Valproate

Valproic acid (valproate) is a drug that is used mainly to treat seizures or epilepsy, but is also prescribed to treat bipolar disease (manic depression) and to prevent migraine headaches, though this is an unlicensed use of valproate in the UK. It may be used in combination with other antiepileptic drugs, such as phenytoin or phenobarbital, to control certain kinds of seizures.

Routine therapeutic drug monitoring is generally unnecessary but may be occasioned when commencing, altering or stopping treatment. Primary indication is for assessment of compliance.
Suspected toxicity: gastrointestinal symptoms - diarrhoea, vomiting, nausea, tremors, mood-swings, bruising and bleeding, liver failure and pancreatitis. However, there is no clear relationship between toxic effects and plasma concentration.

There is a poor correlation between serum valproate levels and clinical response. Patients should be assessed individually based on clinical picture.