Thermodynamics of the Amphiphilic Drug, Amitriptyline Hydrochloride-Surfactant/Polymer Systems at the Cloud Point

Abstract

Herein, we report the energetics of clouding in amphiphilic drug, amitriptyline hydrochloride (AMT—a tricyclic antidepressant drug), in the presense of surfactants and polymers. Surfactants/polymers are extensively used in drug delivery as drug carriers. The cloud point (CP) of an amphiphile can be considered as the limit of its solubility. The clouding components release their solvated water and separate out from the solution. Hence, the standard Gibbs free energy change of solubilization is evaluated from the relation . For all the additives, is found to be positive. However, and values are negative as well as positive depending upon the type and nature of the additive and the results are discussed on the basis of these factors.

Keywords:

• Amitriptyline
• amphiphilic drug
• cloud point
• Gibbs free energy change
• polymers
• surfactants

Md.S.A. is thankful to the Council of Scientific and Industrial Research (CSIR), New Delhi, India for the financial support in the form of Research Associate (No. 09/112(0420)/2008- EMR-I).