SPL Set ID: b3ed0ef0-41de-46b1-af5f-4b940e74921b

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 and has the empirical formula C 12 H 12 N 2 O 3 . Its molecular weight is 232.24. It has the following structural formula: 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. Each 5 mL (teaspoonful) contains 20.0 mg phenobarbital. The elixir also contains FD&C Red #40, flavors, glycerin, purified water, sucrose, and alcohol 15%. Structural Formula