Drug interactions
Carbapenem + Valproic acid
Severity: Major
Carbapenem and Valproic acid: major interaction.
Last updated Sources: US FDA label
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 such as meropenem, imipenem and ertapenem cause a rapid and profound fall in serum valproate concentrations, often within 24 hours, to subtherapeutic levels. Breakthrough seizures and loss of seizure control have been reported in patients with epilepsy and in those taking valproate for other indications. The effect is not reliably overcome by raising the valproate dose and persists for days to a couple of weeks after the carbapenem is stopped.
What this interaction means in plain words
Carbapenem and Valproic acid can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Why it happens
Carbapenems are thought to inhibit acylpeptide hydrolase, which hydrolyses valproate glucuronide back to valproate, so that glucuronide is not recycled and valproate clearance rises. Reduced intestinal absorption and increased renal elimination of valproate may also contribute.
What to do
Avoid the combination and choose a non-carbapenem antibiotic whenever possible. If a carbapenem is essential, add an alternative antiseizure medication that is not affected, such as a benzodiazepine or levetiracetam, for the duration of treatment.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
- Depakote (divalproex sodium) Prescribing Information - Drug Interactions: Carbapenem Antibiotics — FDA Label
- Meropenem Summary of Product Characteristics - Interactions with valproic acid — EMA SmPC
Other interactions of Valproic acid
- Ertapenem + Valproic acid Contraindicated
- Imipenem / cilastatin / relebactam + Valproic acid Contraindicated
- Imipenem / cilastatin + Valproic acid Contraindicated
- Meropenem / vaborbactam + Valproic acid Contraindicated
- Meropenem + Valproic acid Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Valproic acid Major
Frequently asked questions
Can I take Carbapenem with Valproic acid?
MediHelp rates the interaction as major. Carbapenem and Valproic acid can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Carbapenems such as meropenem, imipenem and ertapenem cause a rapid and profound fall in serum valproate concentrations, often within 24 hours, to subtherapeutic levels. Breakthrough seizures and loss of seizure control have been reported in patients with epilepsy and in those taking valproate for other indications. The effect is not reliably overcome by raising the valproate dose and persists for days to a couple of weeks after the carbapenem is stopped.
How serious is the interaction between Carbapenem and Valproic acid?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination and choose a non-carbapenem antibiotic whenever possible. If a carbapenem is essential, add an alternative antiseizure medication that is not affected, such as a benzodiazepine or levetiracetam, for the duration of treatment.
What other medicines interact with Valproic acid?
MediHelp also lists interactions of Valproic acid with, for example, Ertapenem, Imipenem / cilastatin / relebactam, Imipenem / cilastatin. The full list is on the Valproic acid page.
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