Phenobarbital Pediatric Dose — Anticonvulsant
Phenobarbital is a long-acting barbiturate anticonvulsant that exerts its effect by enhancing GABA-mediated inhibition and suppressing excitatory neurotransmission in the central nervous system. It is one of the most widely used antiepileptic agents in pediatrics, serving as a first-line or adjunctive treatment for neonatal seizures, status epilepticus, and chronic seizure disorders. Its predictable pharmacokinetics and availability in both IV and oral formulations make it a versatile option across inpatient and outpatient settings.
Pediatric Dosing
- Loading dose: 20 mg/kg IV as a single dose
- Maintenance dose: 5–10 mg/kg/day divided every 12 hours, administered IV or PO
The loading dose is given intravenously to achieve rapid therapeutic serum levels, typically targeted between 20–40 mcg/mL. Maintenance therapy is initiated after the loading dose to sustain seizure control.
Worked example — 10 kg child:
Loading dose: 10 kg × 20 mg/kg = 200 mg IV
Maintenance (mid-range 7.5 mg/kg/day): 10 kg × 7.5 mg/kg/day = 75 mg/day, given as 37.5 mg every 12 hours IV or PO. Consult institutional protocol for specific concentration and infusion preparation.
Indications and Clinical Context
Phenobarbital is indicated for the acute management and long-term suppression of seizures in pediatric patients, including neonatal seizures, febrile seizures, and generalized tonic-clonic seizures. It is considered a first-line agent for neonatal seizures per consensus neonatal neurology guidelines and is frequently employed in PICU and NICU settings for refractory or recurrent seizure activity. In older children, it may be used as adjunctive therapy when first-line anticonvulsants are insufficient.
The high loading dose of 20 mg/kg IV is intended to rapidly saturate CNS receptors and achieve therapeutic drug levels in acute or emergent scenarios. Maintenance dosing of 5–10 mg/kg/day divided every 12 hours supports sustained seizure prophylaxis with individualized titration based on clinical response and serum drug levels.
Administration and Monitoring
The loading dose should be administered intravenously and infused slowly; rapid IV administration increases the risk of respiratory depression, hypotension, and apnea, particularly in neonates and infants. Resuscitation equipment and monitoring should be immediately available. Maintenance doses may be given IV or transitioned to oral (PO) once the patient is tolerating enteral medications.
- Route: IV (loading and maintenance) or PO (maintenance)
- Monitoring: Continuous cardiorespiratory monitoring during IV loading; serum phenobarbital levels (therapeutic range typically 20–40 mcg/mL)
- Key adverse effects: Sedation, respiratory depression, hypotension, paradoxical hyperactivity in young children
- Contraindications: Known hypersensitivity to barbiturates; use with caution in hepatic impairment
- Max single dose: Not specified in source — consult institutional protocol
Disclaimer: This article is an educational reference summarizing standard pediatric dosing values. It is not a substitute for clinical judgment. Always verify doses against institutional protocols, the current edition of authoritative references (e.g., Lexicomp, Harriet Lane Handbook, PALS guidelines), the patient’s accurate weight, and any patient-specific factors (renal/hepatic function, allergies, comedications) before administration.