Drug interactions
Fosphenytoin + Pimozide
Severity: Moderate
Fosphenytoin and Pimozide: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Fosphenytoin, via its active metabolite phenytoin, induces CYP3A4 and may lower pimozide concentrations, potentially reducing efficacy. Pimozide also has seizure-threshold effects that matter in patients receiving anticonvulsants.
What this interaction means in plain words
Fosphenytoin and Pimozide can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Fosphenytoin belongs to Central Nervous System; Pimozide belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing pimozide metabolism.
What to do
Monitor tic control and consider ECG monitoring when adjusting pimozide. Re-check the dose if fosphenytoin or phenytoin is stopped.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Pimozide
- Adagrasib + Pimozide Contraindicated
- Amiodarone + Pimozide Contraindicated
- Amisulpride + Pimozide Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amoxapine + Pimozide Contraindicated
- Anagrelide + Pimozide Contraindicated
Other interactions of Fosphenytoin
- Dronedarone + Fosphenytoin Contraindicated
- Fosphenytoin + Ledipasvir-sofosbuvir Contraindicated
- Fosphenytoin + Lorlatinib Contraindicated
- Fosphenytoin + Lurasidone Contraindicated
- Fosphenytoin + Ranolazine Contraindicated
- Fosphenytoin + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
Frequently asked questions
Can I take Fosphenytoin with Pimozide?
MediHelp rates the interaction as moderate. Fosphenytoin and Pimozide can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fosphenytoin, via its active metabolite phenytoin, induces CYP3A4 and may lower pimozide concentrations, potentially reducing efficacy. Pimozide also has seizure-threshold effects that matter in patients receiving anticonvulsants.
How serious is the interaction between Fosphenytoin and Pimozide?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor tic control and consider ECG monitoring when adjusting pimozide. Re-check the dose if fosphenytoin or phenytoin is stopped.
What other medicines interact with Pimozide?
MediHelp also lists interactions of Pimozide with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Pimozide page.
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