GASTRORETENTIVE EFFERVESCENT FLOATING TABLETS (GREFT) OF DRUGS ACTING ON CARDIOVASCULAR DISEASES

Incidences of Cardio Vascular Diseases (CVDs) are increasing in an alarming proportion in India. Conventional oral dosage forms cannot be retained in the stomach for long owing to gastric emptying. Moreover, drugs which are commonly employed in management of chronic CVDs either have reduced solubility at alkaline pH, undergo colonic degradation, exhibit site-specific absorption or varying bioavailability with combination therapy. Gastro-retentive drug delivery systems (GRDDS) are designed to overcome these challenges. Since 2006, Food and Drug Administration has approved only few GRDDS for treating CVDs. The aim of the present review is to summarize the outcomes of research carried on GRRDS with drugs for CVDs since last 15 y and comprehensive analysis of limitations of such studies due to which no product has been approved or commercialized in over last 18 y. Literature survey includes single unit, multi-particulate, monolayer and bilayer dosage forms with or without effervescence-inducing agents and made of natural and/or synthetic polymers like hydroxypropylmethyl cellulose, natural gums etc. Efforts have been made to compile in vitro buoyancy data such as floating lag time, total floating time, swelling index, release profile and release kinetics. Among various studies reported on monolayer and bilayer Gastro-Retentive Effervescent Floating Tablets, only 3 involved bioavailability studies in human volunteers. Toxicity studies in animals or stability studies are totally lacking. Observation with floating-type multi-particulate GRDDS is more disappointing. lack of safety, efficacy data, stability data, in vivo imaging studies and in vitro-in vivo correlation data might be actually responsible for lack of commercialization of any GRDDS for drugs acting on CVDs in 21st century.