Dutasteride: Increased serum conc w/ verapamil or diltiazem, ritonavir, indinavir, nefazodone, itraconazole, ketoconazole. Tamsulosin: May potentially cause symptomatic hypotension w/ PDE5 inhibitors eg, sildenafil, tadalafil, vardenafil. Enhanced hypotensive effects w/ drugs that can reduce BP, including anesth agents, PDE5 inhibitors, & other α
1-adrenoceptor antagonists. Increased C
max & AUC w/ ketoconazole & paroxetine. Decreased clearance & increased AUC w/ cimetidine. Increased elimination rate w/ diclofenac & warfarin.