tamsulosin

7.7 Furosemide Tamsulosin hydrochloride capsules 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 tamsulosin hydrochloride capsules dosage [see Clinical Pharmacology (12.3)].

Mechanism: Furosemide slightly lowers the level of tamsulosin in your system, but the effect is too small to change how the medicine works.

What to do: You can take these medicines together safely without changing your dose.

Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). Concomitant treatment with paroxetine (a strong inhibitor of CYP2D6) resulted in an increase in the C max and AUC of tamsulosin by a factor of 1.3 and 1.6, respectively [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].

Mechanism: Paroxetine stops your body from breaking down tamsulosin normally, which leads to higher levels of the drug in your system. This can increase your risk of having side effects.

What to do: Use this combination with caution, especially if you are taking a higher dose of tamsulosin.

7.4 Warfarin A definitive drug-drug interaction study between tamsulosin hydrochloride and warfarin was not conducted. Caution should be exercised with concomitant administration of warfarin and tamsulosin hydrochloride capsules [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].

Mechanism: There is not enough research to know exactly how these drugs interact, but taking them together might change how your blood clots. This could make your treatment less safe.

What to do: Use caution when taking these drugs together and follow your doctor's advice for monitoring.

Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). The effects of concomitant administration of a moderate CYP3A4 inhibitor (e.g., erythromycin) on the pharmacokinetics of tamsulosin hydrochloride have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].

Mechanism: Erythromycin may slow down the way your body gets rid of tamsulosin, which could cause the drug to build up in your blood. This might lead to more side effects from the medicine.

What to do: Use this combination with caution, especially if your doctor has prescribed a higher dose of tamsulosin.

Tamsulosin hydrochloride capsules should be used with caution in combination with moderate inhibitors of CYP3A4 (e.g., erythromycin), in combination with strong (e.g., paroxetine) or moderate (e.g., terbinafine) inhibitors of CYP2D6, or in patients known to be CYP2D6 poor metabolizers, particularly at a dose higher than 0.4 mg (e.g., 0.8 mg). The effects of concomitant administration of a moderate CYP2D6 inhibitor (e.g., terbinafine) on the pharmacokinetics of tamsulosin hydrochloride have not been evaluated [see Warnings and Precautions (5.2) and Clinical Pharmacology (12.3)].

Mechanism: Terbinafine slows down the body's ability to break down tamsulosin by blocking a specific liver enzyme. This can lead to higher levels of tamsulosin in your blood.

What to do: Use this combination with caution. Your doctor may need to adjust your dose, especially if you are taking more than 0.4 mg of tamsulosin.