Title

Chlorpromazine Hydrochloride Micellization and the Thermodynamics of Aggregation in Aqueous Solution.

Authors

Shandiz Tehrani

Document Type

Article

Publication Date

1999

Abstract

The mean aggregate number (MAN) of the antipsychotic drug chlorpromazine hydro-chloride (CPZ) was investigated by fluorescence quenching. Using the intrinsic fluorescent properties of CPZ micelles and the quenching effect of 9-methylanthracene (9-MA), the MAN was determined to be ca. 30. A pronounced increase in aggregate size with in-creasing drug concentration (0.005-0.020 M CPZ) further confirmed the stepwise aggregation theory of CPZ. Increasing temperatures (>313 K) hindered the stability of larger micelles. Increasing electrolyte concentrations (0.0-0.4 M NaCl) resulted in increasing aggregate size, while higher osmotic pressures (0.0-0.3 M dextrose) had no significant effect on the micelle size. The enthalpy of micellization and demicellization for CPZ in a buffered solution were measured by differential scanning calorimetry. Post-micelle solutions of CPZ in buffer showed an abrupt, endothermic peak during upscans at ca. 318 E K. The peak was assigned as that of demicellization. Down scans revealed a broad peak due to the heat of micellization. Integration of peaks revealed changes in enthalpy values of -9 and 9 kJ per mole for micellization and demicellization respectively.

Advisor

P. K. Dea

Department

chem

Support

Support provided by:Beckman Scholars Program

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