Januvia, Byetta double pancreatitis risk, JAMA analysis finds

The diabetes treatments Januvia and Byetta may double patients' risk of pancreatitis, a new study finds. The drugs, sold by Merck ($MRK) and a Bristol-Myers Squibb ($BMY)/AstraZeneca ($AZN) partnership, have been linked to pancreatitis before, but the JAMA Internal Medicine study puts a number to that risk for the first time.

Researchers analyzed insurance records to find that patients hospitalized with pancreatitis were twice as likely to be using Januvia or Byetta, when compared with diabetics who didn't have pancreatitis, Bloomberg reports. "This is the first real study to give an estimate of what the risk is," said study author Sonal Singh, assistant professor at Johns Hopkins University. "[U]ntil now we just had a few case reports."

It was on the basis of those case reports that the FDA issued safety alerts for both drugs. In 2007, the agency flagged pancreatitis cases in Byetta patients, and did the same for Januvia in 2009. In 2008, the FDA amped up label warnings on Byetta after 6 deaths in patients who had developed pancreatitis, though four of them couldn't be causally linked to the condition. Besides the risks of acute pancreatitis itself, the condition boosts the risk of pancreatic cancer.

Both companies defended their drugs' safety. Merck told Bloomberg that it has reviewed the data and found "no compelling evidence of a causal relationship" between Januvia and pancreatitis or pancreatic cancer. Bristol-Myers said it and AstraZeneca are confident in the "positive benefit-risk profile" of Byetta and its long-lasting formulation Bydureon, and promised to "continue to carefully monitor" post-marketing reports.

Merck's Januvia franchise is a whopper. The drug itself brought in $4 billion for Merck last year. Its sister combo treatment, Janumet, which combines Januvia with the common diabetes drug metformin, added another $1.65 billion. Merck recently gave up developing a combination of Januvia and the now-off-patent Lipitor.

Byetta is less lucrative for Bristol-Myers and AstraZeneca, with $148 million in 2012 sales (and another $159 million for Eli Lilly ($LLY) under its marketing partnership). But one reason Bristol-Myers bought Amylin Pharmaceuticals was Byetta. The drugmaker figured it and AZ could apply their Big Pharma marketing power to pump up the drug's sales.

- read the Bloomberg story