<p>Concurrent administration of other alfa1-adrenoceptor antagonists could lead to hypotensive effects. No interactions have been seen when Tamsulosin was given concomitantly with either atenolol, enalapril or nifedipine. Concomitant cimetidine brings about a rise and frusemide a fall in plasma levels of Tamsulosin, but as levels remain within the normal range posology need not be changed. No interactions at the level of hepatic metabolism have been seen during in vitro studies with liver microsomal fractions (representative of the cytochrome P450-linked drug-metabolizing enzyme system), involving amitriptyline, salbutamol, glibenclamide, and finasteride. Diclofenac and warfarin, however, may increase the elimination rate of Tamsulosin.</p>