Identification of phototransformation products of sildenafil (Viagra) and its N‐demethylated human metabolite under simulated sunlight

Journal of Mass Spectrometry - Tập 47 Số 6 - Trang 701-711 - 2012
Peter Eichhorn1, Sandra Pérez1, Jaume Aceña1, Piero R. Gardinali2, José Luı́s Abad3, ‪Damià Barceló4,1,5
1IDAEA-CSIC, Department of Environmental Chemistry, Jordi Girona 18-26, Barcelona 08034, Spain
2Florida International University; 11200 SW 8th Street Miami Florida 33199-0001 USA
3IQAC-CSIC; Department of Biomedicinal Chemistry; Jordi Girona 18-26; Barcelona; 08034; Spain
4Catalan Institute of Water Research, c/Emili Grahit, 101, Edifici H2O Parc Científic i Tecnològic de la Universitat de Girona Girona 17003 Spain
5King Saud University BOX 2455 Riyadh 11451 Saudi Arabia

Tóm tắt

Recent publications on pharmaceutical monitoring are increasingly covering the field of illicit drugs and lately the forensic evaluation of designing illegal analogs of lifestyle drugs like the phosphodiesterase type 5 (PDE‐5) inhibitors Viagra (sildenafil), Levitra (vardenafil) and Cialis (tadalafil). Recently, the presence of all three erectile dysfunction treatment drugs has been reported in wastewaters at very low concentrations. In the environment, contaminants undergo various physical or chemical processes classified into abiotic (photolysis, hydrolysis) and biotic (biodegradation) reactions. Thus, changes in the chemical structure lead to the formation of new transformation products, which may persist in the environment or be further degraded. This study describes the photolysis of sildenafil (SDF) and its human metabolite N‐demethylsildenafil (DM‐SDF) under simulated solar radiation (Xenon lamp). Following chromatographic separation of the irradiated samples, eight photoproducts in the SDF samples and six photoproducts for DM‐SDF were detected and characterized. The combination of ultra performance liquid chromatography‐electrospray ionization‐quadrupole time‐of‐flight‐mass spectrometry (UPLC‐ESI‐QToF‐MS), liquid chromatography‐atmospheric pressure chemical ionization‐triple quadrupole mass spectrometry (LC‐APCI‐QqQ‐MS) and hydrogen/deuterium‐exchange experiments allowed to propose plausible chemical structures for the photoproducts, taking into account the characteristic fragmentation patterns and the accurate mass measurements. These mass spectral data provided sound evidence for the susceptibility of the piperazine ring toward photodegradation. A gradual breakdown of this heterocyclic structure gave rise to a series of products, which in part were identical for SDF and DM‐SDF. The sulfonic acid, as the formal product of sulfonamide hydrolysis, was identified as key intermediate in the photolysis pathway. In both drug/metabolite molecules, phototransformation processes taking place beyond the sulfonamide group were deemed to be of minor relevance. Copyright © 2012 John Wiley & Sons, Ltd.

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Thông tin xuất bản

Journal of Mass Spectrometry

Tập 47 Số 6

701-711

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