Effect of molecular structure on the hydration of structurally related antidepressant drugs

Abstract

Apparent molal volumes and adiabatic compressibilities of aqueous solutions of the amphiphilic cationic antidepressant drugs butriptyline and doxepin hydrochlorides have been determined from density and ultrasound velocity measurements in the temperature range 20–50°C. Critical concentrations for aggregation of these drugs were obtained from ultrasound velocity measurements. Negative deviations from the Debye–Hückel limiting law of the apparent molal volume were obtained from both drugs in all temperature ranges, except for doxepin at 50°C, which provides evidence of no pre-association at concentrations below the critical concentration. Apparent molal adiabatic compressibilities of the aggregates formed by these drugs were typical of those corresponding for an aggregate formed by a stacking process.

Acknowledgements

The authors thank Ministerio de Ciencia y Tecnología for research project MAT2004-27056 and Xunta de Galicia for additional financial support. M.A.C. thanks financial support from Pakistan Government.

Notes

§Permanent address: Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan

Additional information

Notes on contributors

M. A. Cheema§

§Permanent address: Department of Chemistry, Quaid-i-Azam University, Islamabad, 45320, Pakistan