Floating drug delivery.

Controlled release (CR) dosage forms have been extensively used to improve therapy with several important drugs. Oral controlled release and site specific drug delivery system has been of great interest in pharmaceutical field to achieve improved therapeutic advantage. Gastro retentive drug delivery system is one of such novel approaches to prolong gastric residence time, thereby targeting site specific drug release in the stomach for local or systemic effects. Gastric emptying of dosage forms is an  extremely variable process and ability to prolong and control the  gastric  emptying  time  is  a  valuable  asset  for  dosage  forms,  which  reside  in  the  stomach  for  a  longer  period  of  time  than  conventional  dosage  forms. Floating drug delivery systems are low-density systems that float over the gastric content and remain buoyant in the stomach for a prolonged period of time. They enhance drug bioavailability, reduce  drug  wastage  and  provide  controlled  drug  delivery  and  better  patient compliance. The recent developments  of FDDS including the physiological and formulation variables affecting gastric retention, approaches to design single -unit and multiple unit floating systems, and their classification and formulation aspects are covered in detail.