Botox, Myobloc to Undergo FDA Safety ReviewFeb 8, 2008 | Parker Waichman LLP
Botox, Botox Cosmetic and Myobloc, medications made with botulism toxin, are now being reviewed by the Food & Drug Administration (FDA). The FDA said it has received reports of systemic adverse reactions including respiratory compromise and death following the use of Botox, Botox Cosmetics and Myobloc.
Botox, which is made with 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, which also uses botulinum toxin Type A, is approved for temporary improvement in the appearance of moderate to severe facial frown lines. Myobloc, which is made from botulinum toxin Type B, is approved for the treatment of adults with cervical dystonia.
According to the FDA, the Botox, Botox Cosmetic and Myobloc reactions reported are suggestive of botulism, which occurs when botulinum toxin spreads in the body beyond the site where it was injected. The most serious cases had outcomes that included hospitalization and death, and occurred mostly in children treated for cerebral palsy-associated limb spasticity. 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.
According to the FDA, pediatric botulism cases occurred in patients less than 16 years old, with reported symptoms ranging from dysphagia to respiratory insufficiency requiring gastric feeding tubes and ventilatory support. Serious outcomes included hospitalization and death. The most commonly reported use of botulinum toxin among these cases was treatment of limb muscle spasticity associated with cerebral palsy. For Botox, doses ranged from 6.25 to 32 Units/kilogram (U/kg) in these cases. For Myobloc, reported doses were from 388 to 625 U/kg.
The reports of adult botulism cases described symptoms including patients experiencing difficulty holding up their heads, dysphagia and ptosis. Some reports described systemic effects that occurred distant from the site of injection and included weakness and numbness of the lower extremities. Among the adult cases that were serious, including hospitalization, none required intubation or ventilatory support. No deaths were reported. The doses for Botox ranged from 100 to 700 Units and for Myobloc from 10,000 to 20,000 U.
The FDA has advised that healthcare professionals who use medicinal botulinum toxins should understand that potency determinations expressed in “Units” or “U” are different among the botulinum toxin products; clinical doses expressed in units are not comparable from one botulinum product to the next. Physicians should also be alert to the potential for systemic effects following administration of botulinum toxins such as: dysphagia, dysphonia, weakness, dyspnea or respiratory distress and Understand that these effects have been reported as early as one day and as late as several weeks after treatment. Patients and caregivers should be provided 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. Finally, healthcare providers should tell patients to receive immediate medical attention if they have worsening or unexpected difficulty swallowing or talking, trouble breathing, or muscle weakness.
The FDA said it is currently reviewing safety data from Botox, Botox Cosmetic and Myobloc clinical studies submitted by the drugs' manufacturers, as well as post-marketing adverse event reports and medical literature. After completing a review of the data, the FDA said it will communicate to the public its conclusions, resulting recommendations, and any regulatory actions.