Botox-type drugs are attracting adverse notice from the US Food and Drugs Administration.
A little after it approved Dysport, a rival to Botox, the agency said both drugs, along with a third called Myobloc, should carry black-box warnings to alert patients and doctors to serious safety risks.
sections of the labeling for both Botox and Myobloc products note that important systemic adverse effects, including severe difficulty swallowing and difficulty breathing have occurred in patients with neuromuscular disorders after local injection of typical doses of botulinum toxin.
FDA now has evidence that similar, potentially life-threatening systemic toxicity from the use of botulinum toxin products can also result after local injection in patients with other underlying conditions such as those with cerebral palsy associated limb spasticity. Systemic toxicity has been reported in children, several of whom required feeding tubes and/or ventilation (breathing) support.
Use of botulinum toxins for treatment of limb spasticity (severe arm and leg muscle spasms) in children or adults is not an approved use in the U.S.
In an "Early Communication about an Ongoing Safety Review Botox and Botox Cosmetic (Botulinum toxin Type A) and Myobloc (Botulinum toxin Type B)," the agency said, "The reactions reported are suggestive of botulism, which occurs when botulinum toxin spreads in the body beyond the site where it was injected."
Botox (botulinum toxin type A) is approved for treatment of conditions such as blepharospasm (spasm of the eyelids), cervical dystonia (severe neck muscle spasms), and severe primary axillary hyperhydrosis (excess sweating). Botox Cosmetic, also botulinum toxin Type A, is approved for temporary improvement in the appearance of moderate to severe facial frown lines.
Myobloc (botulinum toxin Type B) is approved for the treatment of adults with cervical dystonia; the safety and effectiveness of Myobloc for cervical dystonia in children have not been established.
FDA is aware of the body of literature describing the use of botulinum toxins to treat limb spasticity in children and adults. The safety, efficacy and dosage of botulinum toxins have not been established for the treatment of limb spasticity of cerebral palsy or for use in any condition in children less than 12 years of age.
Until such time that FDA has completed its review, healthcare professionals who use medicinal botulinum toxins should:
Be alert to the potential for systemic effects following administration of botulinum toxins such as: dysphagia, dysphonia, weakness, dyspnea or respiratory distress
Understand that these effects have been reported as early as one day and as late as several weeks after treatment
Provide patients and caregivers with the information they need to be able to identify the signs and symptoms of systemic effects after receiving an injection of a botulinum toxin
Tell patients they should receive immediate medical attention if they have worsening or unexpected difficulty swallowing or talking, trouble breathing, or muscle weakness
The agency took care to add, "This early communication is in keeping with FDA's commitment to inform the public about its ongoing safety reviews of drugs. FDA will communicate to the public its conclusions, resulting recommendations, and any regulatory actions after the review of the data are completed. "This information reflects FDA's current analysis of available data concerning these drugs. Posting this information does not mean that FDA has concluded there is a causal relationship between the drug products and the emerging safety issue. Nor does it mean that FDA is advising healthcare professionals to discontinue prescribing these products. FDA is considering, but has not reached a conclusion about whether this information warrants any regulatory action. FDA intends to update this document when additional information or analyses become available "