Identification of the Photodegradation Products of the Tricyclic Antidepressant Drugs Clomipramine and Doxepine

Székely P¹, Gyéresi Á², Hancu G², Laczkó Zöld Eszter³, Vancea Szende⁴

1 Department of Pharmaceutical Marketing, University of Medicine and Pharmacy, Tîrgu Mureş, Romania
2 Department of Pharmaceutical Chemistry, University of Medicine and Pharmacy, Tîrgu Mureş, Romania
3 Department of Pharmacognosy, University of Medicine and Pharmacy, Tîrgu Mureş, Romania
4 Department of Physical Chemistry, University of Medicine and Pharmacy, Tîrgu Mureş, Romania

Objective: Isolation and identification of the photodegradation products of the tricyclic antidepressant drugs clomipramine and doxepine after irradiation with ultraviolet light.
Methods: The photodegradation products were separated by a thin layer cromatographic method, followed by scraping the spots from the chromatoplate and extracting in methanol, which was followed by their identification by mass spectrometry.
Results: In the case of clomipramine seven degradation products were separated and the corresponding m/z values were determined, while analyzing doxepine there have been separated eight degradation products, of which six were identified by their m/z values. The results obtained for clomipramine are in accordance with literature data, except for desmethyl-clomipramine, for which we could not find any reference. Conclusions: The m/z values indicate that the possible degradation products for clomipramine are imipramine, HO-imipramine, desmethyl-clomipramine and HO-imipramine-N-oxide. In the case of doxepine we could identify two possible photodegradation products, HO-doxepine and doxepine-N-oxide.