The US Food and Drug Administration (FDA) has approved onabotulinumtoxinA (Botox, Allergan Inc) to decrease the severity of stiffness in ankle and toe muscles among adults with lower limb spasticity, the company has announced.
The approval was based on a large, development program that included a phase 3, multicenter, double-blind, randomized clinical trial that evaluated the safety and efficacy of placebo and Botox at a dose of 300 to 400 units divided among ankle and toe muscles in more than 400 patients with lower limb spasticity following a stroke.
The study showed statistically significant improvements at weeks 4 and 6 in the average change in muscle tone, measured by the Modified Ashworth Scale ankle score, and in clinical patient benefit, as assessed by the Clinical Global Impression of Change by Physician. Benefits were observed for arthralgia, back pain, myalgia, upper respiratory tract infection, and injection site pain.
The safety profile was consistent with the known safety profile of the product in other indications.
Patients with spasticity have an abnormal increase in muscle tone or stiffness, which may interfere with movement or cause discomfort. Spasticity affects about 1 million people in the United States. The most common causes are adult cerebral palsy, multiple sclerosis, traumatic brain injury, spinal cord injury, physical trauma, or infection, in addition to stroke.
"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," commented Alberto Esquenazi, MD, chair and professor, Department of Physical Medicine and Rehabilitation, MossRehab, Elkins Park, Pennsylvania, and a lead investigator in the studies, in the press release.
The product was first approved for the treatment of upper limb spasticity, consisting of 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 label for the treatment of adults with upper limb spasticity to include the addition of two thumb muscles.
It is not known whether it 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, the release notes.
"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, MD, senior vice president global development and scientific officer, Botox, in a company press release.
"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."
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Cite this: FDA Approves Botox for Lower Limb Spasticity - Medscape - Jan 26, 2016.