Valproic acid (sodium valproate, Dekapene®, Epival®, Apo-valproic®) is a drug used to control seizures in individuals with epilepsy. It is also prescribed to treat bipolar depression (bipolar disorder), to prevent migraines and, more rarely, to treat some chronic pain. It is sometimes used alone, but often in combination with other medications. The dose of valproic acid to be used to achieve a satisfactory effect varies from person to person and may even change over time. Valproic acid is metabolized by the liver, and many prescription or non-prescription drugs, nutritional supplements, vitamins and natural products can affect this metabolism and blood levels of the drug.
The optimum value range for valproic acid in the blood is 350 to 700 micromoles per litre (µmol/L) when samples are taken at least 10 hours after the last dose. Levels below 350 µmol/L do not usually relieve all symptoms (convulsions, unstable mood, migraines). Blood levels higher than 700 µmol/L can cause significant side effects (dizziness, shaking, drowsiness or lethargy, mood changes, confusion, etc.). Levels above 1000 µmol/L are of great concern and warrant prompt action to bring levels back down to an appropriate value.