New test successful in finding fake medicines

A spectroscopy technology has proved effective in sorting genuine medicinal products from counterfeits.

The application of the method - called Attenuated Total Reflection Fourier-Transform infrared spectroscopy (ATR-FTIR) - is described in the Journal of Pharmaceutical and Biomedical Analysis and could be useful for screening of counterfeit medicines since it is easy to use and little sample preparation is required.

The study from researchers in Belgium used a combination of ATR-FTIR and chemometrics to discriminate and classify counterfeit medicines.

A sample set, containing 209 samples in total, was analysed using ATR-FTIR and the obtained spectra were used as fingerprints in the chemometric data-analysis.

This included: Principal Component Analysis (PCA), k-Nearest Neighbours (k-NN), Classification and Regression Trees (CART) and Soft Independent Modelling of Class Analogy (SIMCA).

These samples include some of the most counterfeited medicines in the world, including Pfizer's Viagra (sildenafil) and Eli Lilly's Cialis (tadalafil) samples, generic products of Viagra, counterfeit samples containing sildenafil, tadalafil or both, and placebo samples.

First it was verified whether the mentioned techniques are capable to distinguish samples containing different active pharmaceutical ingredients (APIs).

PCA showed a clear tendency of discrimination based on the API present; k-NN, CART and SIMCA were capable to create suitable prediction models based on the presence of different APIs.

However, k-NN performs the least while SIMCA performs the best. Second, it was tested whether these three models could be expanded to discriminate between genuine and counterfeit samples as well. k-NN was not able to make the desired discrimination and therefore it was not useful.

CART performed better but also this model was less suited. SIMCA, on the other hand, resulted in a model with a 100% correct discrimination between genuine and counterfeit drugs.

The paper says this is an important tool as counterfeit medicines "pose a huge threat to public health worldwide", with both developing and industrialised countries exposed to pharmaceutical counterfeiting.

This can cause serious harm to patients, as the drugs may contain no active ingredient, or one harmful to the, and it can also cause economic harm by having payers spend money on medicines that will not work.

The authors conclude: "High amounts of counterfeit medicines enter the European market and detection of such pharmaceuticals at customs is not always simple due to misleading packaging.

"Therefore easy to use equipment and techniques to perform an initial screening of these samples are needed. For this purpose Attenuated Total Reflection Fourier-Transform infrared spectroscopy (ATR-FTIR) is an interesting technique since it is user-friendly and little sample preparation is needed."