Spray-dried gastroretentive floating microparticles: preparation and in vitro evaluation

The full factorial design was employed to evaluate contribution of drug: polymer and Eudragit RS 100: Eudragit RL 100 on entrapment efficiency, time for maximum drug release, percentage of drug release. Floating microparticles were prepared using spray drying technique. Microparticles were evaluated for buoyancy and drug release study using paddle type dissolution apparatus using pH 1.2 buffer as dissolution medium. All the formulations showed good buoyancy with more than 90% microparticles floating for 12hrs. It was found that amount of polymer affected entrapment efficiency (P<0.05). Eudragit RS 100: Eudragit RL100 affected time for maximum drug release (P<0.05). The diffusion coefficient (n) value of the optimized formula was found to be 0.7042 which indicates mechanism of release is anomalous transport. Fourier Transform Infrared Spectroscopy and Differential Scanning Calorimetry studies showed that drug and excipients are compatible. Size of the microparticles ranged from 21-30 μM. Scanning electron microscopy showed that microparticles are spherical and non-aggregated. In this study it was found that spray drying can be used to produce floating microparticles successfully without use of solvents like dichloromethane, which is a class II solvent or aromatic solvents like ethyl acetate.