Relationship between aggregation of HPMC coated spheroids and tackiness/viscosity/additives of the coating formulations

Abstract

This study reports the relationship between the percentage of aggregates formed during from coating of pellets in the Wurster process and the tack force, viscosity, and cloud point of hydroxypropyl methylcellulose (HPMC) coating formulations; mechanical strength of the HPMC cast films; and the release rate constant and dissolution T(50%) values of the HPMC coated spheroids. From the results, it is shown that the percentage of aggregates is associated linearly with the tack force and correlated in a nonlinear manner with the viscosity of the coating formulations. However, there is no strong indication that percentage of aggregates is correlated with cloud point, mechanical strength, dissolution T(50%) value and release rate constant. Dissolution T(50%) values demonstrated a negative correlation with mechanical strength, cloud point and release rate constant. The incorporation of the plasticizers, polyethylene 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 force and viscosity. The addition of thickener, methyl vinyl ether/maleic anhydride decadiene crosspolymer had the opposite effect.