Black Box Warning Required for All Botulinum Toxin Products by FDA
The FDA has announced changes to the safety label on botulinum toxin due to reports that the effects of the toxin may spread from the area of injection to other areas of the body causing serious adverse problems. This new label requirement is required on Botox and Botox Cosmetic (botulinum toxin type A); Myobloc (botulinum toxin type B); and a new FDA-approved product, Dysport (abobotulinumtoxinA).
When the botulinum toxin spreads beyond the area injected the toxin can cause symptoms similar to those of botulism. These symptoms include unexpected loss of strength or muscle weakness, hoarseness or trouble talking, trouble saying words clearly, loss of bladder control, trouble breathing, trouble swallowing, double vision, blurred vision and drooping eyelids.
Even though these adverse events have been reported in adults most have been reported in children with cerebral palsy. These adverse events have been reported in patients treated for approved and unapproved (off-label) uses.
All three products (Botox, Myobloc, and Dysport) are approved by the FDA for the treatment of cervical dystonia (a condition marked by repetitive contraction of the neck muscles). Botox Cosmetic and Dysport are approved for use in the temporary improvement in the appearance of glabellar frown lines. Botox is approved for the treatment of severe underarm sweating (primary axillary hyperhidrosis), crossed eyes (strabismus), and abnormal tics and twitches of the eyelids (blepharospasm). All other uses are considered off-label.
Risk Evaluation and Mitigation Strategy (REMS) will now be necessary for all botulinum toxin products. Currently, Dysport is the only one with an available REMS as it was part of their product approval. The companies that manufacture Botox and Myobloc have 30 days to submit the requested label changes. The FDA is also requiring the manufacturers to collect safety data in children and adults with muscle spasticity to assess the signal of risk regarding distant spread of toxin effects.