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Drug Interactions between atazanavir and mibefradil

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

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Interactions between your drugs

Moderate

mibefradil atazanavir

Applies to: mibefradil and atazanavir

MONITOR: Coadministration with atazanavir may increase the plasma concentrations and pharmacologic effects of calcium channel blockers, especially the dihydropyridines (e.g., amlodipine, felodipine, nicardipine, nifedipine, nisoldipine). The mechanism involves atazanavir inhibition of intestinal and hepatic CYP450 3A4, the isoenzyme primarily responsible for the metabolic clearance of most calcium channel blockers. In a pharmacokinetic study, coadministration of atazanavir (400 mg once a day) and diltiazem (180 mg once a day) resulted in a 2-fold increase in diltiazem plasma concentration, and an additive prolonging effect on the PR interval was observed.

MANAGEMENT: Close monitoring of clinical response and tolerance is recommended if calcium channel blockers are used in combination with atazanavir. Dosage reduction may be required for the calcium channel blocker, particularly if it is a dihydropyridine. ECG monitoring may be appropriate due to potential additive effects on the PR interval. Patients should be advised to seek medical attention if they experience edema or swelling of the lower extremities; sudden, unexplained weight gain; difficulty breathing; chest pain or tightness; or hypotension as indicated by dizziness, fainting, or orthostasis.

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

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

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.