Teva Pharmaceutical Industries' bid to get expanded approval for its Parkinson's disease drug Azilect has been dealt a crushing blow by advisors to the US Food and Drug Administration.

The agency's Peripheral and Central Nervous System Drugs Advisory Committee has unanimously voted that Azilect (rasagiline) has not been shown to slow progression of the disease. The drug is already approved to treat the symptoms of Parkinson's.

Currently no treatments are approved for slowing progression and given that the FDA panel voted 17-0 against recommending expanding approval for Azilect, it seems unlikely that the agency that will back the Teva drug.

The committee looked at data from a study of 1,176 patients with very early Parkinson's disease, who had not been treated previously. A 1mg dose of Azilect appeared to slow patients' disease, but the 2mg dose failed to show similar results. There were also disparate results between men and women and varying degrees of symptoms among patients studied.

The Globes newspaper quoted a statement from the FDA which notes that "the failure of the 2mg group raises serious questions about the interpretation of this study, and, therefore, about whether or not rasagiline has been shown to have disease-modifying effects. There is no obvious biological explanation for why the 2mg dose should not be disease-modifying, if the 1mg dose is".

However, the FDA acknowledged that there were no firm criteria for measuring a drug's ability to slow Parkinson's. Teva has yet to comment on the panel's vote.