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Drug Interactions between Agenerase and silodosin

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

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Interactions between your drugs

Major

amprenavir silodosin

Applies to: Agenerase (amprenavir) 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

amprenavir food

Applies to: Agenerase (amprenavir)

GENERALLY AVOID: Administration with a high-fat meal may decrease the oral bioavailability of amprenavir. The mechanism is unknown. In healthy volunteers, consumption of a standardized high-fat meal decreased the peak plasma concentration (Cmax) and area under the concentration-time curve (AUC) of amprenavir (1200 mg single oral dose) by 36% and 21%, respectively, compared to administration in the fasted state. The time to reach Cmax (Tmax) was increased 44% following a high-fat meal.

Grapefruit juice does not appear to significantly affect the pharmacokinetics of amprenavir. In 12 healthy volunteers, administration with grapefruit juice (200 mL) decreased the mean peak plasma concentration (Cmax) of amprenavir (1200 mg single oral dose) by 22% compared to water. The median time to reach Cmax (Tmax) was prolonged from 0.75 to 1.13 hours. These pharmacokinetic changes are not thought to be clinically significant, since antiretroviral response is more closely associated with systemic exposure (AUC) and trough plasma concentration (Cmin), which were not affected in the study.

MANAGEMENT: Amprenavir may be taken with or without food, but should not be taken with a high-fat meal.

References (2)
  1. (2001) "Product Information. Agenerase (amprenavir)." Glaxo Wellcome
  2. Demarles D, Gillotin C, Bonaventure-Paci S, Vincent I, Fosse S, Taburet AM (2002) "Single-dose pharmacokinetics of amprenavir coadministered with grapefruit juice." Antimicrob Agents Chemother, 46, p. 1589-1590
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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