The saga of tainted valsartan has taken another turn with an online pharmacy that tests its medications before dispensing them finding yet another probable carcinogen in lots of the blood pressure medication from multiple manufacturers. The pharmacy filed a citizen petition asking the US FDA to tighten its globally harmonized limit for the residual solvent.

US FDA officials told manufacturers to beware of using reused solvents and catalysts to avoid carcinogenic impurities such as nitrosamines from leaching into valsartan and other ARBs used to treat high blood pressure. FDA has identified 40 nitrosamine-free ARBs to provide alternatives to patients and health care providers experiencing shortages caused by recent recalls of these products.

European authorities are examining how a manufacturing process change six years ago may have introduced a probable carcinogen into Zhejiang Huahai’s valsartan API that was only recently detected. They hope to learn how the firm could reduce or eliminate the impurity.