In vitro dissolution of different brands of griseofulvin tablets.

An in vitro dissolution rate test was developed for possible use in formulation design and control of griseofulvin tablets. Dissolution profiles of five brands of griseofulvin tablets were obtained using a two-phase system consisting essentially of a 11 three-necked round-bottom flask. Appropriate sink conditions in the aqueous phase were maintained by means of an upper organic phase composed of a mixture of equal parts of benzene and chlorobenzene. The dissolution media tested were 0.02% polysorbate 80 in water (pH = 6--7), sodium desoxycholate (10 mmol/1) in water (pH = 7.2) and 0.02% polysorbate 80 in HCl (0.1 mol/l, pH = 2). Interbrand differences in dissolution were better seen in neutral medium containing the non-ionic surfactant. Reduced deaggregation tendencies of griseofulvin in acid medium and unfavourable partitioning conditions in the presence of bile salt masked the differences in dissolution in the other two media. Dissolution profiles obtained under sink conditions could be characterized by rate constants.