Preparation and in vitro characterization of non-effervescent floating drug delivery system of poorly soluble drug, carvedilol phosphateThe objective of the study was to enhance the solubility of carvedilol phosphate and to formulate it into non-effervescent floating tablets using swellable polymers. Solid dispersions (SD) of carvedilol were prepared with hydrophilic carriers such as polyvinylpyrrolidone and poloxamer to enhance solubility. Non-effervescent floating tablets were prepared with a combination of optimized solid dispersions and release retarding polymers/swellable polymers such as xanthan gum and polyethylene oxide. Tablets were evaluated for physicochemical properties such as hardness, thickness and buoyancy. SD prepared with the drug to poloxamer ratio of 1:4 by melt granulation showed a higher dissolution rate than all other dispersions. Formulations containing 40 mg of polyethylene oxide (C-P40) and 50 mg xanthan gum (C-X50) were found to be best, with the drug retardation up to 12 hours. Optimized formulations were characterized using FTIR and DSC and no drug and excipient interactions were detected.Keywords: carvedilol phosphate, solid dispersion, non-effervescent, floating tabletsCarvedilol phosphate is a non-selective beta-blocker, prescribed for the treatment of angina, hypertension and congestive heart failure. The reported systemic bioavailability of carvedilol phosphate is 24 % after oral administration (1). The drug reaches peak plasma concentration in 1-2 h with an elimination half-life of 7 to 10 h (1, 2). This drug has a narrow absorption window in the upper gastrointestinal tract and it would benefit from a gastroretentive delivery system. Floating drug delivery system (FDDS) is a gastroretentive system that can be effervescent or non-effervescent. Wu et al. (3) prepared floating sustained release tablets of nimodipine using HPMC and PEG 6000. Prior to formulation of floating tablets, nimodipine was incorporated into a poloxamer-188 solid dispersion, whereafter it was directly compressed into floating tablets. It was observed that by increasing the HPMC and decreasing