Herb-drug interaction between Zuojin Pill and venlafaxine in healthy volunteers

Aims: To evaluate the interaction between Zuojin Pill (ZJP), a Chinese herbal formula preparation and antidepressant agent venlafaxine in healthy volunteers. Methods: Here, the potential pharmacokinetic interaction between ZJP and VEN was investigated. In eleven healthy male volunteers with CYP2D6*1/*1 genotypes, the pharmacokinetics of VEN (oral administration of 25 mg per individual) were compared before and after 7 days of administration with ZJP (3.0 g ZJP, Huanglian Zhixiang®, twice daily). Results: ZJP dosing resulted in a statistically significant increase in the mean area under the plasma concentration–time curve zero to infinity (AUC0-∞) of VEN from 247.8 ± 98.5 to 330.2 ± 125.3 ng×h/mL (P < 0.001). Furthermore, VEN clearance significantly decreased from 119.4±59.5 to 88.7±41.2 L/h (P = 0.003) after ZJP intake. However, the AUC0-∞ of VEN active moiety (VEN + ODV) slightly increased by 8.3% after ZJP administration (P = 0.197). In addition, the incidence of VEN-related side effects was significantly (P < 0.05) reduced after ZJP administration. Conclusion: These results suggested that concomitant use of VEN and ZJP could slightly increase the exposures for both VEN and VEN active moieties, accompanied by a decrease in VEN-related side effects. Therefore, rational concomitant use of both drugs would be promising in clinical practice.