title: Verification of the authenticity of drugs by means of NMR relaxometry-Viagra®as an example.
abstract: 1H spin-lattice Nuclear Magnetic Resonance (NMR) relaxometry, vibrational spectroscopy and Atomic Force Microscopy (AFM) have been applied to differentiate between original and counterfeit Viagra®. The relaxation studies have been performed in a frequency range covering four orders of magnitude, from 4kHz to 40MHz. It has been shown that for the counterfeit product the relaxation is bi-exponential in the whole frequency range, while for the original Viagra®the relaxation process is always single exponential. Thus, even a qualitative analysis of the relaxation data makes it possible to identify the falsified medicine. Moreover, it has been demonstrated that vibrational spectroscopy does not allow for differentiating between the products, while AFM studies are likely to lead one to deceptive conclusions regarding the originality of the medicine. Furthermore, a quantitative analysis of the relaxation data has been performed to describe in detail the relaxation properties of the original and falsified products.
authors.affiliation: Medical University of Silesia in Katowice, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Department of Basic Biomedical Science, Kasztanowa Street 3, Sosnowiec 41-200, Poland. Electronic address: swilczynski@sum.edu.pl.
authors.forename: S
authors.initials: S
authors.lastname: Wilczyńki
authors.affiliation: Medical University of Silesia in Katowice, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Department of Basic Biomedical Science, Kasztanowa Street 3, Sosnowiec 41-200, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Petelenz
authors.affiliation: University of Warmia and Mazury in Olsztyn, Department of Physics and Biophysics, Oczapowskiego 4, 10-719 Olsztyn, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Florek-Wojciechowska
authors.affiliation: University of Warmia and Mazury in Olsztyn, Faculty of Mathematics and Computer Science, Sloneczna 54, 10-710 Olsztyn, Poland.
authors.forename: S
authors.initials: S
authors.lastname: Kulesza
authors.affiliation: University of Warmia and Mazury in Olsztyn, Faculty of Mathematics and Computer Science, Sloneczna 54, 10-710 Olsztyn, Poland.
authors.forename: Sz
authors.initials: S
authors.lastname: Brym
authors.affiliation: Medical University of Silesia in Katowice, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Department of Basic Biomedical Science, Kasztanowa Street 3, Sosnowiec 41-200, Poland.
authors.forename: B
authors.initials: B
authors.lastname: Błońska-Fajfrowska
authors.affiliation: Medical University of Silesia in Katowice, School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Department of Basic Biomedical Science, Kasztanowa Street 3, Sosnowiec 41-200, Poland; University of Warmia and Mazury in Olsztyn, Department of Physics and Biophysics, Oczapowskiego 4, 10-719 Olsztyn, Poland. Electronic address: danuta.kruk@matman.uwm.edu.pl.
authors.forename: D
authors.initials: D
authors.lastname: Kruk
mesh_terms: D058110:Counterfeit Drugs / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D058986:Phosphodiesterase 5 Inhibitors / Q000009:adverse effects* / Q000592:standards; D000068677:Sildenafil Citrate / Q000032:analysis* / Q000592:standards; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods
chemical_list: D058110:Counterfeit Drugs; D058986:Phosphodiesterase 5 Inhibitors; D000068677:Sildenafil Citrate
keywords: Atomic Force Microscopy; Counterfeit drugs; NMR relaxometry; Viagra(®); Vibrational spectroscopy