Diclofenac B-Cyclodextrin Binary Systems: A Study in Solution and in the Solid State

Diclofenac B-Cyclodextrin Binary Systems: A Study in Solution and in the Solid State
August 2003
Francesco Barbato, Brunella Cappello, Maria Immacolata La Rotonda and Fabiana Quaglia
Journal of Inclusion Phenomena and Macrocyclic Chemistry ssue: Volume 46, Numbers 3-4 Pages: 179 - 185
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Abstract
This study was carried out with the aim to optimize the dissolution propertiesof diclofenac (DIC) ? a non-steroidal anti-inflammatory drug sparingly solublein water ? through association -with beta-cyclodextrin (betaCD). The effect of betaCD on the aqueous solubility of DIC was evaluated by thephase solubility method. The amount of DIC dissolved increased linearly withthe addition of betaCD according to an AL type plot and without precipitationof the complex. The apparent stability constant of the complex, calculated supposinga 1:1 stoichiometry, was 295 M-1; this value was confirmed by circulardichroism analysis. DIC/betaCD interactions were also studied in water by1H and 13C NMR spectroscopy. Equimolar DIC/betaCD solid systems were prepared by physical-mixing, kneading, co-evaporation andfreeze-drying, and their properties in the solid state studied by DifferentialScanning Calorimetry, X-ray powder diffractometry and Fourier-TransformInfrared analysis. For sake of comparison, the mixture of DIC and betaCDseparately lyophilized was investigated too. The results demonstrated that thefreeze-dried product had the highest degree of amorphization and they were inagreement with the existence of an inclusion complex in the solid state. Thedissolution profiles of the drug from each solid system were affected by its physico-chemical properties, the freeze-dried being the most rapidly dissolvingforms.