Doctors are reducing Avandia prescriptions.

From July through September of 2007, nearly 70 percent of the prescription changes for Avandia were the result of withdrawals, or physicians switching patients to another therapy, according a new research from TNS Healthcare published in the quarterly DiabetesDynamics.

The research showed that the rate of withdrawals is also accelerating, with as many withdrawals in third quarter of 2007 alone as in the first and second quarters combined.

Philip O’Hagan, international client services director for TNS Healthcare, said that “From January through June, 84 percent of prescribing changes were positive—physicians starting new patients on Avandia, adding it to existing regimens or switching patients to Avandia from other therapies. From July forward, however, we see a dramatic turnaround, with the majority of Avandia changes now coming from doctors taking patients off the drug.”

The research also revealed that one of the main reasons physicians are switching patients from Avandia is reports that the drug is linked with increased cardiovascular risks.

“Clearly, reports of Avandia being linked to increased cardiovascular risk are having a huge impact on prescribing decisions,” said O’Hagan. “The market upheaval is likely to continue and grow, as negative news hits about other diabetes drugs—such as the recent withdrawal of Exubera and concerns over Byetta’s potential link to acute pancreatitis.”

TNS provides market research consulting to the pharmaceutical, biotech and medical device industries.