Formulation, Development and Evaluation of Floating Microsphere of Losartan Potassium Using Natural Polymer

Abstract

Floating drug delivery system is one of the novel drug delivery system. Floating drug delivery system have a bulk density less than gastric fluids and so remain buoyant in the stomach without affecting gastric emptying rate for a prolonged period of time. Various approaches have been used to retain the dosage form in stomach as a way of increasing the gastric residence time, including floatation systems, high-density systems, mucoadhesive systems, magnetic systems, unfoldable, extensible, or swellable systems and superporous hydrogel systems. The objective of this study was to prepare and evaluate floating microspheres of losartan potassium for the prolongation of gastric residence time. The microspheres were prepared by solvent diffusion–evaporation method using ethyl cellulose, hydroxypropylmethylcellulose and sodium alginate as natural polymers. Ethanol/dichloromethane blend was used as solvent in a ratio of 1:2. The floating microspheres were evaluated for flow properties, particle size, zeta potential, drug entrapment, as well as In-vitro release studies and stability studies. The shape and surface morphology of the microspheres were characterized by optical and scanning electron microscopy. The floating microspheres showed particle size, buoyancy, drug entrapment efficiency and yield in the ranges of 331.6 nm, 69±3 to 81±2%, and 60.25±0.25 to 75.65±0.74% and 69.98±0.56 to81.47±0.52%, respectively. Maximum drug release after 12 hr was 99.45 % for formulations F4. Scanning electron micrographs indicate pores both on the surface and interior of the microspheres.  Accelerated stability study was also performed for three months indicated that optimized formulation was stable. The developed losartan microsphere system is a promising floating drug delivery system for oral sustained administration of losartan.

Keywords: Losartan Potassium, Floating microspheres, Drug entrapment, In-vitro drug release, Ethyl cellulose, Hydroxyl propyl methylcellulose