FDA reviews reports linking botulinum toxins to systemic adverse reactions

The U.S. Food and Drug Administration has reviewed post-marketing reports linking botulinum toxins types A and B to systemic adverse reactions after use of FDA-approved and unapproved treatments, the agency said in a press release.

Botox (botulinum toxin type A, Allergan) is approved for treating blepharospasm, cervical dystonia and severe primary axillary hyperhidrosis. Botox Cosmetic is approved for cosmetic treatment of moderate-to-severe facial frown lines. Myobloc (botulinum toxin type B, Solstice Neurosciences) is approved for treating adults with cervical dystonia. It has not been approved for treating children with cervical dystonia, according to the release.

The reports indicate a marked incidence of botulism, which occurs when botulinum toxin proliferates in the body outside the injection site, the release said.

The most serious adverse reactions occurred in children treated for limb spasticity associated with cerebral palsy — a treatment that is not currently approved by the FDA in the United States — and, in some cases, resulted in hospitalization and death.

Complications have been reported as early as 1 day and as late as several weeks after treatment, according to the release.

"The 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 release said.

The FDA has advised health care professionals to be aware of differing potency determinations among botulinum toxin products and to understand the potential for and severity of systemic adverse reactions.

In separate press releases, Allergan and Solstice Neurosciences expressed support for the FDA review.

Botox is also indicated for ophthalmic use for treating strabismus and dystonia-associated blepharospasm in patients 12 years or older.