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Drug Interactions between fosamprenavir and tucatinib

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

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Interactions between your drugs

Moderate

fosamprenavir tucatinib

Applies to: fosamprenavir and tucatinib

MONITOR: Coadministration with tucatinib may increase the plasma concentrations of CYP450 3A4 substrates. The mechanism involves tucatinib-mediated inhibition of CYP450 3A isoenzymes. When a single 2 mg dose of midazolam, a CYP450 3A substrate, was administered with tucatinib (300 mg twice daily), midazolam peak plasma concentration (Cmax) and systemic exposure (AUC) increased by 3-fold and 5.7-fold, respectively. Increased exposure to the CYP450 3A substrate may increase the risk of toxicity.

MANAGEMENT: Caution is advised when tucatinib is used concomitantly with drugs that undergo metabolism by CYP450 3A4. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever tucatinib is added to or withdrawn from therapy.

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

Drug and food interactions

Moderate

fosamprenavir food

Applies to: fosamprenavir

ADJUST DOSING INTERVAL: Food may reduce the systemic bioavailability of amprenavir from fosamprenavir oral suspension. The mechanism of interaction has not been described. According to the product labeling, administration of fosamprenavir oral suspension (1400 mg single dose) with a high-fat meal (967 kcal, 67 g fat, 33 g protein, 58 g carbohydrate) reduced amprenavir peak plasma concentration (Cmax) by 46% and systemic exposure (AUC) by 28% compared to administration in a fasted state. The time to reach peak plasma level (Tmax) was delayed by 0.72 hours. In contrast, the same high-fat meal did not affect the pharmacokinetics of amprenavir from fosamprenavir tablets.

MANAGEMENT: Fosamprenavir suspension should be administered on an empty stomach in adults, but with food in pediatric patients to aid palatability and compliance. If emesis occurs within 30 minutes after dosing the suspension, the dose should be repeated. Fosamprenavir tablets may be taken with or without food.

References (1)
  1. (2003) "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline

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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