Suitable water swellable hydrophilic polymers as osmotic agents include, but are not limited to, hydrophilic vinyl and acrylic polymers, polysaccharides such as calcium alginate, polyethylene oxide PEO, polyethylene glycol PEG, polypropylene glycol PPG, poly 2 hydroxyethyl methacrylate, poly acrylic acid, poly methacrylic acid, polyvinylpyrrolidone PVP, crosslinked PVP, polyvinyl alcohol PVA, PVA PVP copolymers, PVA PVP copolymers with hydrophobic monomers such as methyl methacrylate and vinyl acetate, hydrophilic polyurethanes containing large PEO blocks, sodium croscarmellose, carrageenan, hydroxyethyl cellulose HEC, hydroxypropyl cellulose HPC, hydroxypropyl methyl cellulose HPMC, carboxymethyl cellulose CMC and carboxyethyl, cellulose CEC, sodium alginate, polycarbophil, gelatin, xanthan gum, and sodium starch glycolate
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