Detection Method of Falsified Medicines by Using a Low-Cost Raman Scattering Spectrometer Combined with Soft Independent Modeling of Class Analogy and Partial Least Squares Discriminant Analysis.

There are many reports of falsified medicines that may cause harm to patients. A rapid and simple method of identifying falsified medicines that could be used in the field is required. Although Raman scattering spectroscopy has become popular as a non-destructive analysis, few validation experiments on falsified medicines that are actually distributed on the market have been conducted. In this study, we validated a discriminant analysis using an ultra-compact, portable, and low-cost Raman scattering spectrometer combined with multivariate analysis. The medicines were three types of erectile dysfunction therapeutic tablet and one type of antifungal tablet: tadalafil (Cialis), vardenafil hydrochloride (Levitra), sildenafil citrate (Viagra), and fluconazole (Diflucan), which is sometimes advertised as female Viagra. For each medicine, the authentic standard product and products obtained by personal import via the internet (genuine or falsified) were used. Discriminant analyses were performed on the Raman spectra combined with soft independent modeling of class analogy (SIMCA) and partial least squares discriminant analysis (PLS-DA). It was possible to identify all falsified samples by SIMCA using the standard product model for all four products. Using the PLS-DA using the PLS models of the four standard products, falsified Levitra and Diflucan samples were classified correctly, although some falsified Cialis and all Viagra samples also belonged to the standard class. In this study, SIMCA might be more suitable than PLS-DA for identifying falsified medicines. A spectroscopic module that combines the low-cost Raman scattering spectroscopy with SIMCA might contribute to the rapid identification of falsified medicines in the field.

Falsified vardenafil tablets available online.

It is often reported that falsified medicines have harmful effects on patients both Japan and abroad. In this study, we purchased vardenafil tablets on the internet and investigated their quality and authenticity using visual observations, authenticity investigations, non-destructive tests (handheld NIR and Raman spectroscopy), and quality analyses (active ingredient content and tablet dissolution rate). We used genuine 20-mg Levitra tablets that were sold in Japan and tablets from Bayer AG (Germany) as controls. In April 2015, we obtained 28 samples from 15 websites on the internet. Our authenticity investigations revealed that 11 (40%) were genuine products and 17 (60%) were falsified products. Handheld NIR and Raman results revealed that the falsified products had different spectra to the genuine products. Principal component analysis of the NIR and Raman spectra showed variation among the falsified products. The 11 genuine products were of good quality, and the 17 falsified products were of poor quality. The falsified products contained sildenafil (the active ingredient of Viagra) or tadalafil (the active ingredient of Cialis) instead of vardenafil. Our results show that falsified Vardenafil tablets are sold on the internet and that it is important to prevent illegal internet sales and increase consumer awareness of the presence of falsified medicines.