Dutasteride: Possible increase in blood conc & decrease in clearance w/ CYP3A4 inhibitors (eg, verapamil & diltiazem). Tamsulosin HCl: Enhanced hypotensive effects w/ BP-reducing drugs including anesth agents, PDE5 inhibitors & other α1-adrenergic blockers. May increase C
max & AUC w/ ketoconazole & paroxetine. May reduce C
max & AUC w/ furosemide. Significant increase in exposure w/ CYP3A4 & CYP2D6 inhibitors. Increased AUC & decreased clearance w/ cimetidine. Warfarin.