USP Dissolution Apparatus III (reciprocating cylinder) for screening of guar-based colonic delivery formulations

The reciprocating cylinder dissolution apparatus (USP Dissolution Apparatus III) was used to evaluate performance of several colonic delivery systems. Its dissolution tubes move between successive rows of vessels, allowing delivery systems to release drug in different media sequentially, i.e. simulated gastric fluids, simulated intestinal fluids, and simulated colonic fluids (SCF). The objective of this study was to assess USP dissolution apparatus III using formulations based on guar gum, a galactomannan polysaccharide. Drug (dexamethasone or budesonide) release in SCF was markedly increased at galactomannanase concentrations >0.01 mg/ml. The galactomannanase concentration and dipping speeds in the SCF were adjusted to produce dexamethasone release profiles similar to those estimated from absorption data in vivo. Thus, this dissolution setup may have predictive value for in vivo colonic delivery using guar gum-based colonic dosage forms.