Name: Phenobarbital
Class: Antianxiety-Sedative-Hypnotic Agent (Barbiturate) (Antiepileptic:Tonic-Clonic)
Mechanism: Potentiates GABA transmission by interacting w/GABA receptor ® duration of channel opening. High doses ® direct activation of Cl- channel ® global CNS synaptic depression & block of sustained high freq. repetitive firing..
Absorption:
Dist.: 40-60% protein binding.
Metabolism.: Hepatic Metabolism ® inactive Metabolismolites. Signif. induction of hepatic microsomal enzymes ® potential for drug interactions.
Excretion, t½: 46-136 hr (adults), 37-173 hr (kids).
Toxicity/S.E.s: Dose-dependent depression of CNS fxn (mild sedation ® sleep ® coma ® coma w/resp. depression ® death), cognitive impairment, hyperactivity, ataxia, changes in sleep patterns. Non-dose-rel.—lethargy, ¯ attention span, osteopenia. Idiosync.—allergic dermatitis, Stevens Johnson synd., serum sickness rxn, granulocyte suppress. Chronic use of doses 2x-4x hypnotic dosage ® tolerance & psych/phys. dependence. W/drawal symptoms include grand mal seizures and DTs and are potentially lethal.
Utility: Alt. treatment for gen. tonic-clonic & partial seizures. Alt. treatment of status epilepticus. Rarely used as backup to other sedative-hypnotic drugs. Suicide.
Special Features: Long-acting agent