Chitosan and chitosan chlorhydrate based various approaches for enhancement of dissolution rate of carvedilol

The different formulations were prepared by different methods like solvent change approach to prepare hydrosols, solvent evaporation technique to form solid dispersions and cogrind mixtures. The prepared formulations were characterized in terms of saturation solubility, drug content, infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), electron microscopy, in vitro dissolution studies and stability studies.The practical yield in case of hydrosols was ranged from 59.76 to 92.32%. The drug content was found to uniform among the different batches of hydrosols, cogrind mixture and solid dispersions ranged from 98.24 to 99.89%. There was significant improvement in dissolution rate of carvedilol with chitosan chlorhdyrate as compare to chitosan and explanation to this behavior was found in the differences in the wetting, solubilities and swelling capacity of the chitosan and chitosan salts, chitosan chlorhydrate rapidly wet and dissolve upon its incorporation into the dissolution medium, whereas the chitosan base, less water soluble, would take more time to dissolve.This technique is scalable and valuable in manufacturing process in future for enhancement of dissolution of poorly water soluble drugs.The rate of absorption and bioavailability of poorly water soluble drugs is often controlled by the rate of dissolution of the drug in gastrointestinal tract. Many technological methods of enhancing the dissolution characteristics of slightly water soluble drugs have been reported in literature. These include reducing particle size to increase the surface area [1], solublization in surfactant system [2], formation of water soluble complexes [3], use of prodrug, drug derivatization and manipulation of solid state of drug substance to improve drug dissolution i.e. by decreasing drug crystallinity [4] or crystal engineering [5-7]. Chitosan is a linear polycationic copolymer of b [1-4] linked 2-acetamido-2-deoxy-b-D-glucopyranose