The U.S. Food and Drug Administration (FDA) has announced that over half a million bottles of the blood pressure medication prazosin hydrochloride have been recalled due to concerns over a potential carcinogenic contaminant.

Teva Pharmaceuticals USA, based in New Jersey, along with the drug distributor Amerisource Health Services, initiated voluntary recalls across the nation this month. The recall affects more than 580,000 bottles of prazosin capsules in various strengths, as reported by the FDA.

Prazosin is commonly prescribed to relax blood vessels, aiding in the reduction of blood pressure. It is also occasionally used to treat nightmares and other sleep disturbances associated with post-traumatic stress disorder (PTSD).

The FDA’s online enforcement notices have categorized the affected medication batches under a Class II recall, citing that some of these prazosin products might contain nitrosamine impurities, which are chemicals considered to have potential cancer-causing properties.

N-nitrosamine impurities, according to the FDA, are a category of chemicals that can potentially cause cancer. They may develop during the manufacturing or storage processes of a drug.