Flomax Clinical Pharmacology

Drug Library
Flomax - Clinical Pharmacology [Tamsulosin]

Hepatic Dysfunction

The pharmacokinetics of tamsulosin HCI have been compared in 8 subjects with moderate hepatic dysfunction (Child-Pugh's classification: Grades A and B) and 8 normal subjects. While a change in the overall plasma concentration of tamsulosin HCI was observed as the result of altered binding to AAG, the unbound (active) concentration of tamsulosin HCI does not change significantly with only a modest (32%) change in intrinsic clearance of unbound tamsulosin HCI. Therefore, patients with moderate hepatic dysfunction do not require an adjustment in FLOMAX capsules dosage.

Drug-Drug Interactions

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 Ž , atenolol, or enalapril for at least three months, FLOMAX capsules 0.4 mg for seven days followed by FLOMAX 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 FLOMAX capsules are administered concomitantly with Procardia XL Ž , atenolol, or enalapril.

Warfarin

A definitive drug-drug interaction study between tamsulosin HCI 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.
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 FLOMAX 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.