Drug interactions
Dantrolene + Fosphenytoin
Severity: Moderate
Dantrolene and Fosphenytoin: 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, converted to phenytoin, induces CYP3A4 and may lower dantrolene concentrations, reducing its efficacy. The effect is predicted from the mechanism and has limited clinical documentation.
What this interaction means in plain words
Dantrolene and Fosphenytoin 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.
Dantrolene belongs to Musculoskeletal; Fosphenytoin belongs to Central Nervous System.
Why it happens
Phenytoin induction of CYP3A4 may increase dantrolene metabolism.
What to do
Monitor for reduced spasticity control or antimalignant hyperthermia efficacy and titrate dantrolene dose as needed. Also monitor liver function.
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 Dantrolene
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 Dantrolene with Fosphenytoin?
MediHelp rates the interaction as moderate. Dantrolene and Fosphenytoin 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, converted to phenytoin, induces CYP3A4 and may lower dantrolene concentrations, reducing its efficacy. The effect is predicted from the mechanism and has limited clinical documentation.
How serious is the interaction between Dantrolene and Fosphenytoin?
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 for reduced spasticity control or antimalignant hyperthermia efficacy and titrate dantrolene dose as needed. Also monitor liver function.
What other medicines interact with Dantrolene?
MediHelp also lists interactions of Dantrolene with, for example, Benzhydrocodone / acetaminophen, Buprenorphine long-acting, Buprenorphine subdermal implant. The full list is on the Dantrolene page.
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