Decomposition of Amitriptyline Hydrochloride in Aqueous Solution: Identification of Decomposition Products

The decomposition of amitriptyline hydrochloride upon autoclaving in a buffered solution (pH 6.8) was investigated. Three major decomposition products [3‐(propa‐1,3‐dienyl)‐1,2: 4,5‐dibenzocyclohepta‐1,4‐diene, dibenzosuberone, and 3‐(2‐oxoethylidene)‐1,2:4,5‐dibenzocyclohepta‐1,4‐diene] were detected and identified by chromatographic and spectroscopic techniques. Evidence is presented that the latter two compounds are formed by further oxidation of 3‐(propa‐1,3‐dienyl)‐1,2:4,5‐dibenzocyclohepta‐1,4‐diene, and a possible decomposition pathway is outlined.