Multicomponent diffusion in (cyclodextrin-drug plus salt plus water) systems: {2-Hydroxypropyl-β-cyclodextrin (HP-βCD) plus KCl plus theophylline plus water}, and {β-cyclodextrin (βCD) plus KCl plus theophylline plus water}

The Taylor dispersion technique was used to measure values of mutual diffusion coefficient in aqueous solutions of {2-hydroxypropyl-beta-cyclodextrin (HP-beta CD) + KCl + theophylline (THP) + water}, and {beta-cyclodextrin (beta CD) + KCl + theophylline (THP) + water} at T = 298.15 K at equimolar carrier concentrations of (0.002, 0.005, and 0.010) mol . dm (3), for each solute. We determined the nine multicomponent diffusion coefficients for these systems, D-123(11), D-123(22), D-123(33), D-123(12), D-123(13), D-123(21), D-123(23), D-123(31), and D-123(32), and compared them with those previously obtained for the corresponding ternary and binary systems. Coupled diffusion of those components, as indicated by cross-diffusion coefficients, D-123(12), D-123(13), D-123(21), D-123(23), D-123(31), and D-123(32), are discussed in terms of salting-out effects, as well as the possible formation of both theophylline-metal ion or cyclodextrins-metal ion complexes. (C) 2012 Elsevier Ltd. All rights reserved.