AstraZeneca’s cholesterol medicine Crestor’s patent protection is set to expire July 8, according to FDA standards, but the company has other plans for the drug.

Crestor is a statin designed and approved to treat high cholesterol in adults. AstraZeneca held exclusive patent rights to manufacture the drug under its brand name for the normal period after it was approved in 2003.

Turns out, Crestor can also be used to treat a rare disease called homozygous familial hypercholesterolemia that causes high cholesterol in children. So AstraZeneca is suing the FDA to continue its patent for another seven years so it can have exclusive rights to sell the drug for its original purpose in addition to its new purpose.  

An extended patent would protect AstraZeneca from competition from cheaper generics, but it would also impose the higher-priced name brand on the market for another seven years, even if for a different disease.

Martin A. Makary, MD, a professor of health policy at Johns Hopkins Medical School, told the New York Times the company is taking advantage of the rules’ technicalities.

“This represents a deviation from the intent of the Orphan Drug Act. It is now being used to dominate the market with retrofitted indications,” he said.

AstraZeneca said the lawsuit is intended to protect children with the disease from being prescribed a cheaper generic meant only for adult cholesterol management, labeled with the wrong dosage. (Generics wouldn’t be labeled with doses for kids, because Crestor was just approved to treat the condition in May and still holds those exclusivity rights.)

The petition filed against the FDA points out the “substantial safety and efficacy risks” inherent if the overall exclusivity protection is pulled.

Furthermore, the petition questions the FDA’s authority to regulate “orphan drugs” in this way.

Losing the patent could cost AstraZeneca billions of dollars, according to the Times. Crestor sales make them $5 billion($2.8 billion in the U.S.) of their annual $23.6 billion. It can cost up to $325 in certain pharmacies in the U.S.

Quartz pointed out the U.K. company has tried similar court measures to protect its drug Nexium from generic competition.