Interactions between large organic ions of opposite and unequal charge. II. Ion pair and ion triplet formation

Solubility and thermodynamics of mesalazine in aqueous mixtures of poly ethylene glycol 200/600 at 293.2-313.2K

In this study, the solubility of mesalazine was investigated in binary solvent mixtures of poly ethylene glycols 200/600 and water at temperatures ranging from 293.2K to 313.2K. The solubility of mesalazine was determined using a shake-flask method, and its concentrations were measured using a UV-Vis spectrophotometer. The obtained solubility data were analyzed using mathematical models including the van't Hoff, Jouyban-Acree, Jouyban-Acree-van't Hoff, mixture response surface, and modified Wilson models. The experimental data obtained for mesalazine dissolution encompassed various thermodynamic properties, including ΔG°, ΔH°, ΔS°, and TΔS°. These properties offer valuable insights into the energetic aspects of the dissolution process and were calculated based on the van't Hoff equation.

[Enhancing effects of ion-pair complexes on skin permeation of cromolyn in vitro]

Lipophilic ion-pair complexes of 3-dl-alpha-tocopherylcarbonyl-1-n-alkyl-pyridinium-cromolyn (TAP-CG) were designed to enhance the percutaneous absorption of cromolyn (CG), and the effect of n-alkyl chainlength of the ion-pair complexes on the CG permeation through hairless mouse skin was evaluated in vitro. The permeation rates of CG were examined in isopropyl myristate (IPM) suspension using static Keshany-Chien type diffusion cells at 32 degrees C. The permeation parameters, steady-state flux, diffusion coefficient, partition coefficient between skin and IPM, and permeability coefficient were determined. Steady-state fluxes of CG increased linearly with the increasing n-alkyl chain-length of TAP-CG, and 3-dl-alpha-tocopherylcarbonyl-1-n-hexyl-pyridinium-cromolyn (THP-CG) produced the highest CG flux (0.62 +/- 0.11 nmol.cm-2.h-1), which was 14-fold greater than that of CG.Na in IPM suspension and more than 480-fold greater than that of CG.Na in aqueous solution due to increasing lipophilicity. In the case of TAP-CG with longer n-alkyl chainlength than THP-CG, however, the steady-state fluxes of CG decreased due to the high molecular weight and/or the high lipophilicity of the ion-pair complexes. It is suggested that lipophilic ion-pair complexes, especially THP-CG, are effective in absorption of cromoglicate through the skin. The results would be useful for studies on the role of each counterion in the lipophilic ion-pair complexes.

Assay of specific IgE antibodies to disodium cromoglycate in serum from a patient with an immediate hypersensitivity reaction

A 29-year-old man with pollen allergy had experienced immediate adverse reactions, such as itching of the eyes, rhinitis, wheezing, and general urticaria, after using disodium cromoglycate (DSCG) eye drops. The local symptoms were reproducible, and skin tests were strongly positive. With serum from the patient, a RAST was developed for the assay of IgE antibodies. The uptake on RAST disks was 6% of the total activity added, which was a significantly higher level than was found in sera from 35 randomly selected blood donors or in sera from 25 patients tolerating DSCG. By addition of DSCG to the patient's serum, 95% of the binding to paper disks could be inhibited. The induction of specific IgE antibodies was proposed to be a result of a combination of electrostatic and hydrophobic interaction of DSCG and a protein carrier. The substance would thus act as a hapten without any covalent binding to the carrier. DSCG may serve as a model for other nonreactive low-molecular-weight substances suspected to elicit type I-like adverse reactions.

Non-enhancement of sodium cromoglycate intestinal absorption by quaternary ammonium ions. An effect of salt on ion-pair formation?

Studies on the nature of rat small intestine perfusates indicate that this environment is thermodynamically unfavourable for the production of ion pairs between cromoglycate and alkylbenzyldimethylammonium ions. This is suggested as being the reason why, unlike previously found for ocular absorption of cromoglycate, these quaternary ammonium ions do not alter cromoglycate intestinal absorption.

Altered ocular absorption and disposition of sodium cromoglycate upon ion-pair and complex coacervate formation with dodecylbenzyldimethylammonium chloride

Ion-pair formation between the dianionic drug sodium cromoglycate and dodecylbenzyldimethylammonium chloride has been found to alter the extent and rate of corneal penetration of both large ions upon their coadministration. Additionally, using a complex coacervate of the two large ions as the applied dose form (in which the complex is in equilibrium with the ion pairs), a change in the overall disposition of both large ions to the various components of the eye is observed.