The safety news over Avandia has made its mark on physicians' prescribing decisions, and the therapy is now prescribed less often for new patients than any other branded diabetes treatment.
While Byetta and Avandia tangoed in the bottom position of the diabetes market over the past few months, ImpactRx data shows that Avandia clearly lost its footing to become docs' least-favorite brand to prescribe at the start of Q4 2007.
It's not that the Amylin/Lilly drug Byetta is free of safety concerns. The treatment has been linked with an increase of acute pancreatitis. Still, it doesn't seem that physicians and patients are reacting. "It's not new news," said Richard Altus, CEO of ImpactRx. "Rather, it's the formalization of something we already know."
The type II diabetes market generated $11.2 billion in 2006. Around one-third of new patients are prescribed generic metformin. But since Avandia's fallout in May, the market has evolved into a two-horse race between Merck's Januvia and Takeda's Actos in terms of share of new starts and promotional intensity, said Altus. While Avandia maintained about 15 percent of new patient starts before May 2007, when Dr. Steven Nissen published a meta-analysis in the New England Journal of Medicine linking Avandia to increased cardiovascular risk, is now hovers right below 5 percent.
Avandia prescribing has always been dynamic, according to Philip O'Hagan, international client services director for TNS Healthcare, with physicians frequently changing patients' course regimens and adding on therapies. During the first half of 2007, 20 percent of patient visits resulted in some kind of therapy change. But most of the time, those changes were positive for Avandia. From July through September, reports O'Hagan, nearly 70 percent of changes in Avandia prescribing were the result of patient switches to other therapies.