betadex and gliquidone

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.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; alpha-Cyclodextrins; Animals; beta-Cyclodextrins; Biological Availability; Calorimetry, Differential Scanning; Crystallography, X-Ray; Cyclodextrins; Drug Carriers; Drug Compounding; Freeze Drying; Hypoglycemic Agents; Male; Rats; Rats, Wistar; Skin Absorption; Solubility; Spectrophotometry, Infrared; Sulfonylurea Compounds

Gliquidone, a second generation sulfonylurea has been investigated for transdermal delivery. The poor aqueous solubility of the drug prompted the use of hydroxypropyl-beta-cyclodextrin (HP-beta-CD), a cyclic oligosaccharide, which is known to facilitate transdermal permeation of many drugs by enhancing the solubility and thus improving the diffusible species of the drug molecules at the skin-vehicle interface. In order to optimize the transdermal delivery of gliquidone, the effect of pH along with complexation on the solubility and permeation has been investigated. The solubility profiles of the drug, on increasing the concentration of HP-beta-CD were of Higuchi's AL type at the three pH values evaluated. However, the solubilization slope of the drug at pH 7.0 was 22 times that at pH 3.0 as a result of greater intrinsic solubility of the ionized form of the drug at pH 7.0. Transdermal flux of gliquidone at pH 7.0 was significantly greater than the flux at pH 3.0 in the presence of 15% w/v HP-beta-CD, attributable to the better solubility of the drug at pH 7.0 in the presence of HP-beta-CD. The effect of increasing concentrations of HP-beta-CD investigated at variable drug loading in the donor phase at pH 7.4 endorsed the earlier observations from studies on other drugs, that the drug has to be present at saturation in HP-beta-CD aqueous vehicle to achieve an optimized flux. While at saturation, the steady state flux of gliquidone from the aqueous HP-beta-CD (25% w/v) vehicle was enhanced 31 times compared to pure drug suspension at pH 7.4, unsaturation in the donor phase resulted in the decreased flux of gliquidone. It was concluded from the present study that enhanced transdermal flux of gliquidone can be achieved by adjusting the pH and the concentration of HP-beta-CD to achieve a better solubility of the drug.

Topics: 2-Hydroxypropyl-beta-cyclodextrin; Administration, Cutaneous; Animals; beta-Cyclodextrins; Cyclodextrins; Diffusion; Hydrogen-Ion Concentration; Hypoglycemic Agents; Pharmaceutical Vehicles; Rats; Skin Absorption; Solubility; Spectrophotometry, Ultraviolet; Sulfonylurea Compounds; Thermodynamics