The usefulness of simple X-ray powder diffraction analysis for counterfeit control--the Viagra example.

Counterfeit and illegally manufactured drugs become a very important problem all over the world, hence, a search for new fast, easy, reliable and not expensive methods of drugs screening is essential. We describe the use of X-ray powder diffraction method for the fast screening of tablets for counterfeit medicines identification. The original Viagra tablets and some counterfeit and/or imitations of Viagra were used as example. We demonstrate the application of diffraction method for discrimination of tablets coatings and for identification of differences in drug composition. The X-ray diffraction method turns out to be very fast and reliable for detecting counterfeits and imitation, and it correctly predicts the presence or absence of active substance and/or particular excipients.