If NDSRIs are not detected at end of stability, is small-molecule nitrosamine testing still required?

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Nitrosamine control in Metformin /Vildagliptin DP

I have a combination product containing (Metformin HCl & Vildagliptin). 1st Question: In confirmatory testing for nitrosamines in the product, I will consider both N-nitroso vildagliptin & N-nitroso vildagliptin amide determination as being NDSRIs. Shall I need to determine NDMA only or all the small molecules nitrosamine (NDMA, NDEA, NMPA, NDBA … etc) should be determined. 2nd Question: In controlling nitrosamine impurities in excipient, I shall focus on the key excipient (filler), as microcr…