Preformulation studies of glipizide: First step towards developing stable osmotic drug delivery system

The goal of this research study was to conduct a preformulation analysis of glipizide in order to establish a stable, robust as well as therapeutically effective system.

Glipizide was characterized to determine its flow properties. Solubility was determined in different pH-varying solvents and its purity was determined by infrared spectrum and absorption maxima. Standard UV curve was developed to aid in further analytical research studies. Finally loss on drying (LOD) and drug-excipients compatibility tests were performed.

Glipizide has poor flow and compressibility properties (BD 0.222 g/ml, TD 0.425 g/ml, Carr's index 47.78%, Hauser's ratio 1.915). Solubility of drug was found to increase with increase in pH. The purity of drug was confirmed by infrared spectrum which showed characteristics peaks and by uv spectroscopy which exhibited maxima at 276 nm. The standard curve obtained was linear with correlation coefficient (R² =0.998) and equation y = 0.0144x +0.0078. There were no drug excipient interactions which was clear as no visual changes in drug samples were observed with respect to discoloration, liquefaction and odor.

The drug candidate under consideration was pure glipizide which had poor flow property suggesting use of granulation technique during tablet manufacturing and it was stable with selected excipient at reported ratio at 40^oC/75% RH for 4 weeks.