Concept and development of ophthalmic pseudo-latexes triggered by pH

Abstract The apparent p K a , acid value and maximum buffer capacity have been calculated for various polyacids generally utilized for enteric coating, in order to select a polymeric model compound for the preparation of pseudo-latexes triggered by pH for ophthalmic application. The solubility of the selected polymer (cellulose acetate phthalate) was estimated from a ternary plot of its solvents vs fractional solubility parameters. Pseudo-latexes were prepared by emulsification of various organic polymer solutions and removal of the solvents by vacuum distillation. The viscosity behaviour of 30% by weight pseudo-latexes was simulated in vitro to show the sharp and high increase of their viscosity vs pH.