THE INFLUENCE OF FORMULATION FACTORS ON THE RELEASE OF THE METOPROLOL TARTRATE FROM EXTENDED RELEASE TABLETS

The aim of this study was to formulate and evaluate oral sustained drug delivery systems for metoprolol tartrate using hydrophilic polymers. The matrix tablets were prepared with different types and ratios of polymers and diluents. The polymers selected for formulations were hydroxypropyl methylcellulose (HPMC) in concentration of 20%, 30%, alone or combined with sodium carboxymethylcellulose (CMC-Na) in 1:1 ratio. The diluents varied depending on the preparation technique: lactose monohydrate (Pharmatose 200M) for wet granulation method and microcrystalline cellulose (Avicel (R) 102), pregelatinized starch (Starch (R) 1500), agglomerated a-lactose monohydrate (Tablettose (R) 80) and calcium phosphate dihydrate for the direct compression method. The matrix tablets were evaluated for mass variation, friability, hardness, thickness, swelling index, and in vitro dissolution. The effect of some formulation variables on the release rate of metoprolol tartrate from polymeric systems has been investigated. The increasing amount of HPMC in the formulation led to a slow release of drug.