Drug interactions
Fosphenytoin + Secobarbital
Severity: Moderate
Fosphenytoin and Secobarbital: 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
Secobarbital may alter phenytoin concentrations after fosphenytoin conversion, usually lowering them, and adds sedative effects. Changes in phenytoin levels can lead to loss of seizure control or toxicity.
What this interaction means in plain words
Fosphenytoin and Secobarbital 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; Secobarbital belongs to Central Nervous System.
Why it happens
Barbiturate induction of CYP2C9/2C19 increases phenytoin metabolism; barbiturates can also compete variably for metabolism.
What to do
Monitor free and total phenytoin levels and seizure control when starting or stopping secobarbital. Adjust the fosphenytoin dose accordingly.
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 Secobarbital
- Calcium / magnesium / potassium / sodium oxybates + Secobarbital Contraindicated
- Doravirine + Secobarbital Contraindicated
- Elbasvir / grazoprevir + Secobarbital Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Secobarbital Contraindicated
- Isavuconazonium + Secobarbital Contraindicated
- Lonafarnib + Secobarbital 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 Secobarbital?
MediHelp rates the interaction as moderate. Fosphenytoin and Secobarbital 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. Secobarbital may alter phenytoin concentrations after fosphenytoin conversion, usually lowering them, and adds sedative effects. Changes in phenytoin levels can lead to loss of seizure control or toxicity.
How serious is the interaction between Fosphenytoin and Secobarbital?
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 free and total phenytoin levels and seizure control when starting or stopping secobarbital. Adjust the fosphenytoin dose accordingly.
What other medicines interact with Secobarbital?
MediHelp also lists interactions of Secobarbital with, for example, Calcium / magnesium / potassium / sodium oxybates, Doravirine, Elbasvir / grazoprevir. The full list is on the Secobarbital page.
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