Cefixime trihydrate is an orally active third generation cephalosporin having a wide range of activity. But its bioavailability is limited to about 40-50% after oral administration. The development of floating microspheres is a possible alternative to overcome this problem. The floating microspheres of cefixime were prepared with this objective using the biocompatible natural polymers like alginate and chitosan by ionotropic gelation method. A 3 2 full factorial experiment was designed to study the effect of independent variables such as alginate and chitosan concentration. The response parameters investigated are buoyancy and cumulative drug release percentage and was statistically analyzed by applying ANOVA. Contour plots and three-dimensional surface response plots were drawn to evaluate the interaction of the independent variables on the chosen dependent variables. Two optimal formulations were developed by setting the constraints on the independent variables to maximize the buoyancy and drug release percentage. The values of the observed responses are compared with those predicted by the mathematical models along with the % prediction errors. The low value of error proved the ability of response surface methodology to predict the behavior of the drug-loaded floating microspheres. Surface morphology of the microspheres was studied by SEM analysis. Kinetic studies reveal that the optimized formulations release the drug in the zero order manner with non-Fickian diffusion mechanism based on the regression values of zero order, Higuchi, and Korsmeyer-Peppas model.

Gastro retentive floating microspheres is a type of dosage form used as an efficient means of enhancing the bioavailability controlled delivery of many drugs that are mainly absorbed from the stomach and upper part of the intestine. Floating microspheres of cefixime trihydrate were prepared using polymers to prolong gastric residence time and increase drug bioavailability with decreased gastro intestinal side effects. The floating micro carriers were prepared by ionotropic gelation method by dispersing cefixime trihydrate with calcium carbonate and sodium bicarbonate separately into a mixture of anionic sodium alginate, as primary polymer with copolymers namely, HPMC K4M, HPMC K15M and ethyl cellulose into a solution of calcium chloride containing acetic acid. The prepared microparticles were evaluated for drug entrapment efficiency, particle size, buoyancy and in vitro drug release studies. As the amount of gas forming agents increased, the size and floating properties increased. The NaHCO3 loaded microspheres were large compared to those produced with CaCO3 but more buoyancy was shown by the microspheres formulated with CaCO3. The formulations without gas forming agents showed maximum entrapment efficiency. Drug release rate increased proportionally with addition of NaHCO3 but the increase in the concentration of CaCO3 did not make any change in the amount of drug release. From these studies we can conclude that CaCO3 is a more powerful gas forming agent than NaHCO3. The microspheres formulated with CaCO3 show increased buoyancy and controlled drug release which makes it excellent in floating drug delivery systems (FDDS).