Phenobarbitone is indicated for-

• Seizures
• Epilepsy

The use of barbiturates as sedative/hypnotics has largely been replaced by less toxic agents such as benzodiazepines.

Epilepsy

Seizure

Pediatric Oral Dosage

• Preoperative: 1 mg to 3 mg/kg.
• Anticonvulsant: 1 mg to 6 mg/kg per day

Adult Oral Dosage

• Daytime sedative: 30 mg to 120 mg daily in 2 to 3 divided doses.
• Bedtime hypnotic: 100 mg to 320 mg.
• Anticonvulsant: 50 mg to 100 mg 2 to 3 times daily.

Preoperative

For intramuscular or slow intravenous injection.

• Adults (≥18 years):  100 mg to 200 mg 60 to 90 minutes prior to surgery.
• Children (<18 years): 1 mg to 3 mg/kg 60 to 90 minutes prior to surgery.

Side effects associated with phenobarbitone sodium is as follows-

• Dizziness
• Headache
• Paradox
• Nausea
• Vomiting
• Abdominal pain
• Facial edema
• Purpura

Dizziness	Headache	Nausea
Abdominal Pain	Facial Edema	Purpura

• Administer with caution to pregnant women, myxedema, myasthenia gravis, patients with central nervous system depression, hypotension, severe anemia, hemorrhagic shock, cardiac, hepatic or renal impairment, asthma, diabetes mellitus, hyperkinesis tendencies.
•  Concomitant use of the following drugs should be avoided because of likely occurrence of adverse effects: alcohol, anaesthetics and CNS depressants and to a lesser extent, acetaminophen, oral anticoagulants, carbamazepine, oral contraceptives, estrogens, corticosteroids, digitalis, digitoxin, tricyclic antidepressants, cyclophosphamide, doxycycline, griseofulvin, monoamine oxidase inhibitors, phenytoin, quinidine, sodium valproate, valproic acid and vitamin D.  
• Because of the high risk of precipitating status epilepticus with attendant hypoxia and risk to both the mother and the unborn child, phenobarbital should not be stopped in patients who are taking it to prevent seizures. In the case of drugs used to treat minor seizures, the risk of stopping the medication prior to or during pregnancy should be weighed against the risk of congenital defects in the specific case and with the specific family history. To avoid over-sedation, lower doses are required in elderly and debilitated patients.
• Prolonged use of phenobarbital, even in therapeutic dosages, may result in psychologic and physiologic dependence. 
• In patients with impaired liver function or a history of drug dependence or abuse, phenobarbital should be used with caution. When the drug is administered in the presence of any respiratory difficulty, extreme caution is required. When administering phenobarbital to patients in whom the hypnotic effect may be prolonged or intensified, such as those suffering from shock, hepatic dysfunction, uremia, or following recent administration of other respiratory depressants, special precautions should be taken.
• Suicidal ideation and behavior have been reported in patients receiving antiepileptic drugs for a variety of indications.
• Phenobarbital is excreted in breast milk. Barbiturates concentrations in breast milk are 35 to 50% of maternal serum concentrations. In neonates, phenobarbital is eliminated slowly and may accumulate. As a result, the benefits of breast feeding should be weighed against the risks to the infant, and a decision should be made whether to discontinue nursing or phenobarbital, taking into account the drug's importance to the mother.