The nitrosamine saga: how one impurity rewrote global quality rules

In June 2018 a manufacturer of valsartan told European regulators that its active ingredient contained N-nitrosodimethylamine (NDMA), a probable human carcinogen. The source was Chinese API maker Zhejiang Huahai Pharmaceutical (SHA: 600521). Within weeks, generic versions of the blood pressure drug were being recalled across Europe and the USA, and regulators began asking whether the problem was confined to one molecule.

It was not. The same class of impurity was subsequently found in losartan and irbesartan, then in ranitidine, metformin and pioglitazone. In 2020 the US FDA requested the withdrawal of all ranitidine products, including Zantac (ranitidine), and the EU suspended the marketing authorizations for the whole class. A contamination incident had become a permanent quality obligation.