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Drug Interactions between fosaprepitant and Telzir

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

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Interactions between your drugs

Moderate

fosamprenavir fosaprepitant

Applies to: Telzir (fosamprenavir) and fosaprepitant

MONITOR: Coadministration with inhibitors of CYP450 3A4 may increase the plasma concentrations of aprepitant, which is primarily metabolized by the isoenzyme. According to the manufacturer, administration of a single 125 mg dose of aprepitant on day 5 of treatment with the potent CYP450 3A4 inhibitor ketoconazole (400 mg/day for 10 days) resulted in a 5-fold increase in mean aprepitant systemic exposure (AUC) and a 3-fold increase in mean terminal half-life. In patients with mild to moderate hypertension, coadministration of aprepitant (approximately 230 mg once a day) and the moderate inhibitor diltiazem (120 mg three times a day for 5 days) resulted in a 2-fold increase in the AUC of aprepitant and a 1.7-fold increase in that of diltiazem. No clinically significant changes in ECG, heart rate, or blood pressure were observed beyond those induced by diltiazem alone.

MANAGEMENT: Caution is advised if aprepitant is prescribed in combination with CYP450 3A4 inhibitors, particularly potent ones like itraconazole, ketoconazole, posaconazole, voriconazole, clarithromycin, conivaptan, idelalisib, nefazodone, telithromycin, cobicistat, delavirdine, and protease inhibitors. Pharmacologic response to aprepitant should be monitored more closely whenever a CYP450 3A4 inhibitor is added to or withdrawn from therapy. In addition, many CYP450 3A4 inhibitors are also substrates of the isoenzyme, thus pharmacologic response to these agents should also be monitored during coadministration with aprepitant.

References

  1. (2003) "Product Information. Emend (aprepitant)." Merck & Co., Inc
  2. (2008) "Product Information. Emend for Injection (fosaprepitant)." Merck & Co., Inc

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Drug and food interactions

Moderate

fosamprenavir food

Applies to: Telzir (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. (2003) "Product Information. Lexiva (fosamprenavir)." GlaxoSmithKline

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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.