PVP solid dispersions for the controlled release of furosemide from a floating multiple-unit system.

The poor bioavailability of orally dosed furosemide (FUR) is due to the presenceof a biological window in the upper gastrointestinal tract. The purpose of the presentstudy was to develop and optimize in vitro a multiple-unit floating system with increasedgastric residence time for FUR. The incomplete release of FUR from theunits, related to its low water solubility, led to the preparation and evaluation ofdifferent FUR samples to be incorporated into the units. The complete dose releaseover the actual intragastric residence time of the system (about 8 hr) was achievedby loading both the core and the membrane forming the units with a 1:5 FUR/polyvinylpyrrolidone (FUR/PVP) solid dispersion. Physicochemical analyses suggestedthe predominant role of the amorphous state of FUR in producing enhanceddrug solubility and dissolution rate, which led to the desired release profile fromthe floating units