The U.S. Food and Drug Administration (FDA) recently approved
onabotulinumtoxin A (Botox) as a treatment to decrease spasticity in various
muscle groups of the upper limb.
In three clinical trials reviewing the effect of the drug on wrist and
finger flexors, as well as on elbow flexors and the biceps, Botox effectively
reduced muscle tone. Spasticity in the upper extremities is common after
stroke, traumatic brain injury and the progression of multiple sclerosis.
Russell Katz, MD, director of the division of neurology products in the
FDA’s Center for Drug Evaluation and Research, told O&P Business
News that the FDA’s decision was relatively straightforward.
“It quite clearly showed an effect on spasticity, on decreasing
muscle tone in those muscle groups,” he said. “They examined a
relatively wide range of doses, and we thought it clearly demonstrated that the
drug was effective in reducing muscle tone.”
These findings were consistent with using Botox as a treatment for other
This treatment would benefit patients cosmetically, as well as
hygienically; patients whose hands permanently rest in the flexor position have
difficulty cleaning and maintaining their skin.
“We now have evidence from well-designed and well-conducted
clinical trials that Botox works to decrease spasticity in various muscle
groups of the upper limb,” Katz said. “We can now write labeling to
tell them how to do that so that it will be effective and it will be
Researchers did not determine if there was increased function in the
affected limb, nor did they look at whether there was an improvement in
disability — the study examined only the effects of this treatment on
spasticity that is the result of these disabilities.
He also emphasized the need for education regarding the spread of the
effects of Botox — reduced muscle tone, causing difficulties swallowing
and breathing — to other areas of the body, namely the respiratory
muscles. These effects, which are noted in a boxed warning for the drug, can
take several weeks after the injections to manifest.
Both physicians and patients must be aware of these potential side
effects. Although they are rare, he said, patients need to recognize any side
effects and inform their practitioner as soon as possible.
FDA regulations require that this product also be studied in the
pediatric population. Additionally, Katz said the agency has requested that
sponsors perform these studies in the lower limb as well, since Botox is used
off-label in treating lower limb spasticity. Without the proper knowledge of
its effects, more patients — particularly pediatric patients — are at
risk of the effects of the spread of toxins. — by Stephanie Z. Pavlou