Formulation and Evaluation of Bilayer tablets of Metoprolol Succinate

Metoprolol is β-1 blocker drug and used in treatment of angina pectoris and hypertension. Metoprolol 100mg tablets were formulated as a modified release oral system by utilizing the concept of bilayer tablets in which 30mg drug was added as immediate release (IR) and 70 mg as extended Release (ER). The IR layer consists of lactose or microcrystalline cellulose which acts as diluents with sodium starch glycolate or crosscarmellose as superdisintegrant. The blend was evaluated for angle of repose, bulk and tapped density, Hausner's ratio, Carr's index. The bilayer tablets were prepared manually using 9 station tablet punching machine. The prepared bilayer tablets were evaluated for hardness, thickness, friability, uniformity of weight and in vitro dissolution study. The bilayer tablets were also examined for drug content, kinetic of drug release and stability study. The results showed that the immediate release layer comprising MCC and 2% SSG released 95% drug in 60mins. The sustained release layer was prepared by three polymers i.e. HPMC K 100, HPMC K 15M and HPMC K 4M. It was found that HPMC K 4M in 20% concentration sustained the release of metoprolol succinate to 12hrs. It was concluded that batch BL-3 exhibited desirable properties and optimized drug release. The in vitrodrug release of batch BL-3 was satisfactory. Hence batch BL-3 was considered as optimized batch.