dutasteride/tamsulosin

7.5 Furosemide Tamsulosin Tamsulosin had no effect on the pharmacodynamics (excretion of electrolytes) of furosemide. While furosemide produced an 11% to 12% reduction in tamsulosin hydrochloride C max and AUC, these changes are expected to be clinically insignificant and do not require adjustment of the dose of tamsulosin [see Clinical Pharmacology ( 12.3 ) ] .

Mechanism: Furosemide can slightly decrease the levels of tamsulosin in your body, but it does not change how well the water pill works.

What to do: No dose adjustments are necessary because the interaction is not considered clinically important.

7 DRUG INTERACTIONS There have been no drug interaction trials using dutasteride and tamsulosin hydrochloride capsules. Because of the potential for drug-drug interactions, use caution when prescribing a dutasteride-containing product, including dutasteride and tamsulosin hydrochloride capsules, to patients taking potent, chronic CYP3A4 enzyme inhibitors (e.g., ritonavir) [see Clinical Pharmacology ( 12.3 ) ] . Tamsulosin Strong and Moderate Inhibitors of CYP3A4 or CYP2D6: Tamsulosin is extensively metabolized, mainly by CYP3A4 or CYP2D6.

Mechanism: Taking both of these means you are taking the same medicine twice, which can cause your blood pressure to drop too low or cause other side effects.

What to do: Do not take extra tamsulosin if your combination pill already contains it.

7.2 Warfarin Dutasteride Concomitant administration of dutasteride 0.5 mg/day for 3 weeks with warfarin does not alter the steady-state pharmacokinetics of the S- or R-warfarin isomers or alter the effect of warfarin on prothrombin time [see Clinical Pharmacology ( 12.3 ) ] . Tamsulosin A definitive drug-drug interaction trial between tamsulosin hydrochloride and warfarin was not conducted. Caution should be exercised with concomitant administration of warfarin and tamsulosin-containing products, including dutasteride and tamsulosin hydrochloride capsules [see Warnings and Precautions ( 5.2...

Mechanism: One part of this combination medicine has not been fully tested with blood thinners, so it is unclear how they might affect each other.

What to do: Use caution when taking these together and talk to your doctor about monitoring your blood closely.

Concomitant treatment with paroxetine (a strong inhibitor of CYP2D6) resulted in increases in the C max and area under the concentration-time curve (AUC) of tamsulosin by factors of 1.3 and 1.6, respectively.

Mechanism: Paroxetine stops an enzyme from breaking down tamsulosin, which causes the drug levels in your body to rise.

What to do: Your doctor may need to monitor you for side effects or change your dose.

7.3 Nifedipine, Atenolol, Enalapril Tamsulosin Dosage adjustments are not necessary when tamsulosin is administered concomitantly with nifedipine, atenolol, or enalapril [see Clinical Pharmacology ( 12.3 ) ] .

Mechanism: These medications do not significantly affect how the other drug is handled by the body.

What to do: No dose adjustments are necessary when taking these two drugs at the same time.