SPL Set ID: b0b862b9-235d-4a7c-ac4a-80d41c5a1b8b

The barbiturates are nonselective central nervous system (CNS) depressants that are primarily used as sedative-hypnotics. In subhypnotic doses, they are also used as anticonvulsants. The barbiturates and their sodium salts are subject to control under the Federal Controlled Substances Act. Phenobarbital is a barbituric acid derivative and occurs as white, odorless, small crystals or crystalline powder that is very slightly soluble in water; soluble in alcohol, in ether, and in solutions of fixed alkali hydroxides and carbonates; sparingly soluble in chloroform. Phenobarbital is 5-ethyl-5-phenylbarbituric acid. Phenobarbital is a substituted pyrimidine derivative in which the basic structure is barbituric acid, a substance that has no CNS activity. CNS activity is obtained by substituting alkyl, alkenyl, or aryl groups on the pyrimidine ring. It has the following structural formula: Each phenobarbital tablet contains 16.2 mg (1/4 grain), 32.4 mg (1/2 grain), 64.8 mg (1 grain) or 97.2 mg (11/2 grain) of phenobarbital. In addition each tablet contains: colloidal silicon dioxide, lactose monohydrate, magnesium stearate, microcrystalline cellulose and sodium starch glycolate. This is the image of the structual formula for Phenobarbital.