Analysis of counterfeit Cialis® tablets using Raman microscopy and multivariate curve resolution

Counterfeit medicines have become a serious global problem. Consequently, analytical and pharmaceutical scientists have been active in developing and applying new methodologies to detect and analyze counterfeit medicines. Vibrational spectroscopy combined with chemometric methods is becoming a popular choice in this area of research. In this study, Raman microscopy was used to collect chemical images of counterfeit tadalafil tablets and multivariate curve resolution (MCR) was used to analyze the Raman spectra and reveal the identities of the excipients and active pharmaceutical ingredients (API) in each tablet. Resolved counterfeit tablet spectra were compared to the resolved genuine tablet spectra. Both similarities and dissimilarities were revealed by the analysis in terms of the identity of the excipients, the quantity of the API, and the distribution of the components. It was concluded that Raman microscopy combined with MCR is a powerful method to detect and analyze counterfeit tablets. (C) 2012 Elsevier B.V. All rights reserved.