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Drug Interactions between atazanavir / cobicistat and Ketek

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

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Interactions between your drugs

Moderate

atazanavir telithromycin

Applies to: atazanavir / cobicistat and Ketek (telithromycin)

MONITOR: Coadministration with telithromycin may increase the plasma concentrations of drugs that are substrates of the CYP450 3A4 isoenzyme. The mechanism is decreased clearance due to inhibition of CYP450 3A4 activity by telithromycin.

MANAGEMENT: Caution is advised if telithromycin must be used concurrently with medications that undergo metabolism by CYP450 3A4, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever telithromycin is added to or withdrawn from therapy.

References

  1. (2004) "Product Information. Ketek (telithromycin)." Aventis Pharmaceuticals
  2. European Agency for the Evaluation of Medicinal Products. Committee for Proprietary Medicinal Products (2004) European Public Assessment Report Ketek (telithromycin) (Rev. 2) http:www.emea.eu.int/humandocs/Humans/EPAR/Ketek/Ketek.htm

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Moderate

telithromycin cobicistat

Applies to: Ketek (telithromycin) and atazanavir / cobicistat

MONITOR: Coadministration of a macrolide or ketolide antibiotic (clarithromycin, erythromycin, telithromycin) with cobicistat is expected to increase the plasma concentrations of both drugs. The mechanism may involve both competitive and noncompetitive inhibition of CYP450 3A4, since these drugs are all substrates as well as inhibitors of the isoenzyme. No pharmacokinetic data are currently available. Clinically, high plasma levels of macrolide or ketolide antibiotics may increase the risk of QT interval prolongation and torsade de pointes arrhythmia.

MANAGEMENT: Caution and close clinical monitoring are recommended if clarithromycin, erythromycin, or telithromycin are used in combination with cobicistat. Patients should be advised to seek medical attention if they experience symptoms that could indicate the occurrence of torsade de pointes such as dizziness, lightheadedness, fainting, palpitations, irregular heartbeat, shortness of breath, or syncope. Some authorities recommend avoiding the concomitant use of fixed combination antiretroviral products containing cobicistat with these antibiotics. For clarithromycin, a dosage reduction by 50% has been recommended in patients with CrCl between 30 and 60 mL/min. Data are not available in patients with CrCl less than 30 mL/min. However, in patients receiving atazanavir or ritonavir concomitantly with clarithromycin, it has been suggested that the dose of clarithromycin be reduced by 75% in patients with a CrCl of less than 30 mL/min. A similar dosage reduction may be appropriate when clarithromycin is used with cobicistat.

References

  1. (2001) "Product Information. Biaxin (clarithromycin)." Abbott Pharmaceutical
  2. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  3. Cerner Multum, Inc. "Australian Product Information."
  4. (2012) "Product Information. Stribild (cobicistat/elvitegravir/emtricitabine/tenofov)." Gilead Sciences
View all 4 references

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Drug and food interactions

Moderate

atazanavir food

Applies to: atazanavir / cobicistat

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

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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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