TRENTON, N.J. (AP) -- Shares of several pharmaceutical companies that make widely used, newer diabetes medicines fell Thursday, after U.S. regulators warned they are looking into potential risks of drugs in two classes of diabetes treatments.
The Food and Drug Administration said it is seeking more information about evidence found by academic researchers that the two groups of drugs can raise the risk of inflammation of the pancreas and cellular changes in the insulin-making organ that occur before cancer. However, the agency recommended patients keep taking their medicine until they discuss it with their doctor.
Merck & Co., based in Whitehouse Station, N.J., and Denmark's Novo Nordisk A/S were hardest hit, as their drugs in question account for 12 percent of each company's annual revenue.
Merck makes Januvia and three drugs that combine its active ingredient with another medicine: Janumet, extended-release Janumet and Juvisync. Those drugs brought in a total of about $5.75 billion last year. That makes them the company's biggest franchise since allergy and asthma drug Singulair, which had been bringing in about $5.5 billion a year, had its U.S. patent expire in August.
In early afternoon trading, Merck shares were down 48 cents, or 1.1 percent, at $48.11, after initially falling 2.2 percent.
Novo Nordisk's U.S. shares were down $1.43, of 0.8 percent, at $173.22. They had fallen 1.4 percent before recovering somewhat.
Novo makes the once-a-day injection Victoza, which brought in about $1.7 billion last year. That's far less than the Merck drugs, but Novo Nordisk is known as the world's biggest seller of insulin and about 80 percent of its total revenue comes from products to treat diabetes.
Bristol-Myers Squibb Co., which has been expanding its diabetes business with partner AstraZeneca PLC of Great Britain, now sells four diabetes drugs: injections Byetta and Bydureon and the pills Onglyza and Kombiglyze.
Shares of New York-based Bristol-Myers were down 30 cents, or 0.8 percent, at $38.19. However, U.S. shares of AstraZeneca rose 46 cents, or 1 percent, to $46.31.
Shares of Eli Lilly and Co. of Indianapolis, which sells the pills Tradjenta and Jentadueto, were down 9 cents at $54.97.
The remaining three drugs now under scrutiny are lesser-known pills sold by Japan's Takeda Pharmaceuticals: Nesina, Kazano and Oseni. Takeda's U.S. shares were up 61 cents, or 2.3 percent, at $26.84.
The injected drugs are all in the class called GLP-1 and are taken by nearly 1 million Americans, according to health data firm Kantar Health. These drugs work by mimicking the effects of a natural hormone that causes the body to make more insulin, the hormone that reduces levels of sugar in the blood by making it enter cells that turn the sugar, or glucose, into energy.
The pills under scrutiny are in the class called DPP-4 inhibitors, taken by about 1.6 million Americans, according to Kantar. These drugs work by stimulating insulin release and, at the same time, inhibiting release of a hormone that raises blood sugar levels.
The FDA previously added information about some fatal cases of pancreatitis to the detailed package inserts for Byetta, in 2007, Januvia and Janumet, in 2009.
Linda A. Johnson can be followed at https://twitter.com/LindaJ_onPharma