Fig. (4) Effects of various drugs on oxidative Epo B metabolism by human liver microsomes. A pool of human liver microsomes (0.75 nmoles P450) was incubated with 120 µM Epo B in presence of 10µM troleandomycin (TAO), 400µM erythromycin (Eryt), 25µM ciclosporin A (Ci A), 150µM verapamil, 5µM docetaxel, 30µM paclitaxel, 15􀀁M vinblastine, 15µM vincristine, 100µM etoposide (VP16) or 60µM irinotecan. After 60 min the reaction was stopped, Epo B and its metabolite were extracted with dichloromethane and separated by HPLC. Results are calculated as the residual activity and expressed as a percentage of the activity measured in absence of drugs (control).