FDA orders 'black box' for Botox, Dysport

It hasn't been a good week for Botox. The Allergan blockbuster got its first U.S. competitor yesterday, when FDA approved Ipsen's similar wrinkle-fighter and muscle relaxant Dysport. Now, the agency follows up with a black-box warning of possibly serious side effects--a warning long sought by consumer advocate Public Citizen.

At least the warning doesn't apply only to Botox. Dysport will have to carry the infamous black box, too. In this case, the heavy-duty warning will have to explain that the paralytic botulinum toxin can migrate from the site where it's injected, even to parts of the body far distant. The agency has received hundreds of adverse event reports to that effect, with some patients developing serious problems, such as difficulty swallowing or breathing.

In addition to revising the label's warning language, the drugmakers also will have to send "dear doctor" letters that enumerate the possible risks. And they'll have to produce a medication guide for patients.

Most of the severe side effects happened in patients who'd been treated with the toxin off-label. These patients got high doses--even overdoses--for unapproved uses such as limb spasticity in children with cerebral palsy, FDA officials said. Administered at approved doses and for approved uses, the drugs are safe, the agency said.

Meanwhile, some analysts are estimating that Allergan could lose a third of its Botox market to Dysport, which will be sold in the U.S. by Medicis. Why? Because the drug could be priced as much as 15 percent lower than Botox, which would allow it to chip away at the older drug's hold on the market. Of course, Allergan is ramping up a big PR effort to combat an erosion in sales. Prepare for an intense fight [1], folks.

- see the release [2] from FDA
- read the New York Times story [3]
- check out the BNet Pharma post [4]
- here's Public Citizen's statement on the warning [5]

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