title: Directional reflectance analysis for identifying counterfeit drugs: Preliminary study.
abstract: The WHO estimates that up to 10% of drugs on the market may be counterfeit. In order to prevent intensification of the phenomenon of drug counterfeiting, the methods for distinguishing genuine medicines from fake ones need to be developed. The aim of this study was to try to develop simple, reproducible and inexpensive method for distinguishing between original and counterfeit medicines based on the measurement of directional reflectance. The directional reflectance of 6 original Viagra(®) tablets (Pfizer) and 24 (4 different batches) counterfeit tablets (imitating Viagra(®)) was examined in six spectral bands: from 0.9 to 1.1 μm, from 1.9 to 2.6 μm, from 3.0 to 4.0 μm, from 3.0 to 5.0 μm, from 4.0 to 5.0 μm, from 8.0 to 12.0 μm, and for two angles of incidence, 20° and 60°. Directional hemispherical reflectometer was applied to measure directional reflectance. Significant statistical differences between the directional reflectance of the original Viagra(®) and counterfeit tablets were registered. Any difference in the value of directional reflectance for any spectral band or angle of incidence identifies the drug as a fake one. The proposed method of directional reflectance analysis enables to differentiate between the real Viagra(®) and fake tablets. Directional reflectance analysis is a fast (measurement time under 5s), cheap and reproducible method which does not require expensive equipment or specialized laboratory staff. It also seems to be an effective method, however, the effectiveness will be assessed after the extension of research.
authors.affiliation: School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia in Katowice, Department of Basic Biomedical Science, Kasztanowa Street 3, Sosnowiec 41 200, Poland. Electronic address: swilczynski@sum.edu.pl.
authors.forename: Sławomir
authors.initials: S
authors.lastname: Wilczyński
authors.affiliation: Department of Biomedical Computer Systems, University of Silesia, Faculty of Computer Science and Materials Science, Institute of Computer Science, Będzińska Street 39, Sosnowiec 41 200, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Koprowski
authors.affiliation: School of Pharmacy with the Division of Laboratory Medicine in Sosnowiec, Medical University of Silesia in Katowice, Department of Basic Biomedical Science, Kasztanowa Street 3, Sosnowiec 41 200, Poland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Błońska-Fajfrowska
mesh_terms: D058110:Counterfeit Drugs; D014944:World Health Organization
chemical_list: D058110:Counterfeit Drugs
keywords: Counterfeit medicines; Directional reflectance; Screening method; Viagra(®)