Drug interactions
Imipenem / cilastatin + Valproic acid
Severity: Contraindicated
Imipenem / cilastatin and Valproic acid: contraindicated 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
Carbapenems rapidly and substantially lower serum valproate concentrations, often within a day, and can precipitate breakthrough seizures. The effect may persist for days after the carbapenem is stopped and is not reliably overcome by raising the valproate dose.
What this interaction means in plain words
Imipenem / cilastatin and Valproic acid are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Carbapenems inhibit acylpeptide hydrolase, blocking hydrolysis of valproate glucuronide back to valproate, and may also reduce its absorption or increase its distribution into red cells.
What to do
Avoid the combination and use a non-carbapenem antibiotic. If a carbapenem is essential, add alternative anticonvulsant cover and monitor valproate levels and seizure activity.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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Other interactions of Valproic acid
- Ertapenem + Valproic acid Contraindicated
- Imipenem / cilastatin / relebactam + Valproic acid Contraindicated
- Meropenem / vaborbactam + Valproic acid Contraindicated
- Meropenem + Valproic acid Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Valproic acid Major
- Cilastatin-imipenem + Valproic acid Major
Frequently asked questions
Can I take Imipenem / cilastatin with Valproic acid?
MediHelp rates the interaction as contraindicated. Imipenem / cilastatin and Valproic acid are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Carbapenems rapidly and substantially lower serum valproate concentrations, often within a day, and can precipitate breakthrough seizures. The effect may persist for days after the carbapenem is stopped and is not reliably overcome by raising the valproate dose.
How serious is the interaction between Imipenem / cilastatin and Valproic acid?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and use a non-carbapenem antibiotic. If a carbapenem is essential, add alternative anticonvulsant cover and monitor valproate levels and seizure activity.
What other medicines interact with Valproic acid?
MediHelp also lists interactions of Valproic acid with, for example, Ertapenem, Imipenem / cilastatin / relebactam, Meropenem / vaborbactam. The full list is on the Valproic acid page.
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