Phenobarbital is indicated as sedative & hence it relieves anxiety, tension & fear; hypnotic & hence it is used for short term insomnia, Pre-anaesthetics, Anti-epileptic in epilepsy with Partial seizure or Generalized Tonic-clonic seizure, Status epilepticus, anti convulsant.
anticonvulsants/hypnotics
Phenobarbital, the longest-acting barbiturate, is used for its anticonvulsant and sedative-hypnotic properties in the management of all seizure disorders except absence (petit mal). Phenobarbital acts on GABAA receptors, increasing synaptic inhibition. This has the effect of elevating seizure threshold and reducing the spread of seizure activity from a seizure focus. Phenobarbital may also inhibit calcium channels, resulting in a decrease in excitatory transmitter release. The sedative-hypnotic effects of phenobarbital are likely the result of its effect on the polysynaptic midbrain reticular formation, which controls CNS arousal.
Insomnia- Adults: 100 to 320 mg. Sedation- Adults: 30 to 120 mg/day in 2 to 3 divided doses. Epilepsy-Adults: 60 to 250 mg/day. Preoperative Sedation-Children: 1 to 3 mg/kg.
The concomitant use of Alcohol or other CNS depressants may produce additive CNS depressant effects.
Phenobarbital is contraindicated in patients with acute intermittent porphyria & who have a natural or idiosyncrasy to barbiturates. Phenobarbital is potentially habit forming if taken over an extended period of time. When being prescribed to overcome insomnia, the drug should not be used for a period longer than two weeks. Caution should be taken in patients, who are mentally depressed, have hepatic damage, suicidal tendencies or a history of drug abuse.
Drowsiness is the most common side Effect. Less common side Effects are CNS depression, nervousness, agitation, psychiatric disturbance, lethargy, mental depression, ataxia, nightmares, bradycardia, apnea, nausea, vomiting, constipation, restlessness & confusion in the elderly & hyperkinesia in children.
Contraindicated during pregnancy & lactation
The toxic dose of barbiturates varies considerably. In general, an oral dose of 1 gram of most barbiturates produces serious poisoning in an adult. Death commonly occurs after 2 to 10 grams of ingested barbiturate. Acute overdosage with barbiturates is manifested by CNS and respiratory depression Treatment of overdosage is mainly supportive and immediate hospitalization is necessary.
Keep below 30°C temperature, away from light & moisture. Keep out of the reach of children.
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