RESUMO
The project is concerned mainly with the evaluation of two cellulose ether containing excipients, Aquacoat WG and Avicel 955 MCC for the improved extrusion-spheronization of metformin hydrochoride. Factorially designed experiments subject to statistical analyses were employed and products obtained were evaluated by sieve, packing density and image analysis, scanning electron microscopy and dissolution testing at pH 6.8. Aquacoat WG did not improve the ease of spheronization of drug mixes containing microcrystalline cellulose wetted with the optimum level of water. However, Avicel 955 MCC, which is a new experimental excipient containing 95% microcrystalline cellulose and 5% methylcellulose, did aid ease of spheronization facilitating acceptable yield of good spheres with high drug loadings (70%). Avicel 955 MCC containing drug mixes were more tolerant to minor alterations in level of hydration and yielded spheres which showed a small retardation of drug release despite the very high solubility of metformin hydrochloride.
