IncobotulinumtoxinA Shows Long-Term Treatment Effect on Parkinson Disease Sialorrhea
Swallowing difficulties, a major concern for patients with Parkinson disease, occurred rarely in the study, and were spontaneously resolved over time.
Bruno Bergmans, MD
Interim findings from a longitudinal study assessing incobotulinumtoxinA injection in patients with advanced Parkinson disease (PD) further confirmed its therapeutic benefit and safety as a treatment option for sialorrhea, or excessive drooling. Patients showed significant benefits for up to 6 months after initially starting treatment, with several of those continuing to receive the planned 3-monthly injection intervals over a 4-year period.1
Using a cohort of 32 patients with advanced PD (average age, 79 [±6] years), findings showed that patients treated with 100 units of incobotulinumtoxinA experienced decreases in total Drooling Severity and Frequency Scale (DSFS) 6 weeks after the second injection, from 7.5 (±1.1) at baseline to 6.0 (±1.3). These data were presented at the 2023 International Congress of Parkinson’s Disease and Movement Disorders (MDS), held August 27-31, in Copenhagen, Denmark, by lead investigator Bruno Bergmans, MD, Department of Neurology, AZ Sint-Jan.
In the study, patients with PD suffering from sialorrhea were injected with a total of 100 units of incobotulinumtoxinA in a 3:2 ratio parotid vs submandibular gland bilaterally based on anatomical landmarks every 3 months, unless prolonged effect allowed for a longer interinjection interval up to 6 months. Efficacy, determined using the 7-point Likert Global Impression of Change Scale (GICS), was consistently improved, with patients demonstrating mean scores of 2.9 (±1.2) at 6 weeks after injection 1 and 2.8 (±1.1) at 6 weeks after injection 2.
In total, 3 patients showed efficacy up to 6 months and 2 patients stopped injections after 2 and 7 cycles, respectively, because of sustained benefit and minimal residual sialorrhea. All other patients continued with their 3-monthly intervals of treatment. Adverse events (AEs) were recorded in 10.3% (16 of 154) of overall cycles, with dry mouth, swallowing difficulties, and taste disturbances as the only treatment-related AEs. Swallowing difficulties occurred in 5 cycles (3.2%) among 4 patients and were spontaneously resolved. Two patients also had their dosage reduced to 75 units because of moderate swallowing difficulties.
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In general, oral medication therapies for sialorrhea have been the mainstay treatment for sialorrhea, but use of these medications is often limited by significant and heterogenous AEs, black box warning in the elderly, and suboptimal benefit. Typical oral therapy includes anticholinergic drugs such as hyoscine, scopolamine, glycopyrrolate, and ipratropium. These drugs operate by blocking cholinergic receptors, and thus decreasing the production of saliva by inhibiting cholinergic parasympathetic and postganglionic sympathetic activity.
In 2020, incobotulinumtoxinA became the first and only FDA-approved neuromodulator for the treatment of patients aged 2 years and older with chronic sialorrhea. The basis of the approval came from a phase 3, prospective, randomized, double-blind, placebo-controlled study of 255 children and adolescents aged 2 to 17 years. Results showed that the treatment significantly reduced unstimulated Salivary Flow Rate, or the primary end point, compared with placebo at 4 among patients aged 6 to 17 weeks, and sustained efficacy over 64 weeks.2
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