<prompt> Tadalafil should not be given with:VasodilatorAntibioticsVasoconstrictorsValproate  <response>: Ref. KDT. Page. 190TALADAFIL:More potent and longer acting congener of sildenafilt12 18 hours and duration of action 2436 hours.Acts fasterSide effects, risks, contraindications and drug interactions are similar to sildenafil.Because of its longer lasting action, nitrates are contraindicated for 3648 hours after tadalafil. vasodilators 