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Drug Interactions between exemestane and rifampin

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

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Interactions between your drugs

Moderate

rifAMPin exemestane

Applies to: rifampin and exemestane

ADJUST DOSE: Coadministration with potent inducers of CYP450 3A4 may significantly decrease the plasma concentrations of exemestane, which is primarily metabolized by the isoenzyme. In 10 healthy postmenopausal volunteers, administration of exemestane (25 mg single dose) following pretreatment with the potent inducer rifampin (600 mg daily for 14 days) resulted in a 41% decrease in exemestane peak plasma concentration (Cmax) and a 54% decrease in exemestane systemic exposure (AUC).

MANAGEMENT: The manufacturer recommends increasing the dosage of exemestane to 50 mg once daily when used with potent CYP450 3A4 inducers such as carbamazepine, enzalutamide, lumacaftor, mitotane, phenobarbital, phenytoin, primidone (partially metabolized to phenobarbital), rifamycins, and St. John's wort. However, it has also been suggested that suppression of estrogen levels is not affected by the interaction, thus dosage adjustment of exemestane is not required. The extent to which other, less potent CYP450 3A4 inducers may interact with exemestane is unknown. Caution is advised if they are used with exemestane.

References (1)
  1. (2001) "Product Information. Aromasin (exemestane)." Pharmacia and Upjohn

Drug and food interactions

Moderate

rifAMPin food

Applies to: rifampin

GENERALLY AVOID: Concurrent use of rifampin in patients who ingest alcohol daily may result in an increased incidence of hepatotoxicity. The increase in hepatotoxicity may be due to an additive risk as both alcohol and rifampin are individually associated with this adverse reaction. However, the exact mechanism has not been established.

ADJUST DOSING INTERVAL: Administration with food may reduce oral rifampin absorption, increasing the risk of therapeutic failure or resistance. In a randomized, four-period crossover phase I study of 14 healthy male and female volunteers, the pharmacokinetics of single dose rifampin 600 mg were evaluated under fasting conditions and with a high-fat meal. Researchers observed that administration of rifampin with a high-fat meal reduced rifampin peak plasma concentration (Cmax) by 36%, nearly doubled the time to reach peak plasma concentration (Tmax) but reduced overall exposure (AUC) by only 6%.

MANAGEMENT: The manufacturer of oral forms of rifampin recommends administration on an empty stomach, 30 minutes before or 2 hours after meals. Patients should be encouraged to avoid alcohol or strictly limit their intake. Patients who use alcohol and rifampin concurrently or have a history of alcohol use disorder may require additional monitoring of their liver function during treatment with rifampin.

References (6)
  1. (2022) "Product Information. Rifampin (rifAMPin)." Akorn Inc
  2. (2022) "Product Information. Rifampicin (rifampicin)." Mylan Pharmaceuticals Inc
  3. (2023) "Product Information. Rifadin (rifampicin)." Sanofi
  4. (2024) "Product Information. Rifadin (rifaMPICin)." Sanofi-Aventis Australia Pty Ltd
  5. Peloquin CA, Namdar R, Singleton MD, Nix DE (2024) Pharmacokinetics of rifampin under fasting conditions, with food, and with antacids https://pubmed.ncbi.nlm.nih.gov/9925057/
  6. (2019) "Product Information. Rofact (rifampin)." Bausch Health, Canada Inc.

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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