Gastroretentive Floating Microspheres Of Ketoprofen: in Vitro and in Vivo Evaluation

Rajeev Garg, Vijay Middha, & GD Gupta

Abstract: The present study involves preparation and evaluation of floating microspheres with Ketoprofen as model drug, for prolongation of gastric residence time. The microspheres were prepared by the solvent evaporation method using polymers hydroxypropylmethyl cellulose and ethyl cellulose. The prepared floating microspheres were evaluated for flow properties by calculating the angle of repose, compressibility index and various physicochemical parameters including particle size, percentage yield, entrapment efficiency, in vitro floating behavior, in vitro drug release studies. The shape and surface morphology of prepared microspheres were characterized by optical and scanning electron microscopy. The mean particle size increased with increasing ethyl cellulose concentration. The scanning electron microscopy confirms the hollow nature of microspheres with pores on the surface of floating microspheres, which imparts floating properties to the prepared floating microspheres. The prepared microspheres exhibited prolonged drug release of 12 h and remained buoyant. A gamma scintigraphy study was performed in rabbits to assess the in vivo gastric residence time of the optimized formulation. The optimized formulation showed the gastroretention of more than 6 hrs.

Introduction: Oral sustained drug delivery system is complicated by limited gastric residence time. Rapid gastrointestinal transit can prevent complete drug release in absorption zone and reduce the efficacy of administered dose since the majority of drugs are absorbed in stomach or upper part of small intestine dosage forms that can be retained in the stomach are called gastroretentive drug delivery systems (GRDDS). Gastroretentive floating drug delivery systems (GRFDDS) has bulk density lower than gastric fluids and thus remain buoyant in the stomach without affecting the gastric emptying rate for a prolonged period of time.While the system is floating on the gastric content, the drug is released slowly at a desired rate from the system. Both the single and multiple unit system have been developed.
Floating system made of multiple unit forms has relative merits compared to a single unit preparation. Indeed the gastric emptying of a multiparticulate floating system would occur in a consistent manner with small individual variations. On each subsequent gastric emptying sunk particle will spread out more uniformly over a large area of absorption sites, increasing the opportunity for drug release predictable way.4 Moreover, since each dose is consisting of many subunits, the risk of dose dumping is reduced. The concept of floating microspheres can also be utilized to minimize the irritant effect of weakly acidic drugs on stomach by avoiding direct contact with the mucosa and providing a mean of getting low dosage for prolonged periods. 


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