phenobarbital

Antiepileptics. Barbiturates

ATC code: N03AA02 (Phenobarbital)

Brand names

Luminal, Solfoton, Phenobarbital sodium

Mechanism of action

Allosterically enhances GABA-A signaling, prolongs chloride channel opening. Essential Medicines List for epilepsy, especially in resource-limited settings. Replaced by newer antiepileptics in developed countries due to sedation and CYP induction. In Russia, present in combination OTC sedatives (Corvalol, Valocordin) – chronic use causes dependence and cognitive impairment.

Indications

Neonatal seizures

First line

Phenobarbital remains the first-line drug for neonatal seizures per international and Russian guidelines. Loading dose 20 mg/kg IV; if seizures persist, additional 10 mg/kg. Maintenance dose 3–5 mg/kg/day. Seizure control 40–60%; if ineffective, add phenytoin or levetiracetam. includes phenobarbital in the Essential Medicines List for neonatal seizure treatment.

After seizure control, gradually transition to long-term antiepileptics with better neurodevelopmental profile (levetiracetam, lamotrigine).

Practical notes

Dose titration

For epilepsy in adults: starting dose 50–100 mg 2–3 times daily orally, maintenance 100–300 mg/day. Target plasma level 15–40 µg/mL. In children: 3–5 mg/kg/day. In neonates with seizures: loading dose 20 mg/kg IV. Due to long half-life, steady state is reached at 2–3 weeks. Once-daily dosing is sufficient in some patients.

Monitoring

Monitor plasma phenobarbital level (target 15–40 µg/mL) at 2–3 weeks after initiation, with dose changes, and when adverse effects occur. Complete blood count, liver function tests, 25(OH) vitamin D – annually with long-term therapy. In children, assess neurocognitive development. In patients on long-term therapy (over 5 years), bone mineral density.

Special situations

When discontinuing after long-term use, taper gradually by 10–25% every 2–4 weeks. Abrupt withdrawal causes severe symptoms with anxiety, insomnia, seizures, delirium, and risk of fatality. Phenobarbital is a strong CYP3A4 inducer and reduces effectiveness of oral contraceptives, warfarin, many antibiotics, and immunosuppressants. Avoid combining with alcohol, opioids, benzodiazepines without compelling indication due to severe respiratory depression risk. Regular Corvalol or Valocordin use (over 30–60 mL/day) causes dependence – this behavior requires addiction medicine consultation.

Common myths

Myth: "phenobarbital in Corvalol is safe, people have used it for heart problems for decades". Fact: regular Corvalol, Valocordin, and similar products cause physical phenobarbital dependence. Withdrawal causes anxiety, insomnia, seizures. Additionally, bromide accumulates with bromism (mental disturbances, dermatitis, tremor). For cardiac symptoms, see a cardiologist, not Corvalol.

Myth: "phenobarbital is outdated and no longer used". Fact: remains first-line for neonatal seizures. Included in Essential Medicines List.

Myth: "one can drive after Corvalol". Fact: phenobarbital and bromide impair concentration and reaction time for 24–48 hours; with regular use this effect is constant.

Frequently asked

What is phenobarbital used for?

phenobarbital is evaluated for the following indications with varying evidence strength: Status epilepticus (evidence tier A), Neonatal seizures (evidence tier A), Focal epilepsy (evidence tier B). See the full indication matrix with dosing and citations above on this page.

What are the side effects of phenobarbital?

Common side effects of phenobarbital (≥ 1 in 100): Sedation, drowsiness, fatigue, Incoordination, dizziness, Cognitive impairment, especially in children and elderly, Paradoxical excitement in children, Depressed mood. See the Safety section for uncommon and serious reactions.

Is phenobarbital safe during pregnancy?

FDA category D. FDA category D. First-trimester use carries risks of cleft palate, cardiac defects, and digital hypoplasia; third-trimester use of hemorrhagic disease of the newborn and neonatal withdrawal. Women of reproductive age are switched to safer antiepileptics (levetiracetam, lamotrigine). If therapy continues, give folic acid 4–5 mg/day and vitamin K1 (phytomenadione) to the mother in the last month and to the newborn after birth.

Is phenobarbital compatible with breastfeeding?

Passes into breast milk at 36–100% of maternal plasma level. LactMed advises caution and infant monitoring (sedation, poor feeding). Breastfeeding may need to be limited if infant develops significant symptoms.

Who should not take phenobarbital?

phenobarbital is contraindicated in: Hypersensitivity to barbiturates; Severe respiratory insufficiency; Severe hepatic impairment; Acute intermittent porphyria; History of substance use disorder. Full list in the Safety section.

phenobarbital in Corvalol is safe, people have used it for heart problems for decades

regular Corvalol, Valocordin, and similar products cause physical phenobarbital dependence. Withdrawal causes anxiety, insomnia, seizures. Additionally, bromide accumulates with bromism (mental disturbances, dermatitis, tremor). For cardiac symptoms, see a cardiologist, not Corvalol.

phenobarbital is outdated and no longer used

remains first-line for neonatal seizures. Included in WHO Essential Medicines List.

one can drive after Corvalol

phenobarbital and bromide impair concentration and reaction time for 24–48 hours; with regular use this effect is constant.

phenobarbital

Mechanism of action

Indications

Neonatal seizures

Status epilepticus

Focal epilepsy

Acute anxiety, short-term treatment

Practical notes

Dose titration

Monitoring

Special situations

Common myths

Drug–nutrient interactions

Vitamin B12

Folate

Vitamin D

Vitamin K

Safety

Contraindications

Serious adverse effects

Common adverse effects

Uncommon adverse effects

PregnancyFDA D

Breastfeeding

Frequently asked