"That said, any presence of such impurities in drug products is not acceptable", FDA Commissioner Scott Gottlieb said in the statement.
This is the first hypertension medication found to contain NMBA, but a handful of other recalls at the end of 2018 resulted from the potential contamination of N-Nitrosodimethylamine (NDMA) or N-nitrosodiethylamine (NDEA)-two other potential carcinogens.
The recalled losartan potassium tablets made by Hetero Labs and distributed by Camber Pharmaceuticals contain the impurity, N-Nitroso-N-methyl-4-aminobutyric acid (NMBA). Its presence in these medicines' active ingredient, manufactured in this case by India-based Hetero Labs Limited, is considered an impurity.
"FDA scientists have developed novel and sophisticated testing methods specifically created to detect and measure N-Nitrosodimethylamine (NDMA) and N-Nitrosodiethylamine (NDEA) impurities in [angiotensin II receptor blocker (ARB)] medicines", Gottlieb wrote.
The medicine is used to treat high blood pressure and congestive heart failure. A full record of recalled drugs is offered from the FDA.
The agency and companies are testing all ARBs for impurities.
The FDA also said it is working to develop testing methods to detect other cancer-causing impurities. Zhejiang Huahai has said it has been in close contact with the FDA since the recall began.
Regarding how the recall has affected patients and pharmacists, "most patients have to come in and get their medications changed out" to lots of medication that have not been affected, Freeman said. The company also makes losartan for other Indian drugmakers, including Torrent Pharmaceuticals Ltd. and Macleods Pharmaceuticals Ltd., that has been recalled for containing NDEA.
The FDA says no one has reported any adverse effects from the drug and patients should speak with their doctor to discuss the recall before they stop taking the drug.
From a community pharmacy perspective, this recall has been hard because many pharmacies don't keep the lot numbers of medications after they're dispensed, Freeman said: "That information is not tracked effectively".