Physicochemical Characterization of Trazodone Hydrochloride Tetrahydrate

Abstract

Trazodone hydrochloride tetrahydrate was isolated and characterized by moisture absorption equilibrium, Karl Fischer method, powder X-ray diffractometry, infrared (IR) spectroscopy and elementary analysis. Trazodone hydrochloride (anhydrate) showed a supersaturation phenomenon in the dissolution process in water. In water and under high humidity condition (>93% relative humidity), trazodone hydrochloride was converted into the hydrate (trazodone hydrochloride: H20 = 1:4). The hydrate dehydrated under less than 51% relative humidity at 25 °C. The activation energy for dehydration reaction from the hydrate to the anhydrate determined by a non-isothermal method (Ozawa method) was 37.1 kcal/mol. © 1993, The Pharmaceutical Society of Japan. All rights reserved.