FDA approves Botox for the treatment of lower limb spasticity in adults

Botox is the first and only FDA-approved neurotoxin treatment for both upper and lower limb spasticity.

Botox was first approved for the treatment of upper limb spasticity (ULS), or increased muscle stiffness in the elbow, wrist and fingers, in adults in March 2010. Additional FDA approval was received in April 2015 to expand the Botox label for the treatment of adults with ULS to include the addition of two thumb muscles. It is not known whether Botox is safe or effective to treat increased stiffness in upper limb muscles other than those in the elbow, wrist, fingers, and thumb, or to treat increased stiffness in lower limb muscles other than those in the ankle and toes. Botox has not been shown to help people perform task-specific functions with their upper limbs or increase movement in joints that are permanently fixed in position by stiff muscles. Treatment with Botox is not meant to replace your existing physical therapy or other rehabilitation that your doctor may have prescribed.

"Spasticity is a debilitating condition that can have a significant impact on patients' lives, compromising their ability to perform a range of daily activities," said Mitchell F. Brin, Senior Vice President Global Development and Scientific Officer, Botox. "This FDA approval marks our continued commitment to partnering with scientists and researchers around the world to explore the potential benefits of Botox in treating specific medical conditions. We are pleased that through this research, we are now able to offer this treatment option for patients with lower limb spasticity."

Spasticity is a condition in which there is an abnormal increase in muscle tone or stiffness of muscle, which may interfere with movement, or be associated with discomfort. Affecting approximately 1 million people in the US, spasticity is usually caused by damage to the portion of the brain or spinal cord that controls voluntary movement. The most common causes of spasticity include stroke, adult cerebral palsy, multiple sclerosis, traumatic brain injury, spinal cord injury, physical trauma, or infection.

"In my experience, stroke survivors are among the most prominent groups to be impacted by spasticity affecting the upper and lower limbs; and it is critical to continue seeking treatment from a physician specially trained to manage spasticity," said Alberto Esquenazi, John Otto Haas Chair and Professor, Department of Physical Medicine and Rehabilitation; Director, Gait & Motion Analysis Laboratory, MossRehab, and a lead investigator in the studies. "The results reinforce the efficacy and safety of Botox, and physicians can now have even greater confidence when offering their patients another approach to treating these specific muscles."

The FDA approval was based on a large, international development program that included a phase three, multi-center, double-blind, randomized, placebo-controlled clinical trial that evaluated the safety and efficacy of Botox compared to placebo in more than 400 patients with lower limb spasticity following stroke. The study compared a total Botox dose of 300 to 400 units divided among ankle and toe muscles (n=233) to placebo (n=235). Statistically significant improvements were observed in the two co-primary endpoints of average change from baseline in the improvement of muscle tone measured by the Modified Ashworth Scale (MAS) ankle score and the clinical benefit for patients as assessed by the Clinical Global Impression of Change by Physician (CGI) at weeks 4 and 6 (p<0.05). The most frequently reported adverse reactions (>2%) were arthralgia (3%), back pain (3%), myalgia (2%), upper respiratory tract infection (2%) and injection site pain (2%). The safety profile observed in the study was consistent with the known safety profile of Botox.