Biluron 50 Drug Interactions

There is no evidence of any pharmacodynamic or pharmacokinetic interactions between Bicalutamide and LHRH analogues. In vitro studies have shown that R-bicalutamide is an inhibitor of CYP3A4, with lesser inhibitory effects on CYP2C9, 2C19 and 2D6 activity.
Although clinical studies using antipyrine as a marker of cytochrome P450 (CYP) activity showed no evidence of a drug interaction potential with Bicalutamide, mean midazolam exposure (AUC) was increased by up to 80%, after co-administration of Bicalutamide for 28 days. For drugs with a narrow therapeutic index such an increase could be of relevance. As such, concomitant use of terfenadine, astemizole and cisapride is contraindicated (see Contraindications) and caution should be exercised with the co-administration of Bicalutamide with compounds such as cyclosporin and calcium channel blockers. Dosage reduction may be required for these drugs particularly if there is evidence of enhanced or adverse drug effect. For cyclosporin, it is recommended that plasma concentrations and clinical condition are closely monitored following initiation or cessation of Bicalutamide therapy.
Caution should be exercised when prescribing Bicalutamide with other drugs with may inhibit drug oxidation e.g. cimetidine and ketoconazole. In theory, this could result in increased plasma concentration of Bicalutamide, which theoretically could lead to an increase in side effects.
In vitro studies have shown that Bicalutamide can displace the coumarin anticoagulant, warfarin, from its protein binding sites. There have been reports of increased effect of warfarin and other coumarin anticoagulants when co-administered with Bicalutamide. It is therefore recommended that if Bicalutamide is administered in patients who are concomitantly receiving coumarin anticoagulants, PT/INR should be closely monitored and adjustments of anticoagulant dose considered (see Precautions and Adverse Reactions).