Evaluation of the residual solvent content of counterfeit tablets and capsules

in Journal of Pharmaceutical & Biomedical Analysis (2013), 81-82

A group of counterfeit samples of Viagra® and Cialis® were screened for their residual solvent content and compared to the content of the genuine products. It was observed that all counterfeit samples had ... [more ▼]

A group of counterfeit samples of Viagra® and Cialis® were screened for their residual solvent content and compared to the content of the genuine products. It was observed that all counterfeit samples had higher residual solvent contents compared to the genuine products. A more diverse range of residual solvents was found as well as higher concentrations. In general these concentrations did not exceed the international imposed maximum limits. Only in a few samples the limits were exceeded. A Projection Pursuit analysis revealed clusters of samples with similar residual solvent content, possibly enabling some future perspectives in forensic research. [less ▲]

Analytical strategies for the detection of counterfeit erectile dysfunction drugs.

in Wang, Perry; Wertheimer, Albert (Eds.) Counterfeit Medicines Volume II: Detection, Identification and Analysis (2012)

Among all classes of drugs, the type 5 phosphodiesterase inhibitors (PDE5-i) (sildenafil, vardenafil and tadalafil) are the most counterfeited and copied in industrialized countries. This is why it is ... [more ▼]

Among all classes of drugs, the type 5 phosphodiesterase inhibitors (PDE5-i) (sildenafil, vardenafil and tadalafil) are the most counterfeited and copied in industrialized countries. This is why it is very important for regulatory agencies to have a panel of analytical methods to analyse these drugs and to be able to detect counterfeit or substandard medicines. During this chapter, several analytical techniques will be described and discussed. Among spectroscopic techniques, Raman, NIR, FT-IR and chemical imaging techniques will be envisaged. Their ability to detect counterfeits and predict if a new sample is genuine or not will be presented. Other techniques such as XRay powder diffraction and NMR spectroscopies will be briefly presented. Chromatographic impurity fingerprints will be considered and described for the analysis of suspect samples of Cialis® and Viagra®. Once again, the possibility to predict the authenticity of a new sample by the mean of this technique is envisaged. Finally, a MS-compatible UHPLC-UV method for the analysis of the three authorised PDE5-i and some of their analogues will be shortly described. This technique has been validated using spiked placebo samples in a vegetal matrix representing a suspect sample with a complex matrix. As a conclusion, a generic strategy for the detection and quality evaluation of counterfeit drugs will be presented. [less ▲]

Classification Trees based on infrared spectroscopic data to discriminate between genuine and counterfeit medicines.

Poster (2012)

Due to the extension of the internet, counterfeit drugs represent a growing threat for public health in the developing countries but also more and more in the industrial world. In literature several ... [more ▼]

Due to the extension of the internet, counterfeit drugs represent a growing threat for public health in the developing countries but also more and more in the industrial world. In literature several analytical techniques were applied in order to discriminate between genuine and counterfeit medecines. One thing all these techniques have in common is that they generate a huge amount of data, which is often difficult to interpret in order to see differences between the different samples and to determine the cause of the differences. The majority of the authors make use of explorative chemometric tools to visualise the differences in the data obtained for the different samples. Even if some of the applied methods could be able to give a model with predictive ability, only a few authors created a model able to predict if a sample is counterfeit or not. Classification trees built with the Classification And Regression Tree algorithm were evaluated for modelling infrared spectroscopic data in order to discriminate between genuine and counterfeit drug samples and to classify counterfeit samples in different classes following the RIVM classification system. Models were built for two data sets consisting of the Fourrier Transformed Infrared spectra, the Near Infrared spectra and the Raman spectra for genuine and counterfeit samples of respectively Viagra® and Cialis®. Easy interpretable models were obtained for both models. The models were validated for their descriptive and predictive properties. The predictive properties were evaluated using both cross validation as an external validation set. The obtained models for both data sets showed a 100% correct classification for the discrimination between genuine and counterfeit samples and 83.3% and 100% correct classification for the counterfeit samples for the Viagra® and the Cialis® data set respectively. [less ▲]

Classification trees based on infrared spectroscopic data to discriminate between genuine and counterfeit medecines

Conference (2011, September 23)

Classification trees built with the Classification And Regression Tree algorithm were evaluated for modelling infrared spectroscopic data in order to discriminate between genuine and counterfeit drug ... [more ▼]

Classification trees built with the Classification And Regression Tree algorithm were evaluated for modelling infrared spectroscopic data in order to discriminate between genuine and counterfeit drug samples and to classify counterfeit samples in different classes following the RIVM classification system. Models were built for two data sets consisting of the Fourier Transform Infrared spectra, the Near Infrared spectra and the Raman spectra for genuine and counterfeit samples of respectively Viagra® and Cialis®. Easy interpretable models were obtained for both models. The models were validated for their descriptive and predictive properties. The predictive properties were evaluated using both cross validation as an external validation set. The obtained models for both data sets showed a 100% correct classification for the discrimination between genuine and counterfeit samples and 83.3% and 100% correct classification for the counterfeit samples for the Viagra® and the Cialis® data set respectively. [less ▲]

Impurity fingerprints for the identification of counterfeit medicines - a feasibility study

Poster (2011, June 22)

Detection of counterfeit Viagra by Raman microspectroscopy imaging and multivariate analysis

Conference (2011, May 13)

Development and validation of a ultra-high-performance liquid chromatography-UV method for the detection and quantification of erectile dysfunction drugs and some of their analogues found in counterfeit medicines

in Journal of Chromatography. A (2011), 1218

Pharmaceutical counterfeiting is a permanently growing problem. Control laboratories are constantly analysing counterfeit medicines. In industrialised countries, one of the main counterfeited class of ... [more ▼]

Pharmaceutical counterfeiting is a permanently growing problem. Control laboratories are constantly analysing counterfeit medicines. In industrialised countries, one of the main counterfeited class of medicines are erectile dysfunction drugs. This paper describes the development and validation of a fast method to detect and quantify the three authorised phosphodiesterase type 5 inhibitors and five analogues. The method is based on the use of a sub-2 microns polar-embedded column with a gradient using acetonitrile as organic modifier and 10 mM ammonium formate buffer (pH 3.5) as aqueous component of the mobile phase. The separation was achieved in less than 4.5 min. The method has also been compared to the registered HPLC method for the assay of Viagra® which was considered as the reference method. The method is also compatible with on-line coupling mass spectrometry and will significantly reduce analysis times and solvent consumption. [less ▲]

Detection of counterfeit Viagra® by Raman Microspectroscopy imaging and multivariate analysis.

in Journal of Pharmaceutical & Biomedical Analysis (2011), 56

Comparison and combination of spectroscopic techniques for the detection of counterfeit medicines

in Journal of Pharmaceutical & Biomedical Analysis (2010), 53

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 ... [more ▼]

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 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. [less ▲]

Determination of uncertainty in analytical measurements: Collaborative study of the analysis of phenoxymethylpenicillin

Poster (2002, April)