Enhancement of solubility of albendazole by complexation with β-cyclodextrin

• Main Authors: C. Moriwaki, G. L. Costa, C. N. Ferracini, F. F. de Moraes, G. M. Zanin, E. A. G. Pineda, G. Matioli
• Format: Article
• Language: English
• Published: Brazilian Society of Chemical Engineering 2008-06-01
• Series: Brazilian Journal of Chemical Engineering
• Subjects: Albendazole; Cyclodextrins; β-cyclodextrin; Complexation; Solubility
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322008000200005

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 (β-CD) using aqueous and acetic acid solutions as ABZ solubilizer was studied. In aqueous β-CD, complexation increased solubility 53.4 times, giving a complex equilibrium constant of 1266 L mol-1 with a maximum ABZ concentration of 276 µmol L-1 for 16.3 mmol L-1 β-CD. For complexation in 1.05 mol L-1 acetic acid, UV absorbance spectra and ¹H-NMR analysis confirmed complex formation. The UV absorbance of ABZ/acid acetic/β-CD solutions was modeled by the formation of two complexes with molar ratios 1:1 and 1:2 ABZ:β-CD. When neutralized with NaOH these solutions did not form precipitates only for the ABZ:β-CD molar ratios of 1:8 and 1:10, showing that ABZ solubility could be increased 306 times. Results show that high β-CD molar ratios hold ABZ in solution by complexation enhanced by the acetate anion.