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Drug Interactions between halofantrine and primaquine

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

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Interactions between your drugs

Major

primaquine halofantrine

Applies to: primaquine and halofantrine

CONTRAINDICATED: Halofantrine can cause dose-related prolongation of the QT interval at recommended therapeutic doses. QTc interval prolongation and death have been reported during combination use of halofantrine and mefloquine. Theoretically, coadministration with other agents that can prolong the QT interval may result in additive effects and increased risk of ventricular arrhythmias including torsade de pointes and sudden death.

MANAGEMENT: Coadministration of halofantrine with other drugs that can prolong the QT interval is considered contraindicated. The manufacturer recommends performing an ECG before initiating halofantrine therapy and monitoring cardiac rhythm during and for 8 to 12 hours after completion of therapy.

References (9)
  1. (2021) "Product Information. Mefloquine Hydrochloride (mefloquine)." Hikma USA (formerly West-Ward Pharmaceutical Corporation)
  2. Giao PT, de Vries PJ (2001) "Pharmacokinetic interactions of antimalarial agents." Clin Pharmacokinet, 40, p. 343-73
  3. (2003) "Product Information. Halfan (halofantrine)." GlaxoSmithKline
  4. Nosten F, ter Kuile FO, Luxemburger C, et al. (1993) "Cardiac effects of antimalarial treatment with halofantrine." Lancet, 341, p. 1054-6
  5. (2001) "Sudden death in a traveler following halofantrine administration--Togo, 2000." MMWR Morb Mortal Wkly Rep, 50, 169-70, 179
  6. Abernethy DR, Wesche DL, Barbey JT, et al. (2001) "Stereoselective halofantrine disposition and effect: concentration-related QTc prolongation." Br J Clin Pharmacol, 51, p. 231-7
  7. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  8. Canadian Pharmacists Association (2006) e-CPS. http://www.pharmacists.ca/function/Subscriptions/ecps.cfm?link=eCPS_quikLink
  9. Cerner Multum, Inc. "Australian Product Information."

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

Therapeutic duplication warnings

Therapeutic duplication is the use of more than one medicine from the same drug category or therapeutic class to treat the same condition. This can be intentional in cases where drugs with similar actions are used together for demonstrated therapeutic benefit. It can also be unintentional in cases where a patient has been treated by more than one doctor, or had prescriptions filled at more than one pharmacy, and can have potentially adverse consequences.

Duplication

Antimalarials

Therapeutic duplication

The recommended maximum number of medicines in the 'antimalarials' category to be taken concurrently is usually one. Your list includes two medicines belonging to the 'antimalarials' category:

  • halofantrine
  • primaquine

Note: In certain circumstances, the benefits of taking this combination of drugs may outweigh any risks. Always consult your healthcare provider before making changes to your medications or dosage.

See also

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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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