The liver metabolises many antiseizure medicines, and some antiseizure medicines can themselves injure the liver. Liver disease therefore affects both drug choice and interpretation of abnormal liver tests.
Hepatic metabolism varies widely between medicines
Some antiseizure medicines undergo extensive hepatic metabolism, while others are largely eliminated unchanged through the kidneys.
Severe liver impairment can reduce clearance, increase exposure or change protein binding, but the required adjustment is medicine-specific.
Enzyme induction adds another layer
Carbamazepine, phenytoin and phenobarbital are examples of older enzyme-inducing antiseizure medicines.
They can alter the metabolism of many other drugs, which becomes particularly relevant when a person with liver disease is taking multiple treatments.
Antiseizure medicines can cause liver injury
Drug-induced liver injury from antiseizure medicines ranges from mild biochemical abnormalities to rare severe hepatitis or acute liver failure.
Some reactions form part of systemic hypersensitivity syndromes such as DRESS and require urgent recognition.
Valproate deserves particular caution
Valproate has well-recognised hepatotoxic potential. Risk is especially important in young children with certain metabolic or mitochondrial disorders, but serious liver injury can occur outside those groups.
Known or suspected POLG-related mitochondrial disease is a major safety consideration.
Abnormal liver tests do not all mean the same thing
Some enzyme-inducing drugs can alter liver-enzyme measurements without causing clinically significant liver injury.
Interpretation therefore requires the pattern of abnormality, symptoms, timing, bilirubin and other clinical information.
Protein binding can alter measured concentrations
Low albumin in advanced liver disease can increase the free fraction of highly protein-bound drugs.
A total blood concentration may then underestimate the pharmacologically active exposure.
Newer drugs are not automatically risk-free
Recent reviews show that newer antiseizure medicines also differ substantially in hepatic dosing recommendations, and regulatory labels are not identical between regions.
Drug choice should therefore be based on the individual medicine rather than a simple ‘old versus new’ rule.
Related reading
Sources and further reading
- Antiseizure Treatments and Liver Injury: Expect (and Prevent) the Unexpected — 2026
- Pharmacokinetics, safety and dosing of newer ASMs in renal or hepatic impairment — 2026
Evidence checked: September 2026.