Novo Nordisk A/S sued US pharmacies making and selling versions of semaglutide, the active ingredient in Wegovy, the company’s blockbuster weight-loss drug.

In lawsuits filed Thursday in Florida and Tennessee federal courts, Novo said that the compounding pharmacies violate state law by selling drugs that lack Food and Drug Administration approval and haven’t been sufficiently studied.

Novo’s US unit is seeking to protect Wegovy and Ozempic, the top-selling treatments that help patients shed pounds and have more than doubled the Danish drugmaker’s share price since the beginning of 2021. Last month, the company sued med spas and weight-loss clinics marketing compounded semaglutide, claiming trademark infringement.

“Ignoring drug-approval requirements provides defendant an unfair competitive advantage over pharmaceutical manufacturers like Novo Nordisk,” Novo said in the pharmacy suits. “Worse, it puts patients at risk by exposing them to drugs that have not been shown to be safe or effective.”

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In its lawsuits, Novo cites a 2012 fungal infection outbreak, related to a compounding center, that resulted in hundreds of diagnoses and dozens of deaths.

Thousands of compounding pharmacies in the US make custom versions of drugs for specific patients: for example, child-friendly liquid forms of solid drugs. The pharmacies are sometimes permitted to make and sell alternatives to FDA-approved drugs — often at far lower cost — if the agency says they’re in shortage, as it has with Wegovy and Ozempic, which also contains semaglutide.

However, the FDA doesn’t approve compounded products or have the same oversight it has with traditional prescription drugs. It has warned consumers about complaints of safety issues with compounded semaglutide, saying that “patients should not use a compounded drug if an approved drug is available to treat a patient.”

Novo sued DCA Pharmacy in federal court in Nashville, Tennessee. Suits against WellHealth Rx and TruLife Pharmacy were filed in a Jacksonville, Florida, federal court and Brooksville Rx was sued in Tampa. All the suits claim the pharmacies violated state consumer protection laws by selling drugs that weren’t approved by regulators.

The pharmacies didn’t immediately respond to a request for comment.

Analysts foresee Wegovy generating $4.2 billion in sales this year, and about $12.5 billion for Ozempic, a diabetes drug that’s often used for weight loss.

--With assistance from Bob Van Voris.

(Updates with detail in fifth paragraph.)