Development and Evaluation of Novel Tabletted Microspheres for Controlled Release of Glimepiride

Purpose: To design and evaluate sustained release microspheres incorporated in orally disintegrating tablet for anti-diabetic drug Glimepiride and compare it with conventional tablet. Method: Glimepiride was encapsulated with different amount of ethyl cellulose polymer by an emulsion solvent evaporation technique and the physicochemical properties of the formulation were characterized. Spherical microspheres with particle size 125 – 250 μm were prepared. Optimization was done using 32 randomized full factorial design (Software used: Statease Design-Expert). Microspheres were characterized by Scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction. A single dose randomized study was conducted on male wistar rats for bioequivalance testing. A single blind study was conducted for taste masking test and disintegration time in human volunteers. Results: The formulations were evaluated for pharmacokinetic parameters. The optimized formulation gave Cmax value more than conventional tablet. The controlled release of drug also provides for higher plasma drug content and improved bioavailability. Particle size was dependent on stirring speed and drug release was dependent on polymer concentration. The in vitro drug release was studied in two different pH media (pH 1.2 for 2 hours, pH 6.8 up to 12 hours). The drug release mechanism of optimized formulation can be explained with first order model which describes the concentration dependent drug release. The entrapment efficiency of these formulations was 80 – 100 %. Microspheres obtained showed good flow properties. The major factors influencing % entrapment efficiency and % drug release were found to be polymer concentration and stirring speed, respectively.