Stability of amitriptyline hydrochloride in a commercial aqueous solution

A commercial amitriptyline hydrochloride solution was stored at 80 degrees for up to 3 months. High-performance liquid chromatography showed no evidence of amitriptyline hydrochloride degradation. The method also indicated that two reported degradates, 3-(propa-1,3-dienyl)-1,2;4,5-dibenzocyclohepta-1,4-diene and dibenzosuberone, were present at levels less than 0.1% (the detection limit of the method) under the storage conditions. The stability of the commercial solutions is attributed to their relatively low ratio of headspace oxygen to amitriptyline hydrochloride.