Indications: absence seizures.

Cautions: avoid abrupt withdrawal; hepatic impairment; renal impairment; pregnancy; breast-feeding; avoid in porphyria.

Blood disorders Patients or their carers should be told how to recognise signs of blood disorders, and advised to seek immediate medical attention if symptoms such as fever, sore throat, mouth ulcers, bruising, or bleeding develop.

Side Effects: gastro-intestinal disturbances (including nausea, vomiting, diarrhoea, abdominal pain, anorexia, weight loss); less frequently headache, fatigue, drowsiness, dizziness, hiccup, ataxia, mild euphoria, irritability, aggression, impaired concentration; rarely tongue swelling, sleep disturbances, night terrors, depression, psychosis, photophobia, dyskinesia, increased libido, vaginal bleeding, myopia, gingival hypertrophy, and rash; also reported, hyperactivity, increase in seizure frequency, blood disorders such as leucopenia, agranulocytosis, pancytopenia, and aplastic anaemia (blood counts required if features of infection), systemic lupus erythematosus, and Stevens-Johnson syndrome.

Dose: initially 500 mg daily increased according to patient's needs by 250 mg at intervals of 4-7 days to usual dose of 1–1.5 g daily up to a max. of 2 g daily.

Child up to 6 years, 250 mg daily.

Over 6 years, 500 mg increased gradually to a max. of lg daily.