The pharmacokinetic interaction between cimetidine and Tamsulosin HCl was investigated. The results indicate significant changes in Tamsulosin HCl clearance (26% decrease) and AUC (44% increase). Therefore, Tamsulosin HCl capsules should be used with caution in combination with cimetidine, particularly at doses higher than 0.4 mg.
Caution should be exercised with concomitant administration of diltiazem & warfarin and Tamsulosin HCl.
Tamsulosin HCl should be used with caution in combination with moderate or strong inhibitors of CYP2D6 (e.g., fluoxetine) or CYP3A4 (e.g., ketoconazole), particularly at doses higher than 0.4 mg.
Caution is needed when used in combination with carbamazepine & phenytoin.
Caution with drugs for male erectile dysfunction (e.g. sildenafil, tadalafil) etc.