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Drug Interactions between alfuzosin and nirmatrelvir / ritonavir

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

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Interactions between your drugs

Major

ritonavir alfuzosin

Applies to: nirmatrelvir / ritonavir and alfuzosin

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of alfuzosin, which is primarily metabolized by the isoenzyme. Severe hypotension and priapism may occur. In pharmacokinetic studies, repeated oral administration of 400 mg/day of ketoconazole, a potent CYP450 3A4 inhibitor, increased alfuzosin peak plasma concentration (Cmax) and systemic exposure (AUC) by 2.3- and 3.2-fold, respectively, following a single 10 mg dose. Repeated oral administration of ketoconazole 200 mg/day increased alfuzosin Cmax by 2.1-fold and AUC by 2.5-fold following a single 10 mg dose.

MANAGEMENT: Concomitant use of alfuzosin with potent CYP450 3A4 inhibitors such as itraconazole, ketoconazole, posaconazole, voriconazole, conivaptan, nefazodone, cobicistat, delavirdine, protease inhibitors, and ketolide and certain macrolide antibiotics is considered contraindicated. Some authorities recommend avoiding concomitant use of alfuzosin during and for 2 weeks after treatment with itraconazole.

References (5)
  1. (2002) "Product Information. Sporanox (itraconazole)." Janssen Pharmaceuticals
  2. (2003) "Product Information. Uroxatral (alfuzosin)." sanofi-aventis
  3. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  4. EMEA. European Medicines Agency (2007) EPARs. European Union Public Assessment Reports. http://www.ema.europa.eu/ema/index.jsp?curl=pages/includes/medicines/medicines_landingpage.jsp&mid
  5. Cerner Multum, Inc. "Australian Product Information."

Drug and food interactions

Moderate

ritonavir food

Applies to: nirmatrelvir / ritonavir

ADJUST DOSING INTERVAL: Administration with food may modestly affect the bioavailability of ritonavir from the various available formulations. When the oral solution was given under nonfasting conditions, peak ritonavir concentrations decreased 23% and the extent of absorption decreased 7% relative to fasting conditions. Dilution of the oral solution (within one hour of dosing) with 240 mL of chocolate milk or a nutritional supplement (Advera or Ensure) did not significantly affect the extent and rate of ritonavir absorption. When a single 100 mg dose of the tablet was administered with a high-fat meal (907 kcal; 52% fat, 15% protein, 33% carbohydrates), approximately 20% decreases in mean peak concentration (Cmax) and systemic exposure (AUC) were observed relative to administration after fasting. Similar decreases in Cmax and AUC were reported when the tablet was administered with a moderate-fat meal. In contrast, the extent of absorption of ritonavir from the soft gelatin capsule formulation was 13% higher when administered with a meal (615 KCal; 14.5% fat, 9% protein, and 76% carbohydrate) relative to fasting.

MANAGEMENT: Ritonavir should be taken with meals to enhance gastrointestinal tolerability.

References (1)
  1. (2001) "Product Information. Norvir (ritonavir)." Abbott Pharmaceutical
Moderate

alfuzosin food

Applies to: alfuzosin

ADJUST DOSING INTERVAL: Administration of alfuzosin with food enhances oral bioavailability. According to the manufacturer, extent of absorption is 50% higher when administered under fed conditions compared to fasting conditions.

MANAGEMENT: To ensure maximal oral absorption, alfuzosin should be administered with or immediately after a meal.

References (1)
  1. (2003) "Product Information. Uroxatral (alfuzosin)." sanofi-aventis

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

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