Enhancement of solubility of albendazole by complexation with β-cyclodextrin

A high dosage of albendazole (ABZ) is required for treating systemic helminthe infections because of its low solubility. Aiming at increasing ABZ solubility, complexation with beta-cyclodextrin (beta-CD) using aqueous and acetic acid Solutions as ABZ solubilizer was studied. In aqueous beta-CD, complexation increased solubility 53.4 times, giving a complex equilibrium constant of 1266 L mol(-1) with a maximum ABZ concentration of 276 mu mol(-1) L-1 for 16.3 mmol L-1 beta-CD. For complexation in 1.05 mol L-1 acetic acid, UV absorbance spectra and H-1-NMR analysis confirmed complex formation. The UV absorbance of ABZ/acidacetic/beta-CD Solutions was modeled by the formation of two complexes with molar ratios 1: 1 and 1:2 ABZ:beta-CD. When neutralized with NaOH these solutions did not form precipitates only for the ABZ:P-CD molar ratios of 1:8 and 1: 10, showing that ABZ solubility Could be increased 306 times. Results show that high beta-CD molar ratios hold ABZ in solution by complexation enhanced by the acetate anion. .