The use of dynamic thermal analysis to distinguish between genuine and counterfeit drugs.

WHO estimates that 10% of drugs are falsified. Economic and health factors arising from the use of counterfeit drugs lead to the development of new methods for distinguishing genuine medicines from falsified ones. The purpose of this study was to develop a new, fast, and inexpensive method to distinguish between original and fake drugs. 10 counterfeit Viagra(®) tablets were compared to 4 original pills (Pfizer). The drugs - both original and fake - were heated to 60°C and then the dynamics of their temperature changes at ambient conditions was tested using a thermal imaging camera. The time constants τ showing the dynamics of temperature changes for Viagra(®) and the falsified drug were determined. The thermokinetic parameters of drugs were determined in the temperature range of 60-22.2°C. Both original and counterfeit tablets had different time constants: 171.44 ± 4.62s and 182.71 ± 4.05 s, respectively. Differences in the dynamics of temperature changes as a function of time are particularly pronounced in the range of t+2 to t+7 min. The comparison of the time constants τ enables to distinguish between genuine and counterfeit drugs. The proposed new method which uses dynamic thermal analysis is an effective, cheap and fast technique to distinguish genuine drugs from counterfeit ones.