Exelon, a drug for Alzheimer’s disease developed by Swiss drugmaker Novartis, appears to be as effective as a treatment for dementia in Parkinson’s disease patients, according to US Food and Drug Administration officials.

But the reviewers stopped short of drawing any conclusions on whether Exelon (rivastigmine) should be approved in the latter indication, deferring to the FDA’s Peripheral and Central Nervous System Drugs advisory committee, which meets to deliberate on the application later today.

The review document asks the panel to consider if there is a distinct form of dementia associated with Parkinson’s and, if so, whether it can be reliably diagnosed. This would be required if the FDA was to allow a new claim.

Exelon was approved by the FDA in April 2000 to treat mild-to-moderate dementia caused by Alzheimer’s. At the moment there is no drug approved to treat dementia associated with Parkinson’s, according to the review, so a recommendation for approval could add some momentum to Exelon sales, which came in at $467 million last year but slipped 1% to $116 million in the first quarter of 2006, with US sales down 13% to $42 million.

On the other hand, analysts said it would not be a major problem for Novartis if Exelon did not get the go-ahead for the new indication, as the drug’s importance to the Swiss drugmaker is receding.

Exelon was cleared to treat Parkinson's disease in Switzerland in January, and has also been recommended for approval in this indication by the European Commission. It is also registered for Parkinson's in several Latin American countries, including Brazil.