ABSTRACT
Reservoir systems, widely used for oral-controlled or sustained drug release, consist of a polymer coating on solid substrates (reservoir), such as powders, beads, granules, capsules, or tablets. Latex or pseudolatex presentations of waterinsoluble polymers have largely superseded the use of organic solvents for applying such coatings. Aqueous polymer dispersions are preferred on environmental and safety grounds, as solvents are not used during the coating process. These dispersions or aqueous polymer emulsions may be prepared by emulsion polymerization of a monomer (latex) or by emulsification of a polymer (pseudolatex). Dispersions of biopolymer derivatives, such as the cellulosics, can only be prepared as pseudolatices.
