Attempting to prepare a convenient bioavailable formulation of vitamin B12 (cyanocobalamin), 17 tablet formulations were prepared by direct compression. Different concentrations of hydroxypropyl methyl cellulose (HPMC), carbopol 971p (CP971p), and chitosan (Cs) were used. The tablets were characterized for thickness, weight, drug content, hardness, friability, surface pH, in vitro drug release, and mucoadhesion. Kinetic analysis of the release data was conducted. Vitamin B12 bioavailability from the optimized formulations was studied on rabbits by the aid of enzyme-linked immunosorbent assay. Neurotone® I.M. injection was used for comparison. HPMC (F1-F4), CP971p (F5-F8), and HPMC/CP971p (F12-F15)-based formulations showed acceptable mechanical properties. The formulated tablets showed maximum swelling indices of 232 ± 0.13. The surface pH values ranged from 5.3 ± 0.03 to 6.6 ± 0.02. Bioadhesive force ranged from 66 ± 0.6 to 150 ± 0.5 mN. Results showed that CP971p-based tablets had superior in vitro drug release, mechanical, and mucoadhesive properties. In vitro release date of selected formulations were fitted well to Peppas model. HPMC/CP971p-based formulations showed bioavailability up to 2.7-folds that of Neurotone® I.M. injection.
Keywords: ELIZA; Vitamin B12; buccal tablets; carbapol; cyanocobalamin; mucoadhesive.