Valproate

Valproate is a prescription antiseizure medication, also used for bipolar disorder and migraine prophylaxis, sold as valproic acid, sodium valproate, or divalproex.

The drug has been used for decades and is metabolized mainly by the liver. Its known side effects include weight gain, tremor, hair loss, and, importantly, liver toxicity, and it carries warnings about hepatotoxicity, pancreatitis, and birth defects. Prescribers monitor liver enzymes and blood counts during treatment. Valproate is frequently combined with other antiseizure drugs in people whose seizures are difficult to control.

Valproate appears in cannabinoid discussions because clinical trials of prescription cannabidiol found that liver enzyme elevations were markedly more common in participants who were also taking valproate. The mechanism is not fully understood and does not appear to be a simple change in blood levels of either drug. Prescribing information for prescription CBD advises closer liver monitoring in this combination. It is one of the two best-documented CBD drug interactions, alongside clobazam, and a reason anyone on valproate is advised to consult a prescriber before using cannabinoids.