γCD/HPγCD: Synergistic solubilization

The natural gamma-cyclodextrin (gamma CD) is like linear water-soluble dextrins, and unlike the natural alpha- and beta-cyclodextrins (alpha CD and beta CD), digested by salivary and pancreatic amylase. This gives gamma CD a very favorable toxicological profile. However, its usage is hampered by its relatively low solubilizing effect and tendency to form turbid solutions. Addition of 2-hydroxypropyl-gamma-cyclodextrin (HP gamma CD) to aqueous gamma CD solutions increases the complexation efficiency of gamma CD and reduces the turbidity. For example, 80:20 mixture of gamma CD and HP gamma CD is up to 50% more effective solubilizer for dexamethasone and hydrocortisone than expected based on the solubilizing effects of the individual cyclodextrins. Mixing alpha CD or beta CD with their more water-soluble derivatives only resulted in additive effects. Mixing gamma CD with HP gamma CD resulted in synergistic effect. (c) 2008 Elsevier B.V. All rights reserved.