Self-assembling of amphiphilic drug amitriptyline hydrochloride in the presence of additives: Role of surface activity in the pharmaceutical applications

Abstract

The aggregation behaviour of an amphiphilic antidepressant drug amitriptyline hydrochloride (AMT) has been studied to determine the micellar solution behaviour in the presence of polar (methanol and ethanol), dipolar aprotic solvents (acetone and 1,4 dioxane), salt (NaCl) and water structure-breakers (urea) at 298 K using electrical conductivity and surface tension measurements. From conductivity data, the ionization degree and counterion binding parameter of micelles have been determined. To better analyse influences of additives on micellar behaviour of AMT surface tension measurements were performed and surface properties of AMT i.e. maximum surface excess concentration and minimum area per surfactant molecule at the air/water interface were determined using Gibbs Adsorption Isotherm in the absence and presence of various amount of additives. Conductometric and surface tension measurements were successfully used in determination of critical micelle concentration (CMC) of AMT in aqueous media. The experimental results of AMT indicated that CMC values altered with the addition of additives. Micellization of AMT totally inhibited when methanol, ethanol, acetone, 1,4 dioxane and urea concentration reached a certain value while the CMC of AMT decreased with the increase in concentration of NaCl.