THE TERFENADINE BETA-CYCLODEXTRIN INCLUSION COMPLEX

Terfenadine (TFN) is a very hydrophobic antiallergic drug. It exists i n three polymorphic and two solvated forms and is practically insolubl e in water. These properties make a pharmaceutical formulation with ac ceptable biopharmaceutical characteristics difficult to prepare. Inclu sion complexation with beta-cyclodextrin (betaCD) may eliminate such p roblems. The properties of the TFN/betaCD system have been studied in liquid, gaseous and solid phases by H-1 and C-13 NMR spectroscopy, pow der X-ray diffractometry, differential scanning calorimetry and fast a tom bombardment mass spectrometry. The solubility phase diagram was al so recorded. In solution and in the gaseous phase the 1 : 1 complex pr evails, whereas a 1 : 2 TFN/betaCD complex has been isolated by precip itation from homogeneous solution.