Spectroscopic characterization and pharmacokinetic evaluation of amorphous solid dispersions of glibenclamide for bioavailability enhancement in Wistar rats.

Oral bioavailability of glibenclamide (Glb) was appreciably improved by the formation of an amorphous solid dispersion with Poloxamer-188 (P-188). Poloxamer-188 substantially enhanced the solubility and thereby the dissolution rate of the biopharmaceutics classification system (BCS) class II drug Glb and simultaneously exhibited a better stabilizing effect of the amorphous solid dispersion prepared by the solvent evaporation method. The physical state of the dispersed Glb in the polymeric matrix was characterized by differential scanning calorimetry, X-ray diffraction, scanning electron microscope and Fourier transform infrared studies. In vitro drug release in buffer (pH 7.2) revealed that the amorphous solid dispersion at a Glb-P-188 ratio of 1:6 (SDE) improved the dissolution of Glb by 90% within 3 h. A pharmacokinetic study of the solid dispersion formulation SDE in Wistar rats showed that the oral bioavailability of the drug was greatly increased as compared with the market tablet formulation, Daonil®. The formulation SDE resulted in an AUC ~2-fold higher. The SDE formulation was found to be stable during the study period of 6 months.