... > SECTION VI - PRODUCTS OF THE CHEMICAL OR ALLIED INDUSTRIES > CHAPTER 29 - ORGANIC CHEMICALS > X. ORGANO-INORGANIC COMPOUNDS, HETEROCYCLIC COMPOUNDS, NUCLEIC ACIDS AND THEIR SALTS, AND SULPHONAMIDES > 2933 Heterocyclic compounds with nitrogen hetero-atom(s) only > Compounds containing a pyrimidine ring (whether or not hydrogenated) or piperazine ring in the structure > Allobarbital (INN), amobarbital (INN), barbital (INN), butalbital (INN), butobarbital, cyclobarbital (INN), methylphenobarbital (INN), pentobarbital (INN), phenobarbital (INN), secbutabarbital (INN), secobarbital (INN) and vinylbital (INN); salts thereof > Phenobarbital (INN), barbital (INN), and their salts