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

Herein, we report the energetics of clouding in amphiphilic drug, amitriptyline hydrochloride (AMTa 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 [image omitted] is evaluated from the relation [image omitted]. For all the additives, [image omitted] is found to be positive. However, [image omitted] and [image omitted] 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.