Design and In-vitro evaluation of gastro retentive drug delivery systems of metoprolol succinate

Gastro retentive drug delivery is a special approach that remains in the stomach for a prolonged period which helps to increase gastric residence time along with site specific drug delivery especially in the upper gastrointestinal tract (GIT) for local or systemic effects. Metoprolol succinate is a beta1-selective adrenergic receptor antagonist used to treat hypertension, angina and arrhythmia. It has a t1/2 of 3-7hrs and is mainly absorbed from the upper parts of GIT with good stability in the acidic environment. The main objective of the present study was to design a floating formulation having Metoprolol succinate as a model drug by using the polymers like HPMC K100M, HPMC K15M, HPMC K4M, Kollidon SR to increase the bioavailability of drug and reduce the dosing frequency. FTIR studies proved that there was no incompatability in the optimized formulations. All the formulations remained buoyant without any disintegration. The formulations F4, F8, F12 and F15 showed similar drug release to that of marketed formulation for a period of 12 hours. To ascertain the mechanism of drug release, in-vitro data was fitted into various release kinetic models like zero order, first order, Higuchi and Peppas. The values indicated, the non fickian diffusion with slow erosion of polymer matrix followed by drug diffusion and resulted in linear drug release profile over a prolonged period of time.