Drug interactions
Fosphenytoin + Nimodipine
Severity: Major
Fosphenytoin and Nimodipine: 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
Phenytoin, the active metabolite of fosphenytoin, strongly induces CYP3A4 and can markedly reduce nimodipine concentrations. This may compromise its protective effect.
What this interaction means in plain words
Fosphenytoin and Nimodipine 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 belongs to Central Nervous System; Nimodipine belongs to Cardiovascular.
Why it happens
Phenytoin-mediated CYP3A4 induction increases nimodipine clearance.
What to do
Avoid the combination if possible, or monitor response closely and expect to need higher nimodipine doses. Watch for hypotension and reassess when fosphenytoin is stopped.
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 Nimodipine
- Apalutamide + Nimodipine Major
- Carbamazepine + Nimodipine Major
- Ceritinib + Nimodipine Major
- Clarithromycin + Nimodipine Major
- Cobicistat + Nimodipine Major
- Darunavir + Nimodipine Major
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 Nimodipine?
MediHelp rates the interaction as major. Fosphenytoin and Nimodipine 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. Phenytoin, the active metabolite of fosphenytoin, strongly induces CYP3A4 and can markedly reduce nimodipine concentrations. This may compromise its protective effect.
How serious is the interaction between Fosphenytoin and Nimodipine?
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, or monitor response closely and expect to need higher nimodipine doses. Watch for hypotension and reassess when fosphenytoin is stopped.
What other medicines interact with Nimodipine?
MediHelp also lists interactions of Nimodipine with, for example, Apalutamide, Carbamazepine, Ceritinib. The full list is on the Nimodipine page.
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