Primarily used to treat seizures; also used to treat trigeminal neuralgia when first-line treatments (e.g. Carbamazepine) are not effective.

Variations CYP2C9 gene affect drug clearance. Divalproex should not be used as an alternative for Carbamazepine in patients with the HLA-B*1502 mutation which increases the risk of severe dermatologic reactions (toxic epidermal necrolysis and Stevens-Johnson syndrome). Avoid valproate in patients with hereditary neurometabolic syndromes caused by mutations in the gene for mitochondrial DNA polymerase gamma (POLG) (e.g., Alpers-Huttenlocher Syndrome)

Suicidal behavior or ideation; Antiepileptic drugs, including valproic acid, increase the risk of suicidal thoughts or behavior. Monitor platelet counts and coagulation tests. Measure ammonia level if unexplained lethargy and vomiting or changes in mental status, and also with concomitant topiramate use; consider discontinuation of valproate therapy. Hypothermia has been reported during valproate therapy with or without associated hyperammonemia that can also occur in patients using concomitant topiramate. Multi-organ hypersensitivity reaction; discontinue valproic acid. Somnolence in the elderly can occur; dosage should be increased slowly and with regular monitoring for fluid and nutritional intake.

• https://www.ncbi.nlm.nih.gov/pubmed/25967074
• https://www.ema.europa.eu/en/medicines?search_api_views_fulltext=valproat