The U.S. Food and Drug Administration (FDA) recently sent several warning letters to manufacturers of over-the-counter supplement products that include AMP citrate, a stimulant also known as DMBA. The companies were ordered to halt sales because the agency said it was not aware of evidence establishing AMP citrate as safe to use as a dietary ingredient. The companies that received letters include 1ViZN LLC, Beta Labs, Blackstone Labs LLC, Brand New Energy LLC, Core Nutritionals, Genomyx LLC, Iron Forged Nutrition, Nutrex Research LLC, Powder City LLC, RPM Nutrition LLC, and VPX Sports. FDA has recently targeted stimulant ingredients in weight-loss and workout supplements, including warning letters sent in April 2015 over BMPEA.