Glass formation in barbiturates and solid dispersion systems of barbiturates with citric acid

Glasses were prepared from a number of barbiturates. The viscosities and glass transition temperatures of the glasses were dependent on the structure of the groups present on the C-5 and N-1 atoms. Solid dispersions were prepared from three selected barbiturates formulated with citric acid. The glass transition temperatures of these systems indicated that a 1:1 molar ratio complex was formed between the two components and that intermolecular bonding was stronger in the complex than in the individual components.