The FDA also wrote that although the law restricts combination drugs that are "essentially copies of commercial drugs," "we do not consider a drug to be commercially available when it appears on the FDA's drug shortage list." At this time, we note that semaglutide for sale (WEGOVY) injection is on the Drug shortage list in the new label or window list from the U.S. Food and Drug Administration."

Despite the potential vulnerability, Novo Nordisk holds a number of patents protecting its semaglutide for sale drugs, including diabetes drug Ozenpic, and the company said in an email to MedPage Today that entities selling products containing semaglutide "may have infringed Novo Nordisk's intellectual property rights and/or violated applicable laws." Novo Nordisk will take such action as it deems necessary and appropriate to protect its intellectual property rights."

Doctors also found it baffling that compounding pharmacies were able to obtain the patented substance.

"No one knows how they got it," said Nadolsky of the compounding pharmacy. "Who did it? Novo didn't give it to them. They are people with molecular rights, so how could anyone get semaglutide for sale?"

Jacob Sherkow, JD, professor of law and medicine at the Illinois College of Medicine, told Medical Today that most of the active pharmaceutical ingredients used in compounding pharmacies are not actually synthesized at compounding pharmacies.

Sherkow said the substances are bought from countries outside the United States where chemical manufacturing is cheaper, such as China on the new label or window and Ukraine, and then mixed with inactive ingredients and put into syringes in pharmacies.

Even so, Sherkow said, "if Novo sues them, if they have a U.S. patent that covers it all, then making, using, selling, offering to sell or importing semaglutide for sale into the U.S. could be an infringement." However, litigation would take time and money, he said, and would also be complicated by patents that may involve "pharmaceutical preparations" - essentially finished products - rather than the active ingredients themselves.