Sodium valproate

Sodium valproate works primarily by calming overactive nerve signals in the brain. It does this in two ways: by blocking channels that allow electrical signals to spread between nerve cells, and by increasing levels of a natural brain chemical called GABA that has a settling effect. This double action is why doctors prescribe it for epilepsy and also for mania—those settling effects on brain activity help with both conditions. It's usually given as tablets or liquid, though if someone can't swallow for a period, it can be given by injection into a vein.

The medication stays active in the body for roughly eight to twelve hours, though this varies quite a bit between individuals. It's processed by the liver, and here's something important: sodium valproate slows down several liver enzymes that break down other medications, which means it can affect how well other drugs work or cause unexpected interactions. If your family member takes other regular medications, their doctor will need to monitor them carefully.

Common side effects include nausea—this happens quite frequently—and tremor, which also affects many people. Weight gain is common. Some people develop low platelet counts or mild anaemia, which is why blood tests are usually part of routine monitoring. These are generally manageable, but they're worth watching for.

The serious risks are less common but important to know about. Liver problems, including potentially fatal liver failure, have occurred in some people taking sodium valproate. Inflammation of the pancreas has been reported uncommonly, usually in the first six months, and can occasionally be life-threatening. Rarely, severe skin reactions or bone marrow problems have happened. Sometimes the medication causes high ammonia levels in the blood that can affect how the brain works, causing confusion or other changes in thinking.

There's a significant set of restrictions around who should not take sodium valproate. It should not be used during pregnancy unless absolutely no other treatment will work, because it can cause serious harm to the developing baby, including birth defects. Women and girls who could become pregnant need detailed information from their doctor about these risks and must use effective contraception if they're prescribed this medication. Sodium valproate is also contraindicated for people with current or past liver disease, certain genetic conditions affecting the liver or metabolism, and several other specific medical conditions. If your family member has been prescribed this medication, their doctor will have checked that none of these apply.

A Behaviour Support Practitioner reviewing this medication is likely checking whether it's being used primarily to manage behaviour rather than to treat the medical condition it was prescribed for—in other words, whether it's functioning as a chemical restraint. That review looks at the original reason for prescribing, whether the dose has crept up over time in response to behaviours, and whether the benefit still justifies the risks, particularly given the serious potential side effects.

Sodium valproate is a fatty acid derivative anticonvulsant with antimanic properties. Its mechanism involves blockade of voltage-dependent sodium channels and augmentation of brain GABA levels; the GABAergic effect is thought to contribute to mood stabilisation. Plasma half-life is typically 8–12 hours (range 3.84–15.77 hours) in adults. Sodium valproate inhibits multiple hepatic enzymes—including cytochrome P450, glucuronyl transferase, and epoxide hydrolase—and displaces drugs from plasma protein binding sites, making it prone to clinically significant interactions. PBS-listed indications are epilepsy and mania in patients temporarily unable to take oral therapy, with prescribing restricted to certain practitioners when the condition is stable.

Contraindications are extensive: pregnancy and women of childbearing potential unless no suitable alternative exists and counselling about teratogenic risk has been documented; pre-existing or familial severe hepatic dysfunction; known hypersensitivity; urea cycle disorders; uncorrected systemic primary carnitine deficiency; hepatic porphyria; and mitochondrial disorders due to POLG mutations (including Alpers-Huttenlocher syndrome), with additional caution in children under two years suspected of POLG-related pathology. Common adverse effects include nausea, tremor, weight gain, thrombocytopaenia, and anaemia. Serious but less common risks include hepatic failure (sometimes fatal), pancreatitis (typically within six months of initiation), bone marrow failure, severe cutaneous reactions (TEN, SJS, DRESS, erythema multiforme), and hyperammonaemia with neurological symptoms. Intramuscular injection risks tissue necrosis and is contraindicated.