Drug migration during drying of tablet granulations II: effect of binder solution viscosity and drying temperature

The effect of binder solution viscosity and drying temperature on the integranular migration of propoxyphene hydrochloride was studied. Wet granulations containing the drug were prepared using binder solutions with viscosities ranging from 1 to 1000 cps. Temperature studies were conducted using granulations prepared with a 3-cps binder solution and dried at 40, 50, 60, 70, and 80 degrees. Drug migration decreased with increased binder solution viscosity, and insignificant migration occurred in granulations prepared with binder solutions having apparent viscosities above 90 cps. No significant effect on intergranular drug migration was observed within the drying temperature range studied. Tablets compressed from a granulation in which drug migration was high showed a greater tablet-to-tablet drug content variation than a granulation with lower migration, even though each dried granulation was thoroughly mixed before tableting.