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Drug Interactions between carbamazepine and vemurafenib

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

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Interactions between your drugs

Major

carBAMazepine vemurafenib

Applies to: carbamazepine and vemurafenib

GENERALLY AVOID: Coadministration with potent inducers of CYP450 3A4 may decrease the plasma concentrations of vemurafenib, which has been shown in vitro to be a substrate of the isoenzyme. According to the product labeling, administration of a single 960 mg dose of vemurafenib with the potent CYP450 3A4 inducer rifampin at a dosage of 600 mg once daily resulted in a 40% decrease in vemurafenib systemic exposure (AUC) relative to vemurafenib administered alone, with no effect on peak plasma concentration (Cmax). Reduced therapeutic efficacy of vemurafenib may occur.

MANAGEMENT: Concomitant use of vemurafenib with potent CYP450 3A4 inducers should generally be avoided. Alternative therapeutic agents with less enzyme induction potential should be considered whenever possible during treatment with vemurafenib. If coadministration is required, the manufacturer recommends increasing the dose of vemurafenib by 240 mg (one tablet) as tolerated. Close monitoring for toxicities (e.g., QT prolongation, hepatotoxicity, nephrotoxicity, photosensitivity, dermatologic reactions, uveitis) is advised following dose increase. Two weeks after discontinuation of the strong CYP450 3A4 inducer, the vemurafenib dose that was taken prior to initiating the inducer may be resumed.

References

  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."
  3. (2011) "Product Information. Zelboraf (vemurafenib)." Genentech

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Drug and food interactions

Moderate

carBAMazepine food

Applies to: carbamazepine

GENERALLY AVOID: Alcohol may potentiate some of the pharmacologic effects of carbamazepine. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

In a small, randomized, crossover study, the administration of carbamazepine with grapefruit juice (compared to water) increased plasma drug concentrations by approximately 40%. The proposed mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits.

MANAGEMENT: Patients receiving carbamazepine should be advised to avoid or limit consumption of alcohol. Given the drug's narrow therapeutic index, patients receiving carbamazepine therapy should preferably avoid the regular consumption of grapefruits and grapefruit juice to prevent any undue fluctuations in plasma drug levels. Patients should be advised to report signs of carbamazepine toxicity (nausea, visual disturbances, dizziness, or ataxia) to their physicians.

References

  1. (2002) "Product Information. Tegretol (carbamazepine)." Novartis Pharmaceuticals
  2. Garg SK, Kumar N, Bhargava VK, Prabhakar SK (1998) "Effect of grapefruit juice on carbamazepine bioavailability in patients with epilepsy." Clin Pharmacol Ther, 64, p. 286-8
  3. Bailey DG, Dresser GR, Kreeft JH, Munoz C, Freeman DJ, Bend JR (2000) "Grapefruit-felodipine interaction: Effect of unprocessed fruit and probable active ingredients." Clin Pharmacol Ther, 68, p. 468-77

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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.


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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.