Development of a novel floating pulsatile system for chronotherapeutic release of diclofenac sodium

Abstract

The main objective of the present study was to develop a multiple-unit, floating-pulsatile drug delivery system for obtaining no drug release during floating and in the proximal small intestine followed by pulsed, rapid drug release in distal small intestine to achieve chronotherapeutic release of diclofenac sodium for treatment of rheumatoid arthritis. The system developed consists of drug containing core pellets prepared by extrusion-spheronization process, which were coated with an inner pH-dependent layer of Eudragit S100 and outer effervescent layer of sodium bicarbonate and HPMC K100M (Hydroxypropyl methylcellulose- K100M; HPMC; Methocel K100M premium, Colorcon Asia Pvt. Ltd., India). Developed formulations were evaluated for particle size analysis, friability, scanning electron microscopy, in vitro buoyancy studies and in vitro drug release studies. Outer effervescent layer prolongs the gastric residence time and inner layer prevents the drug release in acidic medium. Pellets showed instantaneous floating with no drug release in acidic medium followed by pulsed drug release in basic medium. Concentration of HPMC K100M and layering level of effervescent agent significantly affected performance of pellets. The system showed excellent lag phase followed by burst release in the distal small intestine which gives site and time specific delivery of diclofenac sodium which could serve in the chronotherapy of rheumatoid arthritis Keywords : Floating-pulsatile drug delivery; Chronotherapy; Diclofenac sodium; Rheumatoid arthritis Journal of Pharmacy and Bioresources Vol. 4 (2) 2007: pp. 32-38