THE TERFENADINE BETA-CYCLODEXTRIN INCLUSION COMPLEX

Terfenadine (TFN) is a very hydrophobic antiallergic drug. It exists in three polymorphic and two solvated forms and is practically insoluble in water. These properties make a pharmaceutical formulation with acceptable biopharmaceutical characteristics difficult to prepare. Inclusion complexation with beta-cyclodextrin (betaCD) may eliminate such problems. The properties of the TFN/betaCD system have been studied in liquid, gaseous and solid phases by H-1 and C-13 NMR spectroscopy, powder X-ray diffractometry, differential scanning calorimetry and fast atom bombardment mass spectrometry. The solubility phase diagram was also recorded. In solution and in the gaseous phase the 1 : 1 complex prevails, whereas a 1 : 2 TFN/betaCD complex has been isolated by precipitation from homogeneous solution.