ArticleNeurocritical care2011
Valproic acid and warfarin: an underrecognized drug interaction.
Article in Neurocritical care, 2011. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 6 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
6 citing papers in PubMed, 38 citations in OpenAlex.
- Investigating the Relationship Between Anti-seizure Medications and Bleeding Disorders: A Comprehensive Review of the Current Literature.Drugs - real world outcomes · 2025Review
- Epidemiology, biology, and management of venous thromboembolism in gliomas: An interdisciplinary review.Neuro-oncology · 2023Article
- Evaluation of sodium valproate low dose efficacy in radicular pain management and it's relation with pharmacokinetics parameters.BioMedicine · 2020Article
- The critical interaction between valproate sodium and warfarin: case report and review.BMC pharmacology & toxicology · 2018Review
- Probable Interaction Between Warfarin and Divalproex Sodium.The Journal of pharmacy technology : jPT : official publication of the Association of Pharmacy Technicians · 2014Article
- Influence of ORM1 polymorphisms on the maintenance stable warfarin dosage.European journal of clinical pharmacology · 2013Article
Corrections and comments
PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.
Authors and funding
3 authors at 1 institution in 1 country.
Funding
No grant is acknowledged in the PubMed record.
Abstract
backgroundDrug interactions in the neurosciences intensive care unit (NICU) may involve antiepileptic drugs and warfarin. Most commonly used antiepileptic drugs are either potent hepatic enzyme inducers or inhibitors and they affect the metabolism of warfarin. Valproic acid also displaces warfarin from the protein binding sites resulting in significant INR changes but this type of drug interaction is less well known.
methodsCase report.
resultsA 71 year-old female patient with a glioblastoma multiforme presented to the NICU with refractory partial complex seizures. Patient was on warfarin for a prior deep venous thrombosis. After treatment with levetiracetam, seizures recurred and intravenous loading with valproic acid was administered, but resulted in a rapid increase in international normalized ratio (INR) to 7.6. A MRI of the brain showed hemorrhagic tumor, but no new major bleeding.
conclusionsWith both acidic drugs present, a loading dose of valproic acid may displace warfarin from the protein binding sites resulting in redistribution of warfarin in free active form and lead to a rapid increase in INR.
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Registered trials
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