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Drug Interactions between boceprevir and doxazosin

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

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Interactions between your drugs

Major

doxazosin boceprevir

Applies to: doxazosin and boceprevir

CONTRAINDICATED: Coadministration with boceprevir, a potent inhibitor of CYP450 3A4, may significantly increase the plasma concentrations of alpha 1-adrenergic blockers that are primarily metabolized by the isoenzyme. Severe hypotension and priapism may occur. Although the interaction has not been specifically studied with boceprevir, other potent CYP450 3A4 inhibitors like ketoconazole have been shown to increase the systemic exposure (AUC) to alfuzosin, silodosin and tamsulosin by approximately 3-fold. In one case report, a 44-year-old man with multiple comorbidities including HIV and HCV developed priapism nine days following the initiation of boceprevir. Among the multitude of drugs the patient was receiving, an interaction between boceprevir and doxazosin, tamsulosin, and/or quetiapine resulting in excessive alpha-1 adrenergic blockade was thought to be the probable cause. The patient required a surgically performed distal penile shunt to correct the problem.

MANAGEMENT: Concomitant use of boceprevir with alfuzosin, doxazosin, silodosin, or tamsulosin is considered contraindicated.

References (2)
  1. Cerner Multum, Inc. "Australian Product Information."
  2. (2011) "Product Information. Victrelis (boceprevir)." Schering-Plough Corporation

Drug and food interactions

Moderate

boceprevir food

Applies to: boceprevir

ADJUST DOSING INTERVAL: Food significantly enhances the oral bioavailability of boceprevir. When given at 800 mg three times daily with food, boceprevir exposure increased by up to 65% relative to administration in the fasting state. The bioavailability of boceprevir was similar regardless of meal type (e.g., high-fat versus low-fat) or whether taken 5 minutes prior to eating, during a meal, or immediately following completion of the meal. Therefore, boceprevir may be taken without regard to either meal type or timing of the meal.

MANAGEMENT: To ensure maximal oral absorption, boceprevir should be administered with a meal or light snack.

References (1)
  1. (2011) "Product Information. Victrelis (boceprevir)." Schering-Plough Corporation
Moderate

doxazosin food

Applies to: doxazosin

GENERALLY AVOID: The concurrent use of ethanol and alpha-1 adrenergic blockers may cause increased hypotensive effects. Patients with aldehyde dehydrogenase deficiencies (primarily Asians) may be at a higher risk of this interaction. The mechanism has not been determined. Data exist for prazosin and other alpha adrenergic blockers are expected to interact also. In addition, any patients taking alpha adrenergic blockers may experience excessive orthostatic hypotension with ethanol ingestion, due to ethanol's unopposed vasodilatory effects in the presence of alpha adrenergic blockade.

MANAGEMENT: Patients who develop a flushing reaction after ethanol ingestion (indicates a possible aldehyde dehydrogenase deficiency) should be advised to avoid ethanol or limit their intake. All patients should be warned about the possibility of orthostatic hypotension with concurrent ethanol use.

References (2)
  1. Kawano Y, Abe H, Kojima S, Takishita S, Omae T (2000) "Interaction of alcohol and an a1-blocker on ambulatory blood pressure in patients with essential hypertension." Am J Hypertens, 13, p. 307-12
  2. (2002) "Product Information. Xatral (alfuzosin)." Sanofi-Synthelabo 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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