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.

With an estimated 2 million people in the United States taking copycat vers | A compounding industry group has sued the FDA, claiming its action to remove Eli Lilly’s Mounjaro and Zepbound from its drug shortage list is a “reckless and arbitrary decision—lacking any semblance of lawful process.

The two-year shortage of Eli Lilly’s blockbuster weight-loss and diabetes drugs is over, the U.S. Food and Drug Administration announced Wednesday.

Eli Lilly shares have soared thanks to excitement about the company's position in the weight loss drug market.