Since the 1980s, the MAO-B inhibitors have gained considerable status in the therapy of the Parkinson's disease. In addition to the symptomatic effect in mono- and combination therapies, a neuroprotective effect has repeatedly been a matter of some discussion, which has unfortunately led to a good many misunderstandings. Due to potential interactions, selegiline has declined in significance in the field. For the MAO-B inhibitor safinamide, recently introduced to the market, an additional inhibition of pathological release of glutamate has been postulated. At present, rasagiline and selegiline are being administered in early therapy as well as in combination with levodopa. Safinamide has been approved only for combination therapy with levodopa when motor fluctuations have occurred. MAO-B inhibitors are a significant therapeutic option for Parkinson's disease, an option which is too often not appreciated properly. 

/pdf/a-critical-appraisal-of-mao-b-inhibitors-in-the-treatment-of-15iebndv.pdf

A critical appraisal of MAO-B inhibitors in the treatment of Parkinson’s disease

Abstract Non-motor symptoms (NMS) are common among patients with Parkinson’s disease and reduce patients’ quality of life (QOL). However, there remain considerable unmet needs for NMS management. Three monoamine oxidase B inhibitors (MAO-BIs), selegiline, rasagiline, and safinamide, have become commercially available in many countries. Although an increasing number of studies have reported potential beneficial effects of MAO-BIs on QOL and NMS, there has been no consensus. Thus, the primary objective of this study was to provide an up-to-date systematic review of the QOL and NMS outcomes from the available clinical studies of MAO-BIs. We conducted a literature search using the PubMed, Scopus, and Cochrane Library databases in November 2021. We identified 60 publications relevant to this topic. Overall, rasagiline and safinamide had more published evidence on QOL and NMS changes compared with selegiline. This was likely impacted by selegiline being introduced many years prior to the field embarking on the study of NMS. The impact of MAO-BIs on QOL was inconsistent across studies, and this was unlikely to be clinically meaningful. MAO-BIs may potentially improve depression, sleep disturbances, and pain. In contrast, cognitive and olfactory dysfunctions are likely unresponsive to MAO-BIs. Given the paucity of evidence and controlled, long-term studies, the effects of MAO-BIs on fatigue, autonomic dysfunctions, apathy, and ICD remain unclear. The effects of MAO-BIs on static and fluctuating NMS have never been investigated systematically. More high-quality studies will be needed and should enable clinicians to provide personalized medicine based on a non-motor symptom profile. 

https://www.nature.com/articles/s41531-022-00339-2.pdf

Effects of MAO-B inhibitors on non-motor symptoms and quality of life in Parkinson’s disease: A systematic review

Levodopa remains the gold standard for the treatment of Parkinson’s disease, but its long-term use is associated with motor complications whose management is still a significant challenge. Safinamide is a multimodal drug with proven efficacy as an adjunct to levodopa. The objective of this study was to investigate the efficacy and safety of safinamide as an add-on to levodopa in Chinese patients with Parkinson’s disease with motor fluctuations. The XINDI study was a phase III, randomized, double-blind, placebo-controlled, multicenter study, with a 2-week screening period and a 16-week treatment period. The starting dose of safinamide (or placebo) was 50 mg once daily, increased to 100 mg once daily at day 15. Patients aged ≥ 18 years, with idiopathic Parkinson’s disease of >3 years duration, Hoehn and Yahr stage 1–4, and daily OFF time ≥ 1.5 h, were eligible. Patients should follow a stable oral levodopa regimen and may receive concomitant treatment with stable doses of other anti-Parkinson drugs, except monoamine oxidase-B inhibitors. Patients with severe disabling peak-dose or biphasic dyskinesia, unpredictable or widely swinging fluctuations, other forms of parkinsonism, a history of dementia or severe cognitive dysfunction, major psychiatric illnesses, and/or clinically significant medical illnesses were excluded. The primary efficacy endpoint was the change from baseline to week 16 in the mean daily OFF time. Secondary efficacy endpoints included the Unified Parkinson’s Disease Rating Scale, the Numerical Rating Scale, the Clinical Global Impression scale, and the 39-Item Parkinson’s Disease Questionnaire scale. The statistical analysis of the efficacy parameters was conducted using an analysis of co-variance, except for the Clinical Global Impression scale scores that were assessed using the Wilcoxon–Mann–Whitney test. Safety was evaluated through the frequency of adverse events and serious adverse events, physical examination, vital signs, 12-lead electrocardiograms, and laboratory exams. All safety endpoints were summarized using descriptive statistics. The trial enrolled 307 patients. At week 16, the difference in the change of the mean total daily OFF time between safinamide and placebo groups was 1.10 h (p < 0.0001). This change was significantly greater in the safinamide group starting from week 2, suggesting a rapid onset of drug efficacy. ON time, Unified Parkinson’s Disease Rating Scale, Clinical Global Impression scale, and the 39-Item Parkinson’s Disease Questionnaire showed statistically significant improvements. There were no significant between-group differences for adverse events or serious adverse events. Safinamide, as add-on therapy to levodopa, significantly reduced motor fluctuations and improved motor symptoms and quality of life of Chinese patients with idiopathic Parkinson’s disease. The improvements observed in the Unified Parkinson’s Disease Rating Scale total and motor scores were also clinically significant. No safety concerns were identified, confirming the good tolerability profile of the drug. NCT03881371, registered on 19 March, 2019, https://clinicaltrials.gov/NCT03881371 . 

/pdf/the-xindi-study-a-randomized-phase-iii-clinical-trial-6xnibc1j.pdf

The XINDI Study: A Randomized Phase III Clinical Trial Evaluating the Efficacy and Safety of Safinamide as Add-On Therapy to Levodopa in Chinese Patients with Parkinson’s Disease with Motor Fluctuations

http://www.jns-journal.com/article/S0022510X21027854/pdf

Characteristics of wearing-off and motor symptoms improved by safinamide adjunct therapy in patients with Parkinson's disease: A post hoc analysis of a Japanese phase 2/3 study

/pdf/effects-of-mao-b-inhibitors-on-non-motor-symptoms-and-3mn7nhpr.pdf

Javier Pagonabarraga

Papers

The role of glutamatergic neurotransmission in the motor and non-motor symptoms in Parkinson's disease: Clinical cases and a review of the literature.