Fingerprint spectra for drug formulations using a DOSY filter: Pros and cons

It is often difficult to trace back drugs to the manufacturer, even though this can be important, especially when fake or low quality drugs are circulating. Drug formulations contain of the active pharmaceutical ingredient (API) and excipients and the finished products from different manufacturers usually differ. Hence, the characterization of the component composition is challenging. Here, we present an ¹H NMR method which is able to look at both by diffusion-ordered spectroscopy (DOSY). Using a DOSY filter, the signals of the solvents and the API can be attenuated, whereas the excipient signals are visible. This way, the overlap of the API and excipient signals is substantially reduced, which is advantageous when one of the components is present in excess.