TY - JOUR T1 - Screening of synthetic PDE-5 inhibitors and their analogues as adulterants: analytical techniques and challenges. AU - Patel,Dhavalkumar Narendrabhai, AU - Li,Lin, AU - Kee,Chee-Leong, AU - Ge,Xiaowei, AU - Low,Min-Yong, AU - Koh,Hwee-Ling, Y1 - 2013/05/06/ PY - 2013/03/13/received PY - 2013/04/25/revised PY - 2013/04/26/accepted PY - 2013/6/1/entrez PY - 2013/6/1/pubmed PY - 2014/8/30/medline KW - (1)H NMR KW - (13)C NMR KW - 1 dimensional nuclear magnetic resonance KW - 1D NMR KW - 2 dimensional nuclear magnetic resonance KW - 2D NMR KW - Analytical techniques KW - CART KW - CE-MS KW - CID KW - CNLS KW - COSY KW - Challenges KW - D-PLS KW - DAD KW - DCBI KW - DEPT KW - DOSY–NMR KW - Designer analogues KW - ED KW - ESI KW - EU KW - European Union KW - FT-ICR-MS KW - FT-IR KW - FTIR-ATR KW - Fourier transform ion cyclotron resonance-mass spectrometry KW - Fourier transformed infrared KW - Fourier transformed infrared attenuated total reflectance KW - GC–MS KW - HMBC KW - HMQC KW - HPLC KW - HPLC-DCBI–MS/MS KW - HPTLC KW - HRMS KW - HSA KW - Health Sciences Authority Singapore KW - IDA KW - IMS KW - LC–ESI-MS(n) KW - LC–FT-ICR-MS KW - LC–LTQ Orbitrap XL FTMS KW - LC–MS KW - LC–TIS-MS KW - LC–TOF-MS KW - LC–q-TOF-MS/MS KW - MDMA KW - MRM KW - MS KW - MS(n) KW - MS/MS KW - NDA KW - NIR KW - NMR KW - NOE KW - NOESY KW - New Drug Application KW - PCA KW - PDE-5 KW - PDE-5 inhibitors KW - PIS KW - PP KW - PREC KW - SIM KW - SIMCA KW - SRM KW - SVM KW - Screening for adulterants KW - THMPD KW - TIS KW - TLC KW - TOF KW - TQ-LIT KW - Traditional Herbal Medicinal Products Directive KW - UHPLC KW - USFDA KW - UV KW - United States Food and Drug Administration KW - X-ray diffraction KW - X-ray fluorescence KW - XRD KW - XRF KW - capillary electrophoresis–mass spectrometry KW - carbon-13-nuclear magnetic resonance KW - classification and regression trees KW - collision induced dissociation KW - constant neutral loss scan KW - correlation spectroscopy KW - desorption corona beam ionization KW - diffusion ordered spectroscopy–nuclear magnetic resonance KW - diode array detector KW - discriminant partial least squares KW - distortionless enhancement by polarization transfer KW - electrospray ionization KW - erectile dysfunction KW - gas chromatography–mass spectrometry KW - heteronuclear multiple-bond correlation spectroscopy KW - heteronuclear multiple-quantum correlation spectroscopy KW - high performance liquid chromatography KW - high performance liquid chromatography-desorption corona beam ionization–tandem mass spectrometry KW - high performance thin layer chromatography KW - high resolution mass spectrometry KW - information dependent acquisition KW - ion mobility spectroscopy KW - liquid chromatography mass-spectrometry KW - liquid chromatography-Fourier transform ion cyclotron resonance-mass spectrometry KW - liquid chromatography–electrospray ionization-tandem mass spectrometer KW - liquid chromatography–linear ion orbitrap XL Fourier transform mass spectrometry KW - liquid chromatography–quadrupole-time-of-flight-tandem mass spectrometry KW - liquid chromatography–time of flight-mass spectrometry KW - liquid chromatography–turbo ion spray mass spectrometry KW - mass spectrometry KW - methylenedioxymethamphetamine KW - multi-stage mass spectrometry KW - multiple reaction monitoring KW - near infrared KW - nuclear Overhauser effect KW - nuclear Overhauser effect spectroscopy KW - nuclear magnetic resonance KW - phosphodiesterase type 5 enzyme KW - precursor ion scanning KW - principal component analysis KW - product ion scanning KW - projection pursuit KW - proton nuclear magnetic resonance KW - selected ion monitoring KW - selected reaction monitoring KW - soft independent modelling by class analogy KW - support vector machines KW - tandem mass spectrometry KW - thin layer chromatography KW - time of flight KW - triple quadruple linear ion trap KW - turbo ion spray KW - ultra high performance liquid chromatography KW - ultraviolet SP - 176 EP - 90 JF - Journal of pharmaceutical and biomedical analysis JO - J Pharm Biomed Anal VL - 87 N2 - The popularity of phosphodiesterase type 5 (PDE-5) enzyme inhibitors for the treatment of erectile dysfunction has led to the increase in prevalence of illicit sexual performance enhancement products. PDE-5 inhibitors, namely sildenafil, tadalafil and vardenafil, and their unapproved designer analogues are being increasingly used as adulterants in the herbal products and health supplements marketed for sexual performance enhancement. To date, more than 50 unapproved analogues of prescription PDE-5 inhibitors were found as adulterants in the literature. To avoid detection of such adulteration by standard screening protocols, the perpetrators of such illegal products are investing time and resources to synthesize exotic analogues and devise novel means for adulteration. A comprehensive review of conventional and advance analytical techniques to detect and characterize the adulterants is presented. The rapid identification and structural elucidation of unknown analogues as adulterants is greatly enhanced by the wide myriad of analytical techniques employed, including high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), liquid chromatography mass-spectrometry (LC-MS), nuclear magnetic resonance (NMR) spectroscopy, vibrational spectroscopy, liquid chromatography-Fourier transform ion cyclotron resonance-mass spectrometry (LC-FT-ICR-MS), liquid chromatograph-hybrid triple quadrupole linear ion trap mass spectrometer with information dependent acquisition, ultra high performance liquid chromatography-time of flight-mass spectrometry (UHPLC-TOF-MS), ion mobility spectroscopy (IMS) and immunoassay methods. The many challenges in detecting and characterizing such adulterants, and the need for concerted effort to curb adulteration in order to safe guard public safety and interest are discussed. SN - 1873-264X UR - https://www.unboundmedicine.com/medline/citation/23721687/Screening_of_synthetic_PDE_5_inhibitors_and_their_analogues_as_adulterants:_analytical_techniques_and_challenges_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0731-7085(13)00191-X DB - PRIME DP - Unbound Medicine ER -