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Drug Interactions between atazanavir and echinacea

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

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Interactions between your drugs

Moderate

echinacea atazanavir

Applies to: echinacea and atazanavir

MONITOR: Coadministration with echinacea may alter the plasma concentrations and therapeutic effects of drugs that are substrates of CYP450 3A4. Echinacea appears to inhibit intestinal CYP450 3A4, which would lead to an increase in oral midazolam (a sensitive 3A4 substrate) bioavailability; however, plasma levels of midazolam following oral administration do not appear to be affected by echinacea. In contrast, it appears that echinacea may also induce hepatic CYP450 3A4; thereby increasing the hepatic clearance of drugs that are substrates of CYP450 3A4. According to reports, echinacea may increase the hepatic clearance of intravenous (IV) midazolam by 34% and decrease the area under the concentration-time curve (AUC) and half-life of IV midazolam by 20% and 42%, respectively.

MANAGEMENT: In general, patients should be advised to consult their healthcare provider before using any herbal or alternative medicines. If echinacea is prescribed with a drug that is a CYP450 3A4 substrate, the possibility of an altered (increased or decreased) therapeutic response should be considered. Patients should be monitored more closely following the addition or withdrawal of echinacea and the dosage of the CYP450 3A4 substrate adjusted as necessary.

References (2)
  1. Gorski JC, Huang SM, Pinto A, et al. (2004) "The effect of echinacea (Echinacea purpurea root) on cytochrome P450 activity in vivo." Clin Pharmacol Ther, 75, p. 89-100
  2. Cerner Multum, Inc. "Australian Product Information."

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.