An industry group representing companies that manufactured the copycat versions of Eli Lilly's (NYSE:LLY) highly popular weight loss therapy tirzepatide sued the U.S. FDA on Monday over the agency's decision to declare an end to the drug's shortage last week.

The popularity of GLP-1 weight loss drugs has soared, which had created a shortage among many of the drugs, including Eli Lilly 's (NYSE: LLY) popular Mounjaro and Zepbound. However, the U.S. Food and Drug Administration (FDA) recently removed both drugs from its shortage list, indicating that supply can now keep up with current demand.

FDA faces legal action after removing Tirzepatide from the shortage list without following required procedures, sparking concerns over patient access to the compounded diabetes and obesity treatment.