ot be used in combination with strong inhibitors of CYP3A4 (e.g., ketoconazole).
The effects of concomitant administration of a moderate CYP2D6 inhibitor (e.g., terbinafine) on the pharmacokinetics of tamsulosin have not been eva luated.
The effects of co-administration of both a CYP3A4 and a CYP2D6 inhibitor with tamsulosin capsules have not been eva luated. However, there is a potential for significant increase in tamsulosin exposure when tamsulosin 0.4 mg is coadministered with a combination of both CYP3A4 and CYP2D6 inhibitors.
Cimetidine: The effects of cimetidine at the highest recommended dose (400mg every 6hours for 6days) on the pharmacokinetics of a single tamsulosin capsule 0.4mg dose was investigated in 10healthy volunteers (age range: 21 to 38years). Treatment with cimetidine resulted in a significant decrease (26%) in the clearance of tamsulosin hydrochloride, which resulted in a moderate increase in tamsulosin hydrochloride AUC (44%).
Alpha Adrenergic Antagonists:Dutasteride: In a single-sequence, crossover study in healthy volunteers, the administration of tamsulosin or terazosin in combination with dutasteride had no effect on the steady-state pharmacokinetics of either alpha-adrenergic antagonist. Although the effect of administration of tamsulosin or terazosin on dutasteride pharmacokinetic parameters was not eva luated, the percent change in DHT concentrations was similar for dutasteride, alone or in combination with tamsulosin or terazosin.
Warfarin: Dutasteride: In a study of 23healthy volunteers, 3weeks of treatment with dutasteride 0.5mg/day did not alter the steady-state pharmacokinetics of the S- or R-warfarin isomers or alter the effect of warfarin on prothrombin time when administered with warfarin.
Tamsulosin: A definitive drug-drug interaction study between tamsulosin and warfarin was not conducted. Results from limited in vitro and in vivo sudies are inconclusive. Therefore, caution should be exercised with concomitant administration of warfarin and tamsulosin.
Nifedipine, Atenolol, Enalapril:Tamsulosin: In 3studies in hypertensive subjects (age range: 47to 79years) whose blood pressure was controlled with stable doses of nifedipine extended-release, atenolol, or enalapril for at least 3months, tamsulosin hydrochloride capsules 0.4mg for 7days followed by tamsulosin hydrochloride capsules 0.8mg for another 7days (n=8 per study) resulted in no clinically significant effects on blood pressure and pulse rate compared with placebo (n=4 per study). Therefore, dosage adjustments are not necessary when tamsulosin is administered concomitantly with nifedipine extended-release, atenolol, or enalapril.
Digoxin and Theophylline:Dutasteride: In a study of 20healthy volunteers, dutasteride did not alter the steady-state pharmacokinetics of digoxin when administered concomitantly at a dose of 0.5mg/day for 3weeks.
Tamsulosin: In 2 studies in healthy volunteers (n=10 per study; age range: 19 to 39years) receiving tamsulosin capsules 0.4mg/day for 2days, followed by tamsulosin capsules 0.8mg/day for 5 to 8days, single intravenous doses of digoxin 0.5mg or theophylline 5mg/kg resulted in no change in the pharmacokinetics of digoxin or theophylline. Therefore, dosage adjustments are not necessary when a tamsulosin capsule is administered concomitantly with digoxin or theophylline.
Furosemide:Tamsulosin: The pharmacokinetic and pharmacodynamic interaction between |
