Phenobarbital is 5-ethyl-5-phenylbarbituric acid. Phenobarbital can be a substituted pyrimidine spinoff in which the basic framework is barbituric acid, a compound which has no CNS activity. CNS action is received by substituting alkyl, alkenyl, or aryl teams to the pyrimidine ring. It's got the following structural components:Corticosteroids. Barb