Interaction of amphiphilic drug amitriptyline hydrochloride with β-cyclodextrin as studied by conductometry, surface tensiometry and viscometry

Cyclodextrins are very well known to form the inclusion complexes with various drugs owing to their internal cavity. In this paper we have studied the interaction of beta-cyclodextrin (beta-CD) with amphiphilic drug amitriptyline hydrochloride (AMT) exploiting conductometry, surface tensiometry and viscometry. It was found that addition of beta-CD to the drug solution causes the shifting of micellization of amphiphilic drug toward higher concentrations. This confirms the complex formation between the drug and the host molecule as a result of the interaction between them. Surface tension isotherms suggest that the addition of beta-CD results in the surface tension of the solution to decrease as compared to the pure solution of drug due to the encapsulation of surface active drug inside the hydrophobic cavity of beta-CD. Similarly, viscosity of the solution decreases drastically on the addition of beta-CD which further increased on increasing the drug concentration. Free energy of micellization (Delta G(mic)) was computed with the help of degrees of micelle ionization obtained from the specific conductivity - [AMT] plots. (C) 2012 Elsevier B.V. All rights reserved.