title: Comparison and combination of spectroscopic techniques for the detection of counterfeit medicines.
abstract: During this study, Fourier transform infrared spectroscopy (FT-IR), near infrared spectroscopy (NIR) and Raman spectroscopy were applied to 55 samples of counterfeit and imitations of Viagra and 39 samples of counterfeit and imitations of Cialis. The aim of the study was to investigate which of these techniques and associations of them were the best for discriminating genuine from counterfeit and imitation samples. Only the regions between 1800-400 cm(-1) and 7000-4000 cm(-1) were used for FT-IR and NIR spectroscopy respectively. Partial least square analysis has been used to allow the detection of counterfeit and imitation tablets. It is shown that for the Viagra samples, the best results were provided by a combination of FT-IR and NIR spectroscopy. On the other hand, the best results for the Cialis samples were provided by the combination of NIR and Raman spectroscopy (1400-1190 cm(-1)). These techniques not only permitted a clear discrimination between genuine and counterfeit or imitation samples but also the distinction of clusters among illegal samples. This might be interesting for forensic investigations by authorities.
authors.affiliation: Laboratory of Drug Analysis, Scientific Institute of Public Health, Rue Juliette Wytsmanstraat 14, 1050 Brussels, Belgium.
authors.forename: Pierre-Yves
authors.initials: PY
authors.lastname: Sacré
authors.forename: Eric
authors.initials: E
authors.lastname: Deconinck
authors.forename: Thomas
authors.initials: T
authors.lastname: De Beer
authors.forename: Patricia
authors.initials: P
authors.lastname: Courselle
authors.forename: Roy
authors.initials: R
authors.lastname: Vancauwenberghe
authors.forename: Patrice
authors.initials: P
authors.lastname: Chiap
authors.forename: Jacques
authors.initials: J
authors.lastname: Crommen
authors.forename: Jacques O
authors.initials: JO
authors.lastname: De Beer
mesh_terms: D002243:Carbolines / Q000032:analysis*; D016018:Least-Squares Analysis; D010726:Phosphodiesterase Inhibitors / Q000032:analysis*; D010879:Piperazines / Q000032:analysis*; D025341:Principal Component Analysis; D011687:Purines / Q000032:analysis; D000068677:Sildenafil Citrate; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D019265:Spectroscopy, Near-Infrared / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013450:Sulfones / Q000032:analysis*; D000068581:Tadalafil
chemical_list: D002243:Carbolines; D010726:Phosphodiesterase Inhibitors; D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068581:Tadalafil; D000068677:Sildenafil Citrate