Drug interactions
Cariprazine + Fosphenytoin
Severity: Major
Cariprazine and Fosphenytoin: major interaction.
Last updated Sources: US FDA label
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 is converted to phenytoin, a CYP3A4 inducer that may reduce concentrations of cariprazine and its active metabolites. This could lead to loss of antipsychotic efficacy.
What this interaction means in plain words
Cariprazine and Fosphenytoin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Cariprazine belongs to Central Nervous System; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induces CYP3A4, increasing clearance of cariprazine and its active metabolites.
What to do
Avoid the combination if possible, as labeling advises against strong CYP3A4 inducers. If used, monitor for relapse and adjust the cariprazine dose.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Cariprazine
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 Cariprazine with Fosphenytoin?
MediHelp rates the interaction as major. Cariprazine and Fosphenytoin can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Fosphenytoin is converted to phenytoin, a CYP3A4 inducer that may reduce concentrations of cariprazine and its active metabolites. This could lead to loss of antipsychotic efficacy.
How serious is the interaction between Cariprazine and Fosphenytoin?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination if possible, as labeling advises against strong CYP3A4 inducers. If used, monitor for relapse and adjust the cariprazine dose.
What other medicines interact with Cariprazine?
MediHelp also lists interactions of Cariprazine with, for example, Alfentanil, Amisulpride, Amobarbital. The full list is on the Cariprazine page.
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