EFFECT OF ADDED SUBSTANCES ON THEOPHYLLINE RELEASE FROM CARBOPOL 934PMATRIX

Formulations were prepared containing 50% theophylline, 10 to 30% Carb opol 934P in sodium acetate mixtures, 0.5% lubricant, with the remaind er of the formula consisting of spray-dried lactose. These formulation s were either prepared by direct compression or by wet granulation wit h phosphate buffer (pH 7.2). It was found that all the formulations pr oduced tablets successfully without sticking to the punches. The incor poration of sodium acetate with Carbopol in the tablets increased its effect as a sustained release matrix, but the use of buffer for wet gr anulation of the tablet powder did not. The drug release mechanism was dependent on the degree of gel formation, which in turn was dependent on the percentage of both the polymer and sodium acetate in the table t as well as the pH of the medium. Approximately 10% Carbopol 934P wit h 20% sodium acetate tablets provided the same sustained release mecha nism as 30% Carbopol 934P, but without sticking during compression.