RELATIONSHIP BETWEEN AGGREGATION OF HPMC COATED SPHEROIDS AND TACKINESS VISCOSITY/ADDITIVES OF THE COATING FORMULATIONS/

This study reports the relationship between the percentage of aggregat es formed during film coating of pellets in the Wurster process and th e tack force, viscosity, and cloud point of hydroxypropyl methylcellul ose (HPMC) coating formulations; mechanical strength of the HPMC cast films; and the release rate constant and dissolution T-50% values of t he HPMC coated spheroids. From the results, it is shown that the perce ntage of aggregates is associated linearly with the tack force and cor related in a nonlinear manner with the viscosity of the coating formul ations. However, there is no strong indication that percentage of aggr egates is correlated with cloud point, mechanical strength, dissolutio n T-50% value and release rate constant. Dissolution T-50% values demo nstrated a negative correlation with mechanical strength, cloud point and release rate constant. The incorporation of the plasticizers, poly ethylene glycol 400, triacetin and triethyl citrate, and film formers, vinylpyrrolidone/vinyl acetate copolymers and polyvinylpyrrolidone in the HPMC solution reduced the values of percentage aggregates, tack f orce and viscosity. The addition of thickener, methyl vinyl ether/male ic anhydride decadiene crosspolymer had the opposite effect.