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Drug Interactions between atazanavir and silodosin

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

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Interactions between your drugs

Major

atazanavir silodosin

Applies to: atazanavir and silodosin

CONTRAINDICATED: Coadministration with potent inhibitors of CYP450 3A4 may significantly increase the plasma concentrations of silodosin, which is primarily metabolized by the isoenzyme. Severe hypotension and priapism may occur. In pharmacokinetic studies, administration of a single 8 mg dose of silodosin with the potent CYP450 3A4 inhibitor ketoconazole 400 mg/day for 4 days resulted in a 3.8-fold increase in silodosin peak plasma concentration (Cmax) and 3.2-fold increase in systemic exposure (AUC). Coadministration of a single 4 mg dose of silodosin with ketoconazole 200 mg/day for 4 days resulted in 3.7- and 2.9-fold increases in silodosin Cmax and AUC, respectively.

MANAGEMENT: Concomitant use of silodosin with potent CYP450 3A4 inhibitors is considered contraindicated. Some authorities recommend avoiding concomitant use of silodosin during and for 2 weeks after treatment with itraconazole.

References (3)
  1. (2002) "Product Information. Sporanox (itraconazole)." Janssen Pharmaceuticals
  2. Cerner Multum, Inc. "Australian Product Information."
  3. (2008) "Product Information. Rapaflo (silodosin)." Watson Pharmaceuticals

Drug and food interactions

Moderate

atazanavir food

Applies to: atazanavir

ADJUST DOSING INTERVAL: Administration of atazanavir with food enhances oral bioavailability and reduces pharmacokinetic variability. According to the manufacturer, administration with a light meal increased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of a single 400 mg dose of atazanavir by 57% and 70%, respectively, relative to the fasting state. Administration with a high-fat meal resulted in a mean increase of 35% in atazanavir AUC and no change in Cmax compared to fasting. The coefficient of variation of AUC and Cmax decreased by approximately one-half when given with either a light or high-fat meal compared to the fasting state.

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

References (1)
  1. (2003) "Product Information. Reyataz (atazanavir)." Bristol-Myers Squibb
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.

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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