Solute adsorption and concentration-dependent permeability in certain polymer films

Abstract

Certain parameters (solute adsorption, permeability and swellability) of films of a cationic acrylatemethacrylate copolymer have been determined as functions of the solute (sulphacetamide sodium) concentrations. Both permeability coefficients and the free (unadsorbed fraction of solute increased almost proportionately during increase in solute concentration 1-5%, above 5%, further increase in the fraction of free solute was slight, while the permeability coefficients decreased slightly. The solute also reduced film swellability but the observed concentration-dependent permeability related more to the adsorption phenomenon.

Preparation and Analgesic Activity of Eudragit RS100® Microparticles Containing Diflunisal

“…Thus, at pH values higher or lower than the pK a of the drug (D3.3), the electrostatic interaction with the polymer active sites is hampered because of the greater dissociation state of the drug (at pH > 6) or of the polymer carboxyl groups (at pH 2). At pH 4 an optimal interaction between the two components occurs, limiting the diffusion/dissolution of the drug from the microparticle network [25][26][27].…”