Phenobarbitone Capsule

Phenobarbitone (Phenobarbital) Capsules
Usage
Phenobarbitone capsules are an oral barbiturate anticonvulsant used for the management of seizure disorders and certain neurological conditions. It may also be used for its sedative properties in specific clinical settings.
They may be prescribed for:
• Epilepsy, including generalized and focal seizures
• Status epilepticus (in specialist settings)
• Seizure prophylaxis
• Sedation (less commonly used in modern practice)
• Veterinary use for seizure control in animals

Dosage
Dosage should be determined by the prescribing practitioner based on the patient’s condition, age, weight, and response.
Typical dosing considerations include:
• Usually administered once or twice daily
• Dose is often initiated at a low level and titrated gradually
• Capsules may be taken with or without food
• Blood levels may be monitored to ensure therapeutic range
Patients should take phenobarbitone consistently as prescribed and should not stop abruptly.

Mechanisms of Action
Phenobarbitone is a barbiturate that depresses central nervous system activity.
Its mechanisms include:
Enhancement of GABA activity
Phenobarbitone enhances the effects of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter.
Increased chloride ion influx
It prolongs the opening of GABA-A receptor–associated chloride channels, leading to neuronal hyperpolarisation.
Reduction of neuronal excitability
This suppresses abnormal electrical activity in the brain, helping to control seizures.

Contraindications
Phenobarbitone should not be used in patients with:
• Hypersensitivity to barbiturates
• Severe respiratory depression
• Porphyria
• Severe hepatic impairment

Precautions
Phenobarbitone should be used with caution in patients with:
• Respiratory disorders
• Hepatic or renal impairment
• History of substance misuse or dependence
• Elderly patients, who may be more sensitive to sedation
Additional considerations include:
• May cause sedation, dizziness, and cognitive impairment
• Risk of dependence and tolerance with long-term use
• May interact with many medications due to enzyme induction (CYP450)
• Abrupt discontinuation may lead to withdrawal symptoms or seizures
• Long-term use may affect bone health (e.g., vitamin D metabolism)
Patients should seek medical advice if they experience excessive drowsiness, breathing difficulties, or worsening seizures.

Storage
• Store below 25°C unless otherwise directed
• Keep capsules in a tightly closed container
• Protect from heat, moisture, and direct light
• Store securely due to potential for misuse
• Keep out of reach of children and pets
Patients should follow the storage instructions provided on the dispensing label supplied by the pharmacy.