Phenobarbital

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** A long-acting barbituric acid derivative with antipsychotic property. Phenobarbital binds to and activates the gamma-aminobutyric acid (GABA)-A receptor, thereby mimicking the inhibitory actions of GABA in the brain. The activation effects of the phenobarbital-receptor-ionophore complex include increased frequency of chloride channel openings, membrane hyperpolarization and ultimately synaptic inhibition and decreased neuronal excitability. In addition, this agent inhibits glutamate induced depolarization.

**Synonyms:** - 5-Ethyl-5-phenyl-2,4,6(1H,3H,5H)-pyrimidinetrione - PHENO - PHENOBARBITAL - phenobarbital