Ozempic maker Novo Nordisk (NVO) is asking the U.S. Food and Drug Administration (FDA) to prohibit compounding pharmacies from making off-brand versions of semaglutide, the active ingredient in its blockbuster weight loss and diabetes medications.

Novo Nordisk has asked the FDA to block production of compounded copies of Ozempic, arguing that it’s too difficult to do safely. It’s the latest escalation in a brewing war between pharmaceutical companies and compounders.

Novo Nordisk wants the Food and Drug Administration (FDA) to prevent compounding pharmacies from manufacturing their own versions of the company’s popular weight loss drug Wegovy and diabetes treatment Ozempic,

The agency posted documents this week that the drugmaker had requested the drug be placed on the FDA's "Demonstrable Difficulties for Compounding Lists."