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Drug Interactions between amifampridine and pimozide

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

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Interactions between your drugs

Moderate

pimozide amifampridine

Applies to: pimozide and amifampridine

MONITOR: The use of amifampridine is associated with a dose-related risk of seizures, and the risk may be further increased when coadministered with other drugs that can reduce the seizure threshold such as antidepressants, antimalarials, neuroleptics, phenothiazines, and quinolones. Seizures have occurred in patients without a history of seizures taking amifampridine at recommended dosages and at various times after initiation of treatment. Reported incidence is approximately 2%. Many of the patients were taking medications or had comorbid medical conditions that may have lowered the seizure threshold.

MANAGEMENT: Caution is advised if amifampridine is coadministered with any substance that can reduce the seizure threshold, particularly in the elderly and in patients with other risk factors for seizures (e.g., head trauma; brain tumor; severe hepatic cirrhosis; metabolic disorders; CNS infections; excessive use of alcohol or sedatives; addiction to opiates, cocaine, or stimulants; diabetes treated with oral hypoglycemic agents or insulin). Consider discontinuation or dose reduction of amifampridine in patients who experience a seizure during treatment. Use of amifampridine is contraindicated in patients with a history of seizures.

References (3)
  1. Cerner Multum, Inc. "UK Summary of Product Characteristics."
  2. EMEA. European Medicines Agency (2007) EPARs. European Union Public Assessment Reports. http://www.ema.europa.eu/ema/index.jsp?curl=pages/includes/medicines/medicines_landingpage.jsp&mid
  3. (2018) "Product Information. Firdapse (amifampridine)." Catalyst Pharmaceuticals, Inc.

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.

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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

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