💊 Sodium Valproate

Sodium valproate is a broad-spectrum antiepileptic drug (AED) and a mood stabiliser. It is effective against various seizure types and is also used in the management of bipolar disorder.

Its mechanism of action is complex and multifactorial. It is thought to increase the concentration of gamma-aminobutyric acid (GABA) in the brain by inhibiting GABA transaminase and succinic semialdehyde dehydrogenase. It also blocks voltage-gated sodium channels and T-type calcium channels, contributing to its antiepileptic effects.

Sodium valproate is indicated for the treatment of generalised, partial, and myoclonic seizures. It is also used in the treatment of bipolar disorder, particularly for manic episodes and prophylaxis of mood episodes. In women of childbearing potential, its use is highly restricted due to significant teratogenicity.

Absolute contraindications include pregnancy (unless no other effective treatment is available and the benefits outweigh the risks), women of childbearing potential not on a highly effective contraception plan, and acute porphyria. It is also contraindicated in patients with severe hepatic dysfunction or a history of valproate-induced liver dysfunction. Pancreatitis is another contraindication.

Common adverse effects include nausea, vomiting, tremor, weight gain, and hair loss. Serious but less common effects include hepatotoxicity (especially in young children), pancreatitis, thrombocytopenia, and hyperammonaemia. Teratogenicity, particularly neural tube defects and developmental delay, is a major concern in pregnancy.

Baseline and regular monitoring of liver function tests (LFTs) and full blood count (FBC) is essential, especially during the first 6 months of treatment. Therapeutic drug monitoring may be performed to ensure levels are within the therapeutic range, though clinical response is often prioritised. Ammonia levels should be checked if encephalopathy is suspected.

For women of childbearing potential, ensure a comprehensive discussion about the Valproate Pregnancy Prevention Programme, including the need for highly effective contraception and regular review. Counsel all patients on potential side effects like tremor, weight gain, and hair loss. Warn about signs of liver problems (e.g., jaundice, abdominal pain) or pancreatitis and the importance of seeking urgent medical attention.

Valproate is highly teratogenic; avoid in women of childbearing potential unless absolutely necessary and strict contraception is in place. Be aware of the risk of hepatotoxicity, especially in children under 3. It's a broad-spectrum AED, useful for many seizure types. Remember the link to hyperammonaemic encephalopathy.

SBA questions frequently focus on the teratogenicity of valproate, particularly in women of childbearing potential, and the need for strict contraception and counselling. Scenarios might present a young woman with epilepsy or bipolar disorder and ask about the most appropriate drug choice or prescribing considerations. Questions may also test knowledge of serious adverse effects like hepatotoxicity or pancreatitis.