GABAa receptors plasma

Increases GABA levels in plasma and CNS inhibits GABA catabolism, increases synthesis, and release can prevent GABA reuptake enhances the action of GABA at the GABAa receptor ... 

Felbamate appears to have multiple mechanisms of action. It produces a use-dependent block of the NMDA receptor, with selectivity for the NR1-2B sub-type. It also potentiates GABAa receptor responses. Felbamate has a half-life of 20 hours (somewhat shorter when administered with either phenytoin or carbamazepine) and is metabolized by hydroxylation and conjugation a significant percentage of the drug is excreted unchanged in the urine. When added to treatment with other antiseizure drugs, felbamate increases plasma phenytoin and valproic acid levels but decreases levels of carbamazepine. 

Phenobarbital Enhances phasic GABAa receptor responses reduces excitatory synaptic responses Nearly complete absorption not significantly bound to plasma proteins peak concentrations in Vi to 4 h no active metabolites tjy2 varies from 75 to 125 h Generalized tonic-clonic seizures, partial seizures, myoclonic seizures, generalized seizures, neonatal seizures, status epilepticus Toxicity Sedation, cognitive issues, ataxia, hyperactivity Interactions Valproate, carbamazepine, felbamate, phenytoin, cyclosporine, felodipine, lamotrigine, nifedipine, nimodipine, steroids, theophylline, verapamil, others... 

GABA inhibits the action of the locus ceruleus and this is mediated by the GABAa receptor-chloride channel system. The plasma and cerebrospinal fluid levels of GABA are low, and progabide, a GABAa receptor agonist, has antidepressant properties. 

Hansen GH, Belhage B, Schousboe A (1991) Effect of GABA agonist on the expression and distribution of GABAa receptors in the plasma membrane of cultured cerebellar granule cells an immunocytochemical study. Neurosci. Lett., 124, 162-165. 

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