Dutasteride: Increased serum conc w/ moderate CYP3A4 & P-gp inhibitors (eg, verapamil, diltiazem) & CYP3A4 inhibitors (eg, ritonavir, indinavir, itraconazole, nefazodone, oral ketoconazole). Tamsulosin: Enhanced hypotensive effects w/ anaesthetic agents, PDE5 inhibitors & other α
1- adrenoceptor antagonists. Increased C
max & AUC w/ strong CYP3A4 inhibitors (eg, ketoconazole), strong CYP2D6 inhibitors (eg, paroxetine). Decreased clearance & increased AUC w/ cimetidine. Possible increased elimination rate w/ warfarin & diclofenac.