With the simultaneous use of the drug with cimetidine,the concentration of tamsulosin in the blood plasma, and with furosemide -is avoided.
Diclofenac and indirect anticoagulants slightly increase the rate of excretion of tamsulosin.
Diazepam, propranolol, trichloromethiazide, chloromadinone, amitriptyline, diclofenac, glibenclamide, simvastatin and warfarin do not change the free fraction of tamsulosin in human plasma in vitro. In its turn tamsulosin also does not change free fractions of diazepam, propranolol, trichloromethiazide and chloromadinone.
In studies in vitro no interaction was found at the level of hepatic metabolism with amitriptyline, salbutamol, glibenclamide and finasteride.
Other alpha 1-adrenoblockers, acetylcholinesterase inhibitors, alprostedil, anesthetics, diuretics, levodopa, antidepressants, beta-adrenoblockers, blockers of "slow" calcium channels, nitrates and ethanol can increase the severity of the hypotensive effect.