Hydrophilic matrix system coated by polyvinyl acetate emulsion versus calcium alginate for sustained acetylsalicylic acid release.

Maize starch, polyvinyl alcohol, glucose, and magnesium stearate are used as tablet excipients, acetylsalicylic acid as probe, polyvinyl acetate, and calcium alginate as protective membranes. By changing the proportions of the excipients, the nature and the thickness of the protective membrane, it was possible to optimize the formulation of a controlled release tablet. The mechanism and the kinetics of release of the active ingredient are evaluated using kinetic models: zero order, Higuchi, first order, Hixson–Crowell and Krosmeyer–Peppas. The representation of the released quantities using Krosmeyer–Peppas seems to be the most appropriate to describe the release mechanism (R2 ~ 1). The k and n values, Krosmeyer–Peppas, indicate that drug release is complex. The release rate of the AI is controlled by the erosion of the membrane and the relaxation of the chains of polymers constituting it. The solubility parameters (δ), according to Hansen, of the hydroxylated ingredients, predict compatibility and stability. [ABSTRACT FROM AUTHOR]