Tamsulosin drug interactions

List of drug interactions
Nifedipine, Atenolol, Enalapril Warfarin Digoxin and Theophylline Furosemide Cimetidine

Nifedipine, Atenolol, Enalapril
In three studies in hypertensive subjects (age range 47-79 years) whose blood pressure was controlled with stable doses of Procardia XL®, atenolol, or enalapril for at least three months, Tamsulosin capsules 0.4 mg for seven days followed by Tamsulosin capsules 0.8 mg for another seven days (n=8 per study) resulted in no clinically significant effects on blood pressure and pulse rate compared to placebo (n=4 per study). Therefore, dosage adjustments are not necessary when Tamsulosin capsules are administered concomitantly with Procardia XL®, atenolol, or enalapril. Return to top

Warfarin
A definitive drug-drug interaction study between tamsulosin HCl and warfarin was not conducted. Results from limited in vitro and in vivo studies are inconclusive. Therefore, caution should be exercised with concomitant administration of warfarin and FLOMAX capsules. Return to top

Digoxin and Theophylline
In two studies in healthy volunteers (n=10 per study; age range 19-39 years) receiving FLOMAX capsules 0.4 mg/day for two days, followed by Tamsulosin capsules 0.8 mg/day for five to eight days, single intravenous doses of digoxin 0.5 mg or theophylline 5 mg/kg resulted in no change in the pharmacokinetics of digoxin or theophylline. Therefore, dosage adjustments are not necessary when a FLOMAX capsule is administered concomitantly with digoxin or theophylline. Return to top

Furosemide
The pharmacokinetic and pharmacodynamic interaction between Tamsulosin capsules 0.8 mg/day (steady-state) and furosemide 20 mg intravenously (single dose) was evaluated in ten healthy volunteers (age range 21-40 years). Tamsulosin capsules had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide. While furosemide produced an 11% to 12% reduction in tamsulosin HCl Cmax and AUC, these changes are expected to be clinically insignificant and do not require adjustment of the FLOMAX capsules dosage. Return to top

Cimetidine
The effects of cimetidine at the highest recommended dose (400 mg every six hours for six days) on the pharmacokinetics of a single Tamsulosin capsule 0.4 mg dose was investigated in ten healthy volunteers (age range 21-38 years). Treatment with cimetidine resulted in a significant decrease (26%) in the clearance of tamsulosin HCl which resulted in a moderate increase in tamsulosin HCl AUC (44%). Therefore, Tamsulosin capsules should be used with caution in combination with cimetidine, particularly at doses higher than 0.4 mg. Return to top