Preparation and characterization of metformin hydrochloride controlled-release tablet using fatty acid coated granules

Metformin hydrochloride (MFM) is often used as a controlled-release (CR) tablet to reduce dosing frequency. However, the MFM CR tablet contains significant amounts of excipients and the tablet size is also large. Dosing convenience and patient compliance can be increased by reducing the size of the CR tablets. The aim of this study was to prepare and evaluate the MFM controlled-release tablet (MFM-CRT) using two types of release modulators, inner and outer. The MFM-CRT was prepared by coating the MFM granules using a binder solution containing aluminum stearate (ALS) as the inner release-modulator, and polyethylene oxide (PEO) as the outer release-modulator. The dispersion stability of the binder solution was optimized by the dispersion analyzer. The MFM-CRT was evaluated for dissolution rate and tablet volume. Additionally, dissolution behavior and dissolution kinetics of the MFM-CRT were analyzed using micro-computed tomography (micro-CT). Although the optimal MFM-CRT showed no difference in the release rate as compared to the commercially available product of Glucophage(R) XR 500 mg (f(2) value: 72), the length of the long axis was reduced by 6 mm and the weight was reduced by about 27%. We expect patient compliance to improve because of effective sustained release and volume reduction of MFM-CRT.