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Drug Interactions between carbamazepine and letermovir

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

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Interactions between your drugs

Moderate

carBAMazepine letermovir

Applies to: carbamazepine and letermovir

GENERALLY AVOID: Coadministration with inducers of the P-glycoprotein (P-gp) efflux transporter and/or the uridine diphosphate glucuronosyltransferase (UGT) enzymes may decrease the plasma concentrations of letermovir according to the product labeling. Because letermovir is a substrate of P-gp and UGT 1A1 and 1A3, induction of the efflux transporter and metabolic enzymes may theoretically increase the clearance of letermovir. Concomitant use of rifampin initially resulted in a clinically insignificant increase in letermovir plasma concentrations (due to inhibition of organic anion transporting polypeptide [OATP] 1B1/3 and/or P-gp), followed by clinically significant decreases in letermovir plasma concentrations with continued rifampin coadministration (due to induction of P-gp/UGT).

MANAGEMENT: Due to the potential loss of efficacy, use of letermovir with inducers of the P-glycoprotein (P-gp) efflux transporter and/or the uridine diphosphate glucuronosyltransferase (UGT) enzymes is not recommended.

References (4)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. Cerner Multum, Inc. "Australian Product Information."
  3. Cerner Multum, Inc. (2015) "Canadian Product Information."
  4. (2017) "Product Information. Prevymis (letermovir)." Merck & Co., Inc

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 (3)
  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

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.

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