Dr Stuart IsaacsonStuart Isaacson, MD
The FDA has approved a supplemental biologics license application for rimabotulinumtoxinB (Myobloc, US WorldMeds) injection for the treatment of chronic sialorrhea in adults. This adds to its existing approval for the treatment of cervical dystonia, which it was granted in 2000.1

The US WorldMeds agent is the first and only approved botulinumtoxin type B. In clinical trials, it showed significant decreases in sialorrhea symptoms with a single treatment as soon as the first week, lasting up to 3 months.2

"Sialorrhea can be highly distressing for patients and their caregivers and can have a significant, negative impact on the quality of life,” Stuart Isaacson, MD, director, Parkinson's Disease and Movement Disorder Center of Boca Raton, said in a statement. “If left untreated, pooling of saliva can lead to irritation of the skin around the mouth, oral hygiene complications, speech difficulties, and sleep interruption. In some cases, pooling of saliva can lead to choking and aspiration pneumonia.”

The presence of sialorrhea is common in a number of neurologic disorders, including amyotrophic lateral sclerosis (ALS), Parkinson disease, stroke, and cerebral palsy, among others. Literature suggests that up to three-quarters of those with Parkinson are impacted by excessive drooling, with many citing it as one of the most bothersome symptoms.3

“In addition to the physical consequences, the social stigma associated with drooling can be severe enough to result in social withdrawal,” Isaacson said. “These impacts can leave patients with compromised physical wellbeing, as well as feeling embarrassed by their condition, causing a lack of confidence and isolation."

In a clinical trial of rimabotulinumtoxinB in 54 patients with Parkinson,  in which subjects received a single intraglandular treatment with botulinum toxin type B (doses of 1,500 Units [0.3 mL]; 2,500 Units [0.5 ml]; or 3,500 Units [0.7 ml]) or placebo. At 4 weeks, Drooling Frequency and Severity Scale scores were 1.3 (±1.3) better than placebo, in a dose-related manner, respectively (-2.1 [±1.2], P =.0191; -3.3 [±1.4], P <.0001; -3.5 [±1.1], P <.0001). As well, unstimulated salivary flow rates significantly decreased in all active groups versus placebo (P ≤.0009).

The authors of the study concluded that “treated subjects appeared to have a more sustained improvement in sialorrhea than placebo subjects.” Additionally, an open-label portion of the trial suggested that subsequent dosing sessions over the course of 1 year were just as safe and effective.

The most common adverse events (AEs) in clinical studies were dry mouth, dental caries, and dysphagia.

"We are committed to helping patients who struggle with confidence due to their sialorrhea. This new indication for MYOBLOC offers a fast-acting and proven treatment," said P. Breckinridge Jones, CEO, US WorldMeds, in a statement. "We are proud to support health care providers with an option that can have such a positive impact on the lives of patients and their caregivers."

According to US WorlMeds, Myobloc is currently available in 3 vial sizes and is the only botulinum toxin therapy available that requires no reconstitution.
REFERENCES
1. FDA Approves US WorldMeds' MYOBLOC® (rimabotulinumtoxinB) Injection for Chronic Sialorrhea [press release]. Louisville, KY: US WorldMeds; Published August 26, 2019. biospace.com/article/releases/fda-approves-us-worldmeds-myobloc-rimabotulinumtoxinb-injection-for-chronic-sialorrhea. Accessed August 27, 2019.
2. Chinnapongse R, Gullo K, Nemeth P, Zhang Y, Griggs L. Safety and efficacy of botulinum toxin type B for treatment of sialorrhea in Parkinson's disease: a prospective double-blind trial. Mov Disord. 2012;27(2):219-226. doi: 10.1002/mds.23929.
Martinez-Martin P, Rodriguez-Blazquez C,  Kurtis MM, et al. The impact of non-motor symptoms on health-related quality of life of patients with Parkinson's disease. Movement Disord.2011;26(3):399–406. doi: 10.1002/mds.23462.