Drug interactions
Methsuximide + Phenobarbitone
Severity: Moderate
Methsuximide and Phenobarbitone: 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
Methsuximide (via its active metabolite) can raise phenobarbital serum concentrations. This may cause excess sedation and ataxia, while phenobarbital may also affect methsuximide metabolite levels.
What this interaction means in plain words
Methsuximide and Phenobarbitone 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.
Methsuximide belongs to Central Nervous System; Phenobarbitone belongs to Central Nervous System.
Why it happens
Likely inhibition of phenobarbital hepatic metabolism, and possible enzyme induction affecting methsuximide's metabolite.
What to do
Check phenobarbital serum concentrations when starting or stopping methsuximide and reduce the phenobarbital dose if toxicity appears. Watch for sedation and loss of seizure control.
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 Methsuximide
- Amisulpride + Methsuximide Moderate
- Amobarbital + Methsuximide Moderate
- Apalutamide + Methsuximide Moderate
- Asenapine + Methsuximide Moderate
- Brexpiprazole + Methsuximide Moderate
- Brivaracetam + Methsuximide Moderate
Other interactions of Phenobarbitone
- Cabotegravir + Phenobarbitone Contraindicated
- Doravirine + Phenobarbitone Contraindicated
- Isavuconazole + Phenobarbitone Contraindicated
- Darolutamide + Phenobarbitone Major
- Finerenone + Phenobarbitone Major
- Ivacaftor + Phenobarbitone Major
Frequently asked questions
Can I take Methsuximide with Phenobarbitone?
MediHelp rates the interaction as moderate. Methsuximide and Phenobarbitone 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. Methsuximide (via its active metabolite) can raise phenobarbital serum concentrations. This may cause excess sedation and ataxia, while phenobarbital may also affect methsuximide metabolite levels.
How serious is the interaction between Methsuximide and Phenobarbitone?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check phenobarbital serum concentrations when starting or stopping methsuximide and reduce the phenobarbital dose if toxicity appears. Watch for sedation and loss of seizure control.
What other medicines interact with Methsuximide?
MediHelp also lists interactions of Methsuximide with, for example, Amisulpride, Amobarbital, Apalutamide. The full list is on the Methsuximide page.
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