Phenobarbital (Paediatric Epilepsy — Beyond Neonatal)

How it works

It potentiates GABA-mediated inhibition by prolonging chloride channel opening at the GABA-A receptor, raising the seizure threshold and reducing neuronal excitability.

Prescribing in practice

• Marked sedation, behavioural disturbance and cognitive/learning impairment are common in children and must be weighed against benefit, with abrupt withdrawal avoided because it can precipitate status epilepticus.
• It is a potent hepatic enzyme inducer that lowers levels of many co-administered drugs, including other anti-epileptics, corticosteroids and hormonal contraception in adolescents.
• Doses are weight-based and require titration; check against a children's formulary as requirements change with growth.

Monitoring

Monitor seizure frequency, sedation and behaviour, with plasma-level measurement reserved for suspected toxicity, poor control or adherence concerns.

Counselling the patient

• Do not stop the medicine suddenly as this can trigger seizures.
• Report excessive drowsiness, mood or behaviour changes, or a rash.
• Tell other prescribers about this medicine because it can reduce the effect of many other drugs.

Evidence & guidelines

Phenobarbital is a long-established anti-epileptic recognised by the World Health Organization as an essential medicine, though sedation limits first-line use where alternatives exist.