Merz Therapeutics Presents New Research at World Parkinson Congress 2026, Revealing the Hidden Burden of "OFF" Episodes in Parkinson’s Disease

A new qualitative literature review provides a comprehensive model of the patient experience of OFF episodes, identifying 132 distinct motor, non-motor and quality-of-life impacts1 The research highlights OFF episode as a complex, multifaceted experience, highlighting the profound and often invisible struggles faced by people with Parkinson’s disease1 Additional analyses of levodopa inhalation powder (INBRIJA®) confirm its clinical profile as a rapid, reliable and well-tolerated on-demand treatment for OFF episodes2,3

Merz Therapeutics, a leading player in neurology-focused specialty pharma, today announced the presentation of new research at the World Parkinson Congress (WPC) 2026 that uncovers the multifaceted burden of "OFF" episodes in Parkinson's disease (PD). The qualitative literature review demonstrates that these episodes are not only a re-emergence of motor symptoms, but also a complex mix of debilitating motor and non-motor symptoms that impact the lives of people with Parkinson’s disease.¹ Additional data presented at the congress also confirm the clinical profile of levodopa inhalation powder (INBRIJA^®) as a reliable and well-tolerated treatment for these debilitating events.

The new research moves beyond well-recognized physical signs to create a more comprehensive model for understanding the true patient experience of an OFF episode.¹ The systematic review identified 132 distinct concepts, detailing the profound impact of "invisible" non-motor symptoms such as fatigue, memory problems and anxiety, which can be just as, if not more, debilitating.¹ This work provides a new framework for clinicians and the wider community to appreciate the complex, multi-faceted burden of OFF episodes and underscores the critical need for effective on-demand solutions.¹

"For too long, the conversation around 'OFF' episodes has focused primarily on visible motor symptoms. Our research highlights what we’ve been hearing from people with Parkinson’s: the burden of an 'OFF' episode is far broader and more disruptive than what can be seen," said Dr. Stefan Albrecht, CSO, Merz Therapeutics. "It is a call to action for the entire Parkinson's community to recognize and address the significant impact of ‘OFF’ episodes. At Merz Therapeutics, we’re committed to delivering effective and reliable therapeutic options to help address the needs of people with Parkinson’s disease."

Supporting its commitment to delivering on-demand treatments, Merz Therapeutics also presented key data on the efficacy and safety of a levodopa inhalation powder (INBRIJA^®):

• A pooled analysis of 437 people with Parkinson’s disease from three Phase III trials demonstrated that levodopa inhalation powder (INBRIJA^®) provides consistent and rapid motor improvement for people who had been experiencing OFF episodes for a shorter time (<2 years) as well as a longer time (≥2 years) before initiation of therapy, with mean UPDRS-III score reductions of -14.3 and -14.8, respectively.²
• A dedicated safety analysis confirmed a favorable tolerability profile, showing that treatment-emergent adverse events, primarily cough and throat irritation, were mostly mild with no dose-dependent increase in severity. Furthermore, after 60 weeks of treatment, the probability of a patient remaining free of treatment-related cough was 84.7%.³

The research was presented at the WPC in Phoenix, Arizona, from May 24–27, 2026.

About OFF Episodes in Parkinson's Disease

"OFF episodes" are the re-emergence of Parkinson's disease symptoms, both motor (such as tremor and slowness) and non-motor (like anxiety and fatigue), that occur despite a patient's regular medication schedule. These episodes can be unpredictable and severely disrupt a person's ability to perform daily activities, creating significant challenges for people with Parkinson’s disease, their families and caregivers.

About Merz Therapeutics

Merz Therapeutics GmbH is dedicated to delivering better outcomes for more patients. With science as its foundation and the patient experience as its focus, the company relentlessly pursues innovative treatments and partnerships to address unmet needs in movement disorders, neurodegenerative conditions, liver disease, and other health conditions that severely impact patients’ quality of life.

Merz Therapeutics is headquartered in Frankfurt am Main, Germany, and is active in more than 80 countries. Merz Therapeutics GmbH is part of the Merz Group, a privately held, family-owned company with a more than 115-year legacy. With passion and purpose, Merz Therapeutics continues to advance care in specialty neurology in ways that benefit both patients and society.

Please visit www.merztherapeutics.com.

References

1. Scheschonka A et al., Episodes of motor and non-motor response fluctuations (OFF episodes) in people with Parkinson disease: a targeted qualitative literature review and preliminary patient-centric conceptual model. Presented at: World Parkinson Congress (WPC); May 24-27, 2026; Phoenix, AZ.
2. Scheschonka A et al., Efficacy and safety of inhaled levodopa comparing early and late treatment initiation in patients with Parkinson disease: post hoc analysis of pooled data from three phase III trials. Presented at: World Parkinson Congress (WPC); May 24-27, 2026; Phoenix, AZ.
3. Scheschonka A et al., Safety of inhaled levodopa by incidence and severity of treatment-related cough and throat irritation in people with Parkinson disease: post hoc analysis of pooled data from three phase III trials. Presented at: World Parkinson Congress (WPC); May 24-27, 2026; Phoenix, AZ.

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