Studies of floating dosage forms of furosemide: In vitro and in vivo evaluations of bilayer tablet formulations

For the purpose of enhancement the bioavailability of furosemide (FR), a fl oating dosage form with controlled release of FR was designed in this study . Because of the lower solubility of active material in the gastric medium, it was first enhanced by preparing an inclusion complex of FR with beta-cy clodextrin (beta-CD) in a 1:1 proportion using the kneading method. Followi ng the design of dosage form, bilayer floating tablets were prepared. After dissolution rate studies were performed using the continuous flow-through cell method, the formulation that provided delivery of active material near the target profile was given to six healthy male volunteer subjects, and i n vivo tests were performed. It was determined by radiographs that floating tablets prepared by adding BaSO4 stayed int he stomach for 6 hr. Further, values of the area under the plasma concentration-time curve (AUC) obtained with the floating dosage form were about 1.8 times those of the convention al FR tablet in blood analyses; maximum and minimum plasma concentrations w ere also found to be between the desired limits. In urine analyses, the pea k diuretic effect seen in classical preparations was decreased and prolonge d in floating dosage forms. Also, a considerably significant correlation wa s detected between in vivo results and in vitro data of the dissolution rat e, and it was concluded that the modified continuous flow-through cell meth od is usable for in vitro dissolution rate tests of floating dosage forms.