Prescriptions for Avandia take a plunge

Health scare hits diabetes pill

Physicians shied away from prescribing GlaxoSmithKline's Avandia during the first two days after a study linking the anti-diabetes pill to an increased risk of heart attack was published last week.

Data from ImpactRx, a New Jersey company that tracks prescriptions written by physicians, suggests that on May 22 and 23, Avandia's market share dropped from about 10 percent of prescriptions written for diabetes pills to nearly zero. The share of prescriptions written for Actos, a competing medicine made by Takeda Pharmaceutical, more than doubled to 22 percent.

The reaction was far worse than some analysts had expected. But Patrick Angelastro, ImpactRx's senior vice president of strategic development, cautioned that two days' worth of data isn't enough to say Avandia has fallen out of favor with physicians.

"You don't know whether it's a knee-jerk reaction or whether it'll last," Angelastro said. "The data gets more robust as time goes by."

Avandia is the No. 2 seller for GSK, the British company with a U.S. headquarters in Research Triangle Park. About 1 million Americans take the pill, which generated about $3 billion in sales last year. Some analysts had expected sales to increase to $4 billion this year.

Since the New England Journal published the study May 21 that suggested Avandia raises cardiovascular risks by 43 percent, GSK's American depository receipts, which are similar to stock, have dropped nearly 10 percent. The ADRs closed at $52.06 Tuesday, down 37 cents.

Deutsche Bank analysts wrote in a report to investors Tuesday that the stock could continue to fall if lost Avandia sales hurt GSK's earnings.

But GSK spokeswoman Mary Anne Rhyne cautioned about misinterpreting the ImpactRx data.

"We understand this is based on two days of prescription data from a very small sampling of physicians, which is not enough to reach sensible conclusions on the trend for Avandia new prescriptions," Rhyne wrote in an e-mail message.

ImpactRx monitors the number of prescriptions that physicians write daily, but did not release more up-to-date data on Avandia.