Falsification of active pharmaceutical ingredients (APIs) has been recognized as an important health issue since a series of health scares involving large numbers of casualties happened when altered APIs escaped detection in routine analytical testing. Any form of tampering the content or information about the content might affect the quality of the API, the finished product and therefore constitutes a direct threat to the health of patients (Position paper for OMCLs on API surveillance, EDQM). The conventional analytical approach often fails to detect falsification since the quality and quantity of the API might be within the current standards. Instead, methods that allow distinction of API samples, according to their source are needed.

Within the General European Official Medicines Control Laboratory (OMCL) Network (GEON) different initiatives were taken to augment the analysis and market surveillance of APIs used by the different manufacturers. Despite the efforts, API testing within the network is limited, compared to the surveillance of finished products. To tackle the issue of falsified API detection the API-working group (API-WG) of the GEON organizes atypical market surveillance studies (MSS), where an MSS (analysis according to the Ph. Eur.) is combined with a fingerprint study (MSSFP). An MSS, according to Ph. Eur. only gives an indication of the quality of the product on some distinct parameters, often chosen based on the manufacturing process. A MSSFP study allows to obtain a global image of the sample, to compare to batches of the (presumed) manufacturer and/or to data of fingerprint studies performed in the past. (Deconinck et al., 2022, Rebiere et al., 2022).

The aim of the paper is to highlight the challenges and pitfalls in detecting falsified APIs and to give an insight in the work of the GEONs API-WG with a special focus on the MSSFP studies. A summary is given of the MSSFP study on sildenafil citrate and this for the set-up and the obtained results.