The Effects of Temperature and Concentration on Micelle Formation of Chlorpromazine Hydrochloride.

Abstract

Chlorpromazine (CPZ) is an amphiphilic phenothiazine antipsychotic drug that has been used for the treatment of many different medical conditions, one of which is schizophrenia. Its chemical structure consists of a hydrophobic and hydrophilic region. Under certain conditions in solution, different molecules come together to form what is known as micelles, the aggregation of monomers. This study attempts to understand the formation and breakup of chlorpromazine hydrochloride micelles. Using the differential scanning calorimeter (DSC), we observed the micellization and demicellization of this drug. A 0.1 M phosphate buffer with a pH of 6.5 was used with varying amounts of CPZ. Under these experimental conditions, the critical micelle concentration has been reported to be 3.24 mM. Therefore, concentrations both above and below this concentration were used, ranging from .001 M to .10 M. At very high concentrations, there were multiple peaks present, suggesting that micelles may break up in many steps. It was also observed that the peak temperatures decreased with increasing concentration. The process of micellization and demicellization appears to be affected by both temperature and concentration.