Drug interactions
Primidone + Tizanidine
Severity: Moderate
Primidone and Tizanidine: 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
Primidone is metabolised to phenobarbital, which induces hepatic enzymes and may lower tizanidine concentrations. Additive sedation is also possible.
What this interaction means in plain words
Primidone and Tizanidine 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.
Primidone belongs to Central Nervous System; Tizanidine belongs to Musculoskeletal.
Why it happens
Enzyme induction by primidone and its phenobarbital metabolite increases tizanidine clearance, with additive CNS depression.
What to do
Monitor spasticity control and increase the tizanidine dose gradually if needed. Monitor for sedation and hypotension.
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 Tizanidine
- Ciprofloxacin + Tizanidine Contraindicated
- Fluvoxamine + Tizanidine Contraindicated
- Pefloxacin + Tizanidine Contraindicated
- Pipemidic acid + Tizanidine Contraindicated
- Benzhydrocodone / acetaminophen + Tizanidine Major
- Brexanolone + Tizanidine Major
Other interactions of Primidone
- Lorlatinib + Primidone Contraindicated
- Lurasidone + Primidone Contraindicated
- Primidone + Ranolazine Contraindicated
- Primidone + Sofosbuvir-velpatasvir-voxilaprevir Contraindicated
- Primidone + Voriconazole Contraindicated
- Abiraterone + Primidone Major
Frequently asked questions
Can I take Primidone with Tizanidine?
MediHelp rates the interaction as moderate. Primidone and Tizanidine 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. Primidone is metabolised to phenobarbital, which induces hepatic enzymes and may lower tizanidine concentrations. Additive sedation is also possible.
How serious is the interaction between Primidone and Tizanidine?
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 spasticity control and increase the tizanidine dose gradually if needed. Monitor for sedation and hypotension.
What other medicines interact with Tizanidine?
MediHelp also lists interactions of Tizanidine with, for example, Ciprofloxacin, Fluvoxamine, Pefloxacin. The full list is on the Tizanidine page.
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