Enhancement of dissolution and oral bioavailability of gliquidone with hydroxy propyl-beta-cyclodextrin

The virtual insolubility of gliquidone in water results in poor wettability and dissolution characteristics, which may lead to a variation in bioavailability. To improve these characteristics of gliquidone, binary systems with hydroxypropyl-beta-cyclodextrin (HP-beta-CD) were prepared by classical methods such as physical mixing, kneading, co-evaporation and co-lyophilization. The solid state interaction between the drug and HP-beta-CD was assessed by evaluating the binary systems with X-ray diffraction, differential scanning calorimetry and IR- spectroscopy. The results establish the molecular encapsulation and amorphization of gliquidone. The phase solubility profile of gliquidone in aqueous HP-beta-CD vehicle resulted in an A(L) type curve with a stability constant of 1625 M(-1). The dissolution rate of binary systems was greater than that of pure drug and was significantly higher in the case of co-lyophilized and co-evaporated systems. Upon oral administration, [AUC]-alpha was significantly higher in case of co-lyophilized (2 times) and co-evaporated systems (1.5 times) compared to pure drug suspension while other binary systems showed only a marginal improvement. The study ascertained the utility of HP-beta-CD in enhancing the oral bioavailability of gliquidone, and points towards a strong influence of the preparation method on the physicochemical properties.