Drug interactions
Nisoldipine + Phenytoin
Severity: Major
Nisoldipine and Phenytoin: major 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
Phenytoin strongly induces CYP3A4, which markedly lowers nisoldipine bioavailability. Nisoldipine labeling advises against use with strong inducers because blood pressure or angina control may be lost.
What this interaction means in plain words
Nisoldipine and Phenytoin 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.
Nisoldipine belongs to Cardiovascular; Phenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induction of intestinal and hepatic CYP3A4 increases first-pass metabolism of nisoldipine.
What to do
Avoid the combination and choose another antihypertensive that is not CYP3A4-dependent. If it cannot be avoided, monitor blood pressure closely.
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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Other interactions of Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Other interactions of Nisoldipine
- Itraconazole + Nisoldipine Contraindicated
- Ketoconazole + Nisoldipine Contraindicated
- Apalutamide + Nisoldipine Major
- Carbamazepine + Nisoldipine Major
- Chloramphenicol + Nisoldipine Major
- Clarithromycin + Nisoldipine Major
Frequently asked questions
Can I take Nisoldipine with Phenytoin?
MediHelp rates the interaction as major. Nisoldipine and Phenytoin 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 strongly induces CYP3A4, which markedly lowers nisoldipine bioavailability. Nisoldipine labeling advises against use with strong inducers because blood pressure or angina control may be lost.
How serious is the interaction between Nisoldipine and Phenytoin?
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 and choose another antihypertensive that is not CYP3A4-dependent. If it cannot be avoided, monitor blood pressure closely.
What other medicines interact with Phenytoin?
MediHelp also lists interactions of Phenytoin with, for example, Artemether / lumefantrine, Bictegravir, Cabotegravir. The full list is on the Phenytoin page.
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