results suggest that concentrations, probably enhancing does drug.