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Drug Interactions between fostamatinib and pimozide

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

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Interactions between your drugs

Moderate

pimozide fostamatinib

Applies to: pimozide and fostamatinib

MONITOR: Coadministration with fostamatinib may increase the plasma concentrations of drugs that are substrates of the CYP450 3A4 isoenzyme and/or P-glycoprotein (P-gp) transporter. The proposed mechanism is decreased clearance in the intestine and/or liver due to inhibition of CYP450 3A4-mediated metabolism and P-gp-mediated efflux by fostamatinib. According to the product labeling, administration of a single 40 mg dose of the CYP450 3A4 substrate simvastatin with fostamatinib 100 mg twice daily increased simvastatin peak plasma concentration (Cmax) and systemic exposure (AUC) by 113% and 64%, respectively. In addition, simvastatin acid Cmax increased by 83% and AUC increased by 64%. When the P-gp substrate digoxin (0.25 mg once daily) was administered with fostamatinib (100 mg twice daily), digoxin Cmax and AUC increased by 70% and 37%, respectively.

MANAGEMENT: Caution is advised when fostamatinib is used concurrently with drugs that are known substrates of CYP450 3A4 and/or P-gp, particularly those with a narrow therapeutic range. Dosage adjustments as well as clinical and laboratory monitoring may be appropriate for some drugs whenever fostamatinib is added to or withdrawn from therapy.

References (1)
  1. (2018) "Product Information. Tavalisse (fostamatinib)." Rigel Pharmaceuticals

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 (2)
  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

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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