Solid state C NMR spectroscopy as a tool for identification of counterfeit Viagra tablets and guide for develop new identification approach of falsified product.

Counterfeit drugs are a global problem that is directly related to the safety and effectiveness of pharmacotherapy. The black market for counterfeit products is constantly growing and related to the wide availability through online shopping. Therefore, there is a constant need to develop analytical methods that would allow for the unambiguous identification of counterfeit products from the original ones.

Comparison of the analytical methods (solid state NMR, FT-IR, PXRD) in the analysis of the solid drug forms with low concentration of an active ingredient - 17-β-estradiol case.

The application of various techniques (FT-IR, PXRD, ssNMR) in the analysis of solid dosage forms with low concentration of an API (17-β-estradiol hemihydrate, EBHH) was tested. PXRD analysis of Estrofem Mite tablets (EMT) confirmed the presence of the main crystalline excipient, α-lactose monohydrate. In the PXRD pattern of EMT the strong background from polycrystalline excipients, i.