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Drug Interactions between pimozide and thiabendazole

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

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Interactions between your drugs

Moderate

thiabendazole pimozide

Applies to: thiabendazole and pimozide

MONITOR: Coadministration with drugs that are inhibitors of CYP450 1A2 may increase the plasma concentrations of pimozide, which is partially metabolized by the isoenzyme. While clinical data are lacking, the possibility of prolonged and/or increased pharmacologic effects of pimozide, including serious adverse effects such as tardive dyskinesia, neuroleptic malignant syndrome and QT interval prolongation, should be considered in patients receiving concomitant CYP450 1A2 inhibitors.

MANAGEMENT: Because excessive prolongation of the QT interval is associated with an increased risk of ventricular arrhythmias such as ventricular tachycardia and torsades de pointes, an ECG should be performed prior to initiating therapy with pimozide and periodically thereafter, especially during dosage adjustment or following the addition of a CYP450 1A2 inhibitor.

References

  1. "Product Information. Orap (pimozide)." Gate Pharmaceuticals
  2. Krahenbuhl S, Sauter B, Kupferschmidt H, Krause M, Wyss PA, Meier PJ (1995) "Case report: reversible QT prolongation with torsades de pointes in a patient with pimozide intoxication." Am J Med Sci, 309, p. 315-6

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Drug and food interactions

Major

pimozide food

Applies to: pimozide

GENERALLY AVOID: Theoretically, the coadministration with grapefruit juice may increase the plasma concentrations of pimozide. The mechanism is decreased clearance of pimozide due to inhibition of CYP450 3A4-mediated first-pass metabolism in the gut wall by certain compounds present in grapefruits. The use of pimozide alone has been associated with dose-dependent prolongation of the QT interval. Although clinical data are lacking, this interaction may result in potentiation of the proarrhythmic effect of pimozide and consequently an increased risk of ventricular arrhythmias such as ventricular tachycardia and torsade de pointes. In addition, alcohol may potentiate some of the pharmacologic effects of pimozide. Use in combination may result in additive central nervous system depression and/or impairment of judgment, thinking, and psychomotor skills.

MANAGEMENT: The manufacturer recommends avoiding grapefruit juice (and probably grapefruits) during therapy with pimozide. Patients should also be advised to avoid or limit consumption of alcohol.

References

  1. "Product Information. Orap (pimozide)." Gate Pharmaceuticals
  2. Dresser GK, Spence JD, Bailey DG (2000) "Pharmacokinetic-pharmacodynamic consequences and clinical relevance of cytochrome P450 3A4 inhibition." Clin Pharmacokinet, 38, p. 41-57

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Moderate

thiabendazole food

Applies to: thiabendazole

MONITOR: Coadministration with thiabendazole may increase the plasma concentrations of caffeine. The mechanism is thiabendazole inhibition of the CYP450 1A2 metabolism of caffeine. In ten healthy, nonsmoking volunteers, administration of a single 136.5 mg dose of caffeine in combination with a single 500 mg dose of thiabendazole resulted in a nearly 60% increase in the area under the plasma concentration-time curve (AUC) of caffeine compared to administration without thiabendazole. In addition, the half-life of caffeine was increased from 11.9 to 28.6 hours, and oral clearance was reduced by 67% during coadministration with thiabendazole. The formation of paraxanthine from caffeine, which is primarily mediated by CYP450 1A2, was almost completely abolished until after the thiabendazole was cleared from the system.

MANAGEMENT: Patients should be advised that pharmacologic effects of caffeine may be increased during coadministration with thiabendazole.

References

  1. Bapiro TE, Sayi J, Hasler JA, et al. (2005) "Artemisinin and thiabendazole are potent inhibitors of cytochrome P450 1A2 (CYP1A2) activity in humans." Eur J Clin Pharmacol, 61, p. 755-61

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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.

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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