Anticonvulsant
Pregnancy: D — teratogenic (cardiac defects, cleft palate); use if benefits outweigh risks
Phenobarbital
Brand names: Luminal, Phenobarbitone
Adult dose
Dose: Loading: 20mg/kg IV. Maintenance: 3–5mg/kg/day oral or IV
Route: IV or Oral
Frequency: Loading: single dose. Maintenance: once daily
Adult epilepsy maintenance: 60–180mg/day at night. Status epilepticus loading: 10–20mg/kg IV (up to 30mg/kg total).
Paediatric dose
Dose: 20 mg/kg
Route: IV
Frequency: Loading dose (single)
Max: 40mg/kg
Neonatal seizures: loading dose 20mg/kg IV over 20–30 min. Can repeat 10mg/kg up to 40mg/kg total. Maintenance: 3–5mg/kg/day. Neonatal doses may be higher per kg than adult.
Paediatric weight-based calculator
Neonatal seizures: loading dose 20mg/kg IV over 20–30 min. Can repeat 10mg/kg up to 40mg/kg total. Maintenance: 3–5mg/kg/day. Neonatal doses may be higher per kg than adult.
Clinical pearls
- First-line for neonatal seizures (per-hospital and NICU setting)
- Monitor respiratory function closely during IV loading — have resuscitation equipment ready
- Enzyme inducer: major drug interaction burden — check all concurrent medications
- Therapeutic level monitoring: neonates 15–40 mg/L; older children 15–40 mg/L; serum levels guide dosing
Contraindications
- Respiratory depression (relative)
- Acute intermittent porphyria
- Alcohol intoxication
Side effects
- Respiratory depression (loading dose)
- Sedation
- Enzyme induction (many drug interactions)
- Osteomalacia (long-term)
- Neonatal withdrawal
- Cognitive impairment (long-term)
Interactions
- Extensively induces CYP enzymes — reduces levels of: warfarin, oral contraceptives, phenytoin, valproate, lamotrigine, steroids
- Valproate — increases phenobarbital levels
Monitoring
- Serum phenobarbital levels (target 15–40 mg/L)
- Respiratory rate and SpO2 (during loading)
- EEG response
- LFTs (long-term use)
Reference: BNFc; RCPCH Neonatal Seizures Guidelines; BNF for Children. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.