Indications: all forms of epilepsy except absence seizures; less satisfactory in status epilepticus.

Cautions: avoid sudden withdrawal; children, elderly; impaired renal or hepatic function; severe respiratory depression; pregnancy, breast-feeding; porphyria; CNS depressants, alcohol.

Side Effects: hepatitis, cholestasis; hypotension; respiratory depression; behavioural disturbances, nystagmus, irritability, drowsiness, lethargy, depression, ataxia, paradoxical excitement, hallucinations, impaired memory and cognition, hyperactivity particularly in the elderly and in children; osteomalacia; megaloblastic anaemia (may be treated with folic acid), agranulocytosis, thrombocytopenia; allergic skin reactions; very rarely Stevens-Johnson syndrome and toxic epidermal necrolysis.

Special Precautions: CNS sedatives, particularly alcohol.

Dose: by mouth, 60-180 mg at night; Child, 5-8 mg/kg daily.

By IM injection, 200 mg repeated after 6 hours if necessary. Child, 15 mg/kg.

Status epilepticus, by IV injection (dilute injection 1 in 10 with water for injection), 10 mg/kg at a rate of not more than 100 mg/minute; max. 1 g.

Note: For therapeutic purposes phenobarbital and phenobarbital sodium may be considered equivalent in effect. Plasma-phenobarbital concentration for optimum response 15–40 mg/litre (60–180 micromol/litre)