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Drug Interactions between belzutifan and dutasteride / tamsulosin

This report displays the potential drug interactions for the following 2 drugs:

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Interactions between your drugs

Moderate

tamsulosin belzutifan

Applies to: dutasteride / tamsulosin and belzutifan

MONITOR: Coadministration with belzutifan may decrease the plasma concentrations and therapeutic effects of drugs that are substrates of CYP450 3A4. The extent of the decrease in concentration and effects may be more pronounced in patients who are dual uridine diphosphate glucuronosyltransferase (UGT) 2B17 and CYP450 2C19 poor metabolizers. The proposed mechanism is increased clearance due to belzutifan-mediated induction of CYP450 3A4. Concomitant use of belzutifan (120 mg once daily) with midazolam (a sensitive CYP450 3A4 substrate) decreased the midazolam systemic exposure (AUC) and peak plasma concentration (Cmax) by 40% and 34%, respectively. In patients with higher belzutifan concentrations (e.g., dual UGT 2B17 and CYP450 2C19 poor metabolizers) the AUC of midazolam is predicted to decrease by up to 70%.

MANAGEMENT: Caution is advised when belzutifan is used concomitantly with drugs that undergo metabolism by CYP450 3A4. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever belzutifan is added to or withdrawn from therapy. Patients should be monitored for diminished therapeutic effects.

References (1)
  1. (2021) "Product Information. Welireg (belzutifan)." Merck & Co., Inc
Moderate

dutasteride belzutifan

Applies to: dutasteride / tamsulosin and belzutifan

MONITOR: Coadministration with belzutifan may decrease the plasma concentrations and therapeutic effects of drugs that are substrates of CYP450 3A4. The extent of the decrease in concentration and effects may be more pronounced in patients who are dual uridine diphosphate glucuronosyltransferase (UGT) 2B17 and CYP450 2C19 poor metabolizers. The proposed mechanism is increased clearance due to belzutifan-mediated induction of CYP450 3A4. Concomitant use of belzutifan (120 mg once daily) with midazolam (a sensitive CYP450 3A4 substrate) decreased the midazolam systemic exposure (AUC) and peak plasma concentration (Cmax) by 40% and 34%, respectively. In patients with higher belzutifan concentrations (e.g., dual UGT 2B17 and CYP450 2C19 poor metabolizers) the AUC of midazolam is predicted to decrease by up to 70%.

MANAGEMENT: Caution is advised when belzutifan is used concomitantly with drugs that undergo metabolism by CYP450 3A4. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever belzutifan is added to or withdrawn from therapy. Patients should be monitored for diminished therapeutic effects.

References (1)
  1. (2021) "Product Information. Welireg (belzutifan)." Merck & Co., Inc

Drug and food interactions

Moderate

tamsulosin food

Applies to: dutasteride / tamsulosin

ADJUST DOSING INTERVAL: Food may delay the gastrointestinal absorption of tamsulosin. The time to maximum plasma concentration (Tmax) is reached by 4 to 5 hours under fasted conditions and by 6 to 7 hours when tamsulosin is administered with food. The delay in Tmax has the desirable effect of smoothing the tamsulosin plasma concentration profile, thereby reducing fluctuation of the plasma peak and trough concentrations with multiple dosing. Food may also affect the extent of absorption of tamsulosin. It has been reported that taking tamsulosin under fasted conditions results in a 30% increase in bioavailability (AUC) and 40% to 70% increase in peak plasma concentration (Cmax) compared to fed conditions. The effects of food on the pharmacokinetics of tamsulosin are consistent regardless of whether tamsulosin is taken with a light meal or a high-fat meal.

MANAGEMENT: To ensure uniformity of absorption, tamsulosin should be administered approximately one-half hour following the same meal each day.

References (1)
  1. (2001) "Product Information. Flomax (tamsulosin)." Boehringer-Ingelheim

Therapeutic duplication warnings

No warnings were found for your selected drugs.

Therapeutic duplication warnings are only returned when drugs within the same group exceed the recommended therapeutic duplication maximum.

See also

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Drug Interaction Classification

These classifications are only a guideline. The relevance of a particular drug interaction to a specific individual is difficult to determine. Always consult your healthcare provider before starting or stopping any medication.
Major Highly clinically significant. Avoid combinations; the risk of the interaction outweighs the benefit.
Moderate Moderately clinically significant. Usually avoid combinations; use it only under special circumstances.
Minor Minimally clinically significant. Minimize risk; assess risk and consider an alternative drug, take steps to circumvent the interaction risk and/or institute a monitoring plan.
Unknown No interaction information available.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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