The migration of cyanocobalamin upon drying of its wet granules was studied through the formulation of different granules using different diluents (lactose monohydrate and anhydrous dibasic calcium phosphate), different binders in different. concentrations; polyvinyl pyrrolidone (PVP k₂₅), hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), and gelatin at different drying temperatures (50°C and 70°C). Also, different layers of the dried granulation bed were separately compressed into their respective tablets and evaluated. The in vitro drug release from different formulated tablets was performed. The results showed that, granules prepared with dibasic calcium phosphate showed relatively a higher migration for the drug than those prepared with lactose. Also, drug migration decreased with increasing the binder concentration and viscosity.
Mottling was extensively observed for batches prepared with low viscous binder solutions, while, it is diminished on using a highly viscous binder solutions. The tablets prepared with 10 % w/w gelatin were found to be the least mottled ones. In addition, they showed least friability percentage, highest hardness value, highest disintegration time and lowest dissolution rate. However, those prepared with 0.5 % MC showed highest friability percentage, lowest hardness value, lowest disintegration time and high dissolution rate. Generally, increasing the binder concentration resulted in slowing both mottling and the in vitro drug release from tablets.