IncobotulinumtoxinA (Xeomin, Merz Pharmaceutials) injected into the salivary glands provides lasting improvement in chronic sialorrhea (excessive drooling), new research shows.

Results of the Sialorrhea in Adults Xeomin Investigation (SIAXI) study, the phase 3 trial that led to US approval, were published online March 27 in Neurology.

The findings provide “Class I evidence that incobotulinumtoxinA reduces salivary flow rates in patients with chronic sialorrhea,” note the researchers, led by Wolfgang Jost, MD, PhD, from Parkinson-Klinik Ortenau, Wolfach, Germany.

Sialorrhea is a common symptom among patients who suffer from neurologic disorders such as Parkinson disease (PD), amyotrophic lateral sclerosis, or cerebral palsy or who have experienced a stroke or traumatic brain injury (TBI).

Sialorrhea has adverse effects on the quality of life of patients and caregivers. Effects range from difficulty eating and speaking, with social and emotional consequences, to an increased risk for morbidity and mortality associated with aspiration pneumonia and the breakdown of perioral skin.

The SIAXI study enrolled 184 adults with PD (70.7%), atypical parkinsonism (8.7%), stroke (19.0%), or TBI (2.7%). Patients were randomly allocated to double-blind treatment with placebo (36 patients) or incobotulinumtoxinA 75 U (74 patients) or 100 U (74 patients) injected bilaterally into the parotid and submandibular salivary glands.

At week 4, both incobotulinumtoxinA dose groups showed reductions in mean unstimulated salivary flow rate (a primary endpoint). In the higher-dose group, there was a significant difference compared to placebo (P = .004).

Patients’ Global Impression of Change Scale scores (coprimary endpoint) also improved at week 4, again with a significant difference vs placebo in the incobotulinumtoxinA 100 U group (P = .002).

A lasting effect greater than placebo was also observed at week 16, “suggesting a duration of efficacy of incobotulinumtoxinA of at least 16 weeks and benefit to the patient that may extend beyond 4 months after the initial injection,” the researchers say.

Both doses of incobotulinumtoxinA were well tolerated. The incidence of treatment-related adverse events was similar for the treatment and placebo groups. The most frequent adverse events were dry mouth and dysphagia.

These data from the SIAXI trial led the US Food and Drug Administration to approve incobotulinumtoxinA 100 U for the treatment of chronic sialorrhea in adults in July 2018.

The study was funded by Merz Pharmaceuticals. Jost and several coauthors have disclosed financial relationships with the company.

Neurology. Published online March 27, 2019. Abstract

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