Objectives: The effect of microwave (MW) irradiation and conventional heating (CH) on solid dispersion (SD) of poorly water-soluble glipizide (GPZ) and polyethylene glycol 4000 (PEG 4000) were studied in detail.
Methods: The chemical stability of GPZ on exposure to MW irradiation and CH was confirmed by high-performance liquid chromatography, Fourier transform infra red spectroscopy, proton nuclear magnetic resonance and mass spectroscopy studies. Comparative bioavailability studies were performed in rabbits using glipizide sustained-release tablets prepared using MW irradiation (MW-SD) or CH (CH-SD), with Glytop 2.5 mg SR as a reference.
Key findings: The MW-assisted melt mixing showed higher efficiency than CH in obtaining a homogeneous mixture having glass transparency. The polymorphic transformation of GPZ in each case was further confirmed by powder X-ray diffraction study. The solubility of GPZ in phosphate buffer pH 6.8 was greater for MW-SD (72.250 ± 0.154 μg/ml) than CH-SD (46 ± 0.201 μg/ml). The MW-SD matrix tablet (2.5 mg) displayed retarded drug release (releasing 99.320 ± 4.992% drug in 12 h). In-vivo pharmacokinetic study in rabbits revealed that the relative bioavailability of GPZ from MW-SD tablets improved greatly (153.73 ± 9.713%).
Conclusions: MW-induced SD technology could be a better alternative to CH-SD for the enhanced solubility and bioavailability of GPZ.
© 2012 The Authors. JPP © 2012. Royal Pharmaceutical Society.