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Drug Interactions between Aricept and halofantrine

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

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Interactions between your drugs

Minor

donepezil halofantrine

Applies to: Aricept (donepezil) and halofantrine

Coadministration with inhibitors of CYP450 2D6 and/or 3A4 may increase the plasma concentrations of donepezil, which is primarily metabolized by these isoenzymes. In a 7-day crossover study in 18 healthy volunteers, the potent CYP450 3A4 inhibitor ketoconazole (200 mg once daily) increased the mean peak plasma concentration (Cmax) and systemic exposure (AUC) of donepezil (5 mg once daily) by approximately 36% each. The clinical relevance of these increases is unknown. A prolonged duration of monitoring for adverse effects may be required depending on the elimination half-life of the concomitant drug. For example, it should be noted that rolapitant, a moderate CYP450 2D6 inhibitor, can increase plasma concentrations and the risk of adverse effects of donepezil for at least 28 days after administration of rolapitant.

References

  1. "Product Information. Aricept (donepezil)." Pfizer U.S. Pharmaceuticals PROD (2001):
  2. Tiseo PJ, Perdomo CA, Friedhoff LT "Concurrent administration of donepezil HCl and ketoconazole: assessment of pharmacokinetic changes following single and multiple doses." Br J Clin Pharmacol 46 (1998): 30-4
  3. Rojas-Fernandez C, Fisher C "Drug interactions and donepezil." J Am Geriat Soc 40 (2000): 597-8
  4. "Product Information. Varubi (rolapitant)." Tesaro Inc. (2015):
View all 4 references

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Drug and food interactions

Major

halofantrine food

Applies to: halofantrine

GENERALLY AVOID: Grapefruit juice may increase the plasma concentration of halofantrine. The mechanism is inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. After administration of 500 mg with 250 mL regular-strength grapefruit juice daily for 3 days, average halofantrine AUC increased 2.8-fold and peak plasma concentrations increased 3.2-fold, compared to water, in healthy subjects (n=12). QT interval prolongation increased from an average of 17 ms with water to 31 ms with grapefruit juice. Halofantrine, even at recommended doses, can cause dose-related prolongation of the QT interval, resulting in an elevated risk of potentially fatal ventricular arrhythmias including ventricular tachycardia and torsade de pointes.

ADJUST DOSING INTERVAL: The presence of food may increase the absorption and toxicity of halofantrine. Peak plasma concentrations increased seven-fold and AUC increased three-fold in healthy subjects when halofantrine was administered with high-fat food.

MANAGEMENT: The authors of the study recommend that grapefruit juice be avoided during halofantrine therapy. The manufacturer recommends performing an ECG before initiating halofantrine therapy and cardiac monitoring during and for 8 to 12 hours after completion of therapy. Halofantrine should be taken on an empty stomach at least 1 hour before or 2 hours after food.

References

  1. Giao PT, de Vries PJ "Pharmacokinetic interactions of antimalarial agents." Clin Pharmacokinet 40 (2001): 343-73
  2. "Product Information. Halfan (halofantrine)." GlaxoSmithKline (2003):
  3. Charbit B, Becquemont L, Lepere B, Peytavin G, Funck-Bretano C "Pharmacokinetic and pharmacodynamic interaction between grapefruit juice and halofantrine." Clin Pharmacol Ther 72 (2002): 514-23
  4. Abernethy DR, Wesche DL, Barbey JT, et al. "Stereoselective halofantrine disposition and effect: concentration-related QTc prolongation." Br J Clin Pharmacol 51 (2001): 231-7
View all 4 references

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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.

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