Dutasteride: Possible increase in blood conc & decrease in clearance w/ CYP3A4 inhibitors (eg, verapamil & diltiazem). Tamsulosin HCl: Theoretical risk of enhanced hypotensive effects w/ BP-reducing drugs including anesth agents, PDE5 inhibitors & other α
1 adrenergic blockers. Increased C
max & AUC w/ ketoconazole, paroxetine. Potential significant increase in exposure w/ CYP3A4 & CYP2D6 inhibitors. Decreased clearance & increased AUC w/ cimetidine. Concomitant use w/ warfarin.