Generic
Phenobarbitone (Phenobarbital)
18 brands available in the market
At a glance
Phenobarbitone (Phenobarbital) is a barbiturate used for the treatment and prevention of epilepsy (seizures). It controls seizures by suppressing abnormal and excessive activity of nerve cells in the brain and also has sedative and hypnotic properties.
Description
Phenobarbitone is a short-acting barbiturate that depresses the sensory cortex, reduces motor activity, alters cerebellar function, and produces drowsiness, sedation, and hypnosis. Its anticonvulsant property is exhibited at high doses. It acts on GABAA receptors, increasing synaptic inhibition and elevating seizure threshold.
Indications
- Epilepsy/Seizures
- Sedation
- Insomnia (short-term)
Therapeutic class
Adjunct anti-epileptic drugs, Barbiturates
Pharmacological class
Barbiturate (Sedative-Hypnotic & Anticonvulsant)
Pharmacology
Phenobarbitone is a short-acting barbiturate that depresses the sensory cortex, reduces motor activity, alters cerebellar function, and produces drowsiness, sedation, and hypnosis. Its anticonvulsant property is exhibited at high doses. It acts on GABAA receptors, increasing synaptic inhibition and elevating seizure threshold.
Mechanism of action
Increases synaptic inhibition by acting on GABAA receptors, elevating seizure threshold.
Dosage
Adult Dose (Oral):
- Sedation: 30-120 mg daily in 2-3 divided doses; max 400 mg/day
- Insomnia (hypnotic): 100-320 mg; do not administer for >2 weeks
- Generalized tonic-clonic/Partial seizures: 60-180 mg/day at night
- Status epilepticus/Acute seizures: 100-300 mg/day at bedtime
- Elderly: Reduce dose
- Hepatic impairment: Reduce dose; Severe: Contraindicated
Pediatric Dose (Oral):
- Sedation: 2 mg/kg/day in 3 divided doses
- Status epilepticus/Acute seizures: 3-5 mg/kg or 125 mg/m²/day
- Neonates (>12 years): 1-3 mg/kg/day in 1-2 divided doses OR 50-100 mg BID/TID
- Preoperative sedation: 1-3 mg/kg
Injection Dose: Adult: Status epilepticus 200-600 mg or 15-18 mg/kg IV loading; Child: 15-20 mg/kg IV (max 2 mg/kg/min; max 1000 mg/dose)
Administration
- Oral: Take with or without food; take at a fixed time
- Injection: Administered by healthcare professional
- Swallow tablet whole; do not chew, crush or break
Missed dose
If you miss a dose, take it as soon as you remember; skip if it's almost time for next dose; do not double the dose.
Side effects
Common Side Effects:
- Drowsiness
- Nausea
- Diarrhea
- Hyperactivity
- Depression
- Confusion
- Decreased blood pressure
- Fatigue
- Headache
- Dizziness
- Constipation
- Excitement
- Hangover
Precautions & warnings
- May be habit-forming with long-term use
- May affect driving ability; do not drive if drowsy or dizzy
- Do not stop suddenly (may increase seizure frequency)
- Inform doctor if skin rash with fever occurs
- Inform doctor if joint pain or history of bone disease
- Caution in pregnancy and lactation
Contraindications
- Severe renal and hepatic disorders
- Severe respiratory depression, dyspnea, or airway obstruction
- Porphyria
- Pregnancy
Drug interactions
- Paracetamol overdoses: May enhance hepatotoxic potential
- CYP substrates (teniposide, methotrexate, antipsychotics, beta-blockers, calcium channel blockers, other anticonvulsants, chloramphenicol, cimetidine, corticosteroids, ciclosporin, doxycycline, estrogens, felbamate, griseofulvin, tacrolimus, furosemide, methadone, oral contraceptives, theophylline, TCAs, warfarin): May decrease levels/effects
- Chloramphenicol, felbamate, MAOIs, valproic acid: Reduced metabolism/increased toxicity
- Potentially fatal: Additive sedation and/or respiratory depression with ethanol, sedatives, antidepressants, opioid analgesics, benzodiazepines, and other CNS depressants
Food interactions
Alcohol consumption with Phenobarbitone is unsafe.
Use in pregnancy
Use in Pregnancy: Unsafe during pregnancy; definite evidence of risk to the developing baby; doctor may prescribe in life-threatening situations if benefits outweigh risks.
Pregnancy Category: D — always consult a doctor before taking during pregnancy.
Use in lactation
Use in Lactation: Probably unsafe; limited human data suggests drug may pass into breast milk; monitor baby for sleepiness, skin rash, and feeding issues.
Pediatric use
Pediatric dosing based on age and weight; consult your doctor.
Geriatric use
Elderly patients: Dose reduction may be needed.
Renal / hepatic impairment
Renal Impairment: Caution in kidney disease; dose reduction may be needed; severe renal disease not recommended.
Hepatic Impairment: Caution in liver disease; dose reduction may be needed; severe liver disease not recommended.
Overdose effects
Overdose: CNS and respiratory depression; 1 gram dose produces serious poisoning; 2-10 grams can cause death. Treatment: Supportive; immediate hospitalization required.
Storage conditions
Store below 30°C, away from light and moisture; keep out of reach of children.
Chemical structure
Phenobarbitone (Phenobarbital)