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Drug Interactions between Rifadin and silodosin

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

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Interactions between your drugs

Moderate

rifAMPin silodosin

Applies to: Rifadin (rifampin) and silodosin

MONITOR: Coadministration with inducers of CYP450 3A4 and/or P-glycoprotein (P-gp) may decrease the plasma concentrations of silodosin, which is a substrate of both the isoenzyme and efflux transporter.

MANAGEMENT: The potential for diminished pharmacologic effects of silodosin should be considered during coadministration with CYP450 3A4 and/or P-gp inducers. Alternative treatments may be required if an interaction is suspected.

References (3)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."
  3. (2008) "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals

Drug and food interactions

Moderate

rifAMPin food

Applies to: Rifadin (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.
Moderate

silodosin food

Applies to: silodosin

ADJUST DOSING INTERVAL: Food may reduce the oral bioavailability of silodosin. The effect of a moderate-fat, moderate-calorie meal on silodosin pharmacokinetics was variable and decreased silodosin maximum plasma concentration (Cmax) by approximately 18% to 43% and systemic exposure (AUC) by 4% to 49% across three different studies. The maximum effect of food (i.e., coadministration with a high-fat, high-calorie meal) on the pharmacokinetics of silodosin was not evaluated. Safety and efficacy clinical trials for silodosin were always conducted in the presence of food intake.

MANAGEMENT: Patients should be instructed to take silodosin with a meal to reduce the risk of adverse events.

References (1)
  1. (2008) "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals

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.


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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.