Sodium valproate inhibits the breakdown and reuptake of the inhibitory neurotransmitter gamma aminobutyric acid (GABA).
This agent is useful in the primary generalised epilepsies, particularly petit mal. It is also useful in generalised tonic-clonic attacks, particularly those patients with a photosensitive EEG.
Sodium valproate is also useful in myoclonic epilepsy. It does not interfere with the oestrogen component of the contraceptive pill, unlike carbamazepine and the barbiturates.
Valproate is a possible treatment option for long term management in bipolar disorder*
NICE (1) suggest with respect to:
- when starting valproate, measure the person's weight or BMI and carry out a full blood count and liver function tests
- people taking valproate, and their carers, should be advised how to recognise the signs and symptoms of blood and liver disorders and to seek immediate medical help if any of these develop. Stop valproate immediately if abnormal liver function** or blood dyscrasia is detected
- prescribers should be aware of its interactions with other anticonvulsants (particularly carbamazepine and lamotrigine) and with olanzapine and smoking
The summary of product characteristics should be consulted before prescribing this drug.
Notes:
- * in September 2014 semi-sodium valproate had a UK marketing authorisation for this indication in people who have had mania that has responded to treatment with semi-sodium valproate. Sodium valproate did not have a UK marketing authorisation for this indication, although its use is common in UK clinical practice. The prescriber should follow relevant professional guidance, taking full responsibility for the decision. Informed consent should be obtained and documented
- ** although the absolute values of hepatic enzymes are a poor indicator of the extent of hepatic damage, it is generally accepted that if these are persistently elevated to over 3 times the upper normal limit, continuing to rise or accompanied by clinical symptoms, the suspected drug should be withdrawn. Raised hepatic enzymes of any magnitude accompanied by reduced albumin or impaired clotting suggest severe liver disease
- valproate treatment must not be used in girls and women including in young girls below the age of puberty, unless alternative treatments are not suitable and unless the conditions of the pregnancy prevention programme are met. Valproate must not be used in pregnant women
- with respect to stopping valproate in bipolar disorder (1):
- if stopping valproate, reduce the dose gradually over at least 4 weeks to minimise the risk of relapse
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