Bicalutamide

7. DRUG INTERACTIONS Clinical studies have not shown any drug interactions between bicalutamide and LHRH analogs (goserelin or leuprolide). There is no evidence that bicalutamide induces hepatic enzymes. In vitro studies have shown that R-bicalutamide is an inhibitor of CYP 3A4 with lesser inhibitory effects on CYP 2C9, 2C19 and 2D6 activity. Clinical studies have shown that with co-administration of bicalutamide, mean midazolam (a CYP 3A4 substrate) levels may be increased 1.5-fold (for C max ) and 1.9-fold (for AUC). Hence, caution should be exercised when bicalutamide is co-administered with CYP 3A4 substrates.

In vitro protein binding studies have shown that bicalutamide can displace coumarin anticoagulants from binding sites. PT/INR should be closely monitored in patients concomitantly receiving coumarin anticoagulants and bicalutamide. Adjustment of the anticoagulant dose may be necessary [see Warnings and Precautions (5.2) and Adverse Reactions (6.2) ]. • R-bicalutamide is an inhibitor of CYP 3A4; therefore, caution should be used when bicalutamide is co-administered with CYP 3A4 substrates. (7) • PT/INR should be closely monitored in patients already receiving coumarin anticoagulants who are started on bicalutamide. (7)

8.1. Pregnancy Risk Summary Bicalutamide tablets are contraindicated for use in pregnant women because it can cause fetal harm. Bicalutamide tablets are not indicated for use in females. There are no human data on the use of bicalutamide tablets in pregnant women. In animal reproduction studies, oral administration of bicalutamide to pregnant rats during organogenesis caused abnormal development of reproductive organs in male fetuses at exposures approximately 0.7 to 2 times the human exposure at the recommended dose ( see Data ).

Data Animal Data In an embryo-fetal development study in pregnant rats dosed during the period of organogenesis from gestation days 6-15, male fetuses had reduced anogenital distance at doses of 10 mg/kg/day and above (approximately 0.7 to 2 times the human exposure at the recommended dose). In a pre- and post-natal development study, female rats were dosed from gestation day 7-16 and allowed to litter and rear their offspring to weaning. Male offspring of rats receiving doses of 10 mg/kg/day (approximately 0.7 times the human exposure at the recommended dose) and above, were observed to have reduced anogenital distance.

In a peri- and post-natal development study, female rats were dosed from gestation day 16 to lactation day 22 and allowed to litter and rear their offspring to weaning. Survival and weights of offspring during lactation were reduced for litters from maternal rats receiving doses of 250 mg/kg/day (approximately 2 times the human exposure at the recommended dose). Male offspring of rats receiving doses of 10 mg/kg/day (approximately 0.7 times the human exposure at the recommended dose) and above, were observed to have reduced anogenital distance, smaller secondary sex organs, cryptorchidism and hypospadias resulting in an inability to mate and impregnate their female partners.

Female offspring of rats receiving doses of 10 mg/kg/day (approximately 0.7 times the human exposure at the recommended dose) and above had reduced pregnancy rates.