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Potential interaction between valproic acid and doripenem
Thaddaus R Hellwig1, Mallory L Onisk, Bret A Chapman
1Department of Pharmacy Practice, South Dakota State University College of Pharmacy, 1305 W. 18th Street, Sioux Falls, SD 57117-5039, USA. Thaddaus.hellwig@sanfordhealth.org
Current Drug Safety
|January 19, 2011
Summary
Concomitant administration of valproate and doripenem may significantly lower valproic acid levels. This drug interaction, observed in two patients, led to substantial reductions in valproic acid concentrations.
Area of Science:
- Pharmacology
- Clinical Pharmacy
- Neuropharmacology
Background:
- Valproate (VPA) is a widely used antiepileptic drug with a narrow therapeutic index.
- Maintaining therapeutic valproic acid concentrations is crucial for seizure control and efficacy.
- Doripenem is a broad-spectrum carbapenem antibiotic.
Observation:
- Two distinct cases of concurrent valproate and doripenem therapy are presented.
- In both cases, patients experienced significant decreases in valproic acid serum concentrations after initiating doripenem.
- The observed reduction in valproic acid levels was 62% in the first patient and 69% in the second.
Findings:
- Concomitant use of doripenem with valproate resulted in marked reductions in valproic acid concentrations.
- The magnitude of VPA level decrease suggests a clinically significant pharmacokinetic interaction.
- This interaction occurred in patients receiving intravenous valproate for seizure management.
Implications:
- Clinicians should be aware of the potential for doripenem to reduce valproate efficacy.
- Therapeutic drug monitoring of valproic acid levels is recommended when co-administered with doripenem.
- Further studies are warranted to elucidate the mechanism of this drug interaction and guide management strategies.
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