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Drug Interactions between Digitek and tucatinib

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

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Interactions between your drugs

Moderate

digoxin tucatinib

Applies to: Digitek (digoxin) and tucatinib

MONITOR: Coadministration with tucatinib may increase the plasma concentrations of drugs that are substrates of the P-glycoprotein (P-gp) transporter. The mechanism likely involves tucatinib-mediated inhibition of P-gp. When a single 0.5 mg dose of digoxin, a P-gp substrate, was administered with tucatinib (300 mg twice daily), digoxin peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 2.4-fold and 1.5-fold, respectively. Increased exposure to the P-gp substrate may increase the risk of toxicity.

MANAGEMENT: Caution is advised if tucatinib is used concomitantly with P-gp substrates, particularly those with a narrow therapeutic index. A dose reduction of the P-gp substrates as well as clinical and laboratory monitoring may be appropriate.

References (1)
  1. (2020) "Product Information. Tukysa (tucatinib)." Seattle Genetics Inc

Drug and food interactions

Minor

digoxin food

Applies to: Digitek (digoxin)

Administration of digoxin with a high-fiber meal has been shown to decrease its bioavailability by almost 20%. Fiber can sequester up to 45% of the drug when given orally. Patients should be advised to maintain a regular diet without significant fluctuation in fiber intake while digoxin is being titrated.

Grapefruit juice may modestly increase the plasma concentrations of digoxin. The mechanism is increased absorption of digoxin due to mild inhibition of intestinal P-glycoprotein by certain compounds present in grapefruits. In 12 healthy volunteers, administration of grapefruit juice with and 30 minutes before, as well as 3.5, 7.5, and 11.5 hours after a single digoxin dose (0.5 mg) increased the mean area under the plasma concentration-time curve (AUC) of digoxin by just 9% compared to administration with water. Moreover, P-glycoprotein genetic polymorphism does not appear to influence the magnitude of the effects of grapefruit juice on digoxin. Thus, the interaction is unlikely to be of clinical significance.

References (2)
  1. Darcy PF (1995) "Nutrient-drug interactions." Adverse Drug React Toxicol Rev, 14, p. 233-54
  2. Becquemont L, Verstuyft C, Kerb R, et al. (2001) "Effect of grapefruit juice on digoxin pharmacokinetics in humans." Clin Pharmacol Ther, 70, p. 311-6

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.