WASHINGTON (Reuters) - U.S. regulators said on Friday they were reviewing the safety of Allergan Inc's Botox and a competing product after reports of deaths and serious reactions in some patients.
The U.S. Food and Drug Administration said the most serious cases included hospitalizations and deaths and occurred mostly in children treated for cerebral palsy-associated limb spasticity, a use not approved in the United States.
The FDA said its review applied to Allergan's Botox and Botox Cosmetic, and Solstice Neurosciences Inc's Myobloc.
The reactions reported are suggestive of botulism, which occurs when the botulinum toxin used in the products spreads in the body beyond the injection site, the FDA said.
Reactions were reported in cases involving approved and unapproved uses and a variety of doses, the FDA added.
"FDA is currently reviewing safety data from clinical studies submitted by the manufacturers of Botox, Botox Cosmetic and Myobloc, as well as post-marketing adverse event reports and the medical literature," the agency said in a notice posted on its Web site.
Until the FDA completes its review, doctors and patients should watch for signs of botulinum effects in the body such as weakness, trouble swallowing or respiratory distress.
An Allergan spokeswoman had no immediate comment. Officials at Solstice Neurosciences could not be immediately reached.
Allergan shares were down $3.99, or almost 4 percent, after the FDA announcement, to $63.32 on the New York Stock Exchange in midday trade.
Jefferies & Co analyst Peter Bye said a likely outcome would be for the FDA to require a black box warning highlighting the adverse events with Botox and discouraging prescribing it for unapproved uses.
But, Bye said, a similar warning took place in Europe, and "We didn't see any hiccups in European growth when the warnings were put on."
Bye said the stock decline was likely unwarranted, noting Botox's strong safety track record.
"There obviously is some risk" of more severe FDA action, Bye said. "But given the history of the product ... I wouldn't think it's high."
Greater FDA scrutiny could work in Allergan's favor, Bye said. It could mean there will be a longer U.S. review period for Reloxin, a potential Botox rival from Medicis Pharmaceutical Corp.
