Losartan azide (left) and AZBT (right), two azido process impurities detected in sartans. Losartan azide occurs exclusively during manufacture of losartan, while AZBT can be found in several drugs in the class.
In April 2021, the European Directorate for the Quality of Medicines (EDQM) warned of the risk of contamination with non-nitrosamine impurities (specifically, azido compounds) in tetrazole-containing sartans. In September 2021, the EDQM announced that investigations had revealed a novel azido contaminant which occurs only in losartan (losartan azide or losartan azido impurity) and which was found to be mutagenic on Ames testing.
