Thermal decomposition investigation of paroxetine and sertraline

摘要

Antidepressants paroxetine and sertraline both as their hydrochlorides were studied regarding thermal behavior by TG/DTG-DTA, DSC, hot-stage microscopy, X-ray diffraction and coupled TG-FTIR. Paroxetine presented a single mass loss step after dehydration, in nitrogen. However, DTA curve revealed that such degradation actually occurs in three steps, in which HCl, piperidine, fluorobenzene and CO2 are released. In air decomposition took place in a similar way. DSC showed endothermic peaks related to melting and dehydration of paroxetine. During evolved gases analysis it was possible to observe overlapped signals related to HCl and piperidine absorption. Sertraline, on its turn, presented sublimation when slowly heated or alternatively a solid transition from Form II to Form III at c.a. 199 degrees C followed by two mass losses when heated at higher heating rates. In the first degradation step methylamine is released. The second step is related to the loss of tetraline, dichlorobenzene and HCl, as revealed by TG-FTIR. Based on these data, thermal decomposition mechanisms were proposed for both drugs.