Objective: The clinical diagnosis of PD is based on demonstration of major motor manifestations on the neurologic exam, however, levodopa-responsiveness can be a very helpful supportive finding. Our objective was to demonstrate in a small pilot case series that novel in-clinic use of quick- acting inhaled levodopa (CVT-301) is feasible & effective in expediting the clinical diagnosis & subsequent management of PD.

Background: With PD being one of the fastest-growing neurodegenerative diseases, referrals to Neurology clinics to evaluate for PD is also growing dramatically. However, there are known limitations in accessing Neurologists which delays initiation of known beneficial symptomatic treatment. Even after an initial evaluation, it usually takes multiple appointments to obtain/review brain imaging & labs, exclude disease-mimics, & to implement/evaluate the effectiveness of a dopaminergic drug trial. Moreover, a significant proportion of tremor-predominant PD patients are still being misdiagnosed with essential tremor, delaying referral to research institutions for important disease-modifying trials.

Method: Ten patients were referred to a Neurology clinic located in Glenview, IL to evaluate symptoms concerning for PD. At the initial clinic visit, after informed consent, patients were provided a standard inhalation dose of CVT-301(84 mg levo-dopa) and videotaped pre- & post-PD-specific exams using the standard MDS-UPDRS Part III scale. Post-exams were scored 30 minutes following inhalation. An independent fellowship-trained Movement Disorders Neurologist confirmed levodopa-responsiveness based on review of the videotaped exams. At that same initial visit,L-dopa-responsive patients were prescribed oral Carbidopa/Levodopa & its effectiveness was evaluated at follow-up.

Results: 7/10 patients responded to the standard levodopa inhalation dose with improvement of MDS-UPDRS Part III Motor score ranging from 21.7% to 29.7% (mean 24.2%). The 3 patients who did not respond were subsequently diagnosed with drug-induced parkinsonism, PSP, & atypical axonal peripheral neuropathy with subcortical stroke.

Conclusion: Although inhaled levodopa CVT-301 was developed for “on-demand” treatment of sudden motor-OFF periods in PD,4 there is potential for the novel in-clinic use of this quick-

acting dopaminergic drug as a tool to expedite the diagnosis of PD without any clinically significant adverse events.

References: 1. Dorsey ER, Sherer T, Okun MS, Bloem BR. The Emerging Evidence of the Parkinson Pandemic. J Parkinsons Dis. 2018;8(s1):S3-S8.
2. Dall TM, Storm MV, Chakrabarti R, et al. Supply and demand analysis of the current and future US neurology workforce. Neurology. 2013;81(5):470-478.
3. Jain S, Lo SE, Louis ED. Common Misdiagnosis of a Common Neurological Disorder: How Are We Misdiagnosing Essential Tremor? Archives of Neurology. 2006;63(8):1100-1104.
4. Grosset DG, Dhall R, Gurevich T, et al. Inhaled levodopa in Parkinson’s disease patients with OFF periods: A randomized 12-month pulmonary safety study. Parkinsonism Relat Disord. 2020;71:4-10

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MDS Abstracts - https://www.mdsabstracts.org/abstract/novel-in-clinic-use-of-levodopa-inhalation-powder-cvt-301-as-an-outpatient-diagnostic-tool-for-parkinsons-disease/