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Published Online: 15 December 2020

Safety and Tolerability of Cannabidiol in Parkinson Disease: An Open Label, Dose-Escalation Study

Publication: Cannabis and Cannabinoid Research
Volume 5, Issue Number 4


Background: Cannabis is increasingly used in Parkinson disease (PD), despite little information regarding benefits and risks.
Objectives: To investigate the safety and tolerability of a range of doses of cannabidiol (CBD), a nonintoxicating component of cannabis, and it's effect on common parkinsonian symptoms.
Methods: In this open-label study Coloradans with PD, substantial rest tremor, not using cannabis received plant-derived highly purified CBD (Epidiolex®; 100 mg/mL). CBD was titrated from 5 to 20–25 mg/kg/day and maintained for 10–15 days.
Results: Fifteen participants enrolled, two were screen failures. All 13 participants (10 male), mean (SD) age 68.15 (6.05), with 6.1 (4.0) years of PD, reported adverse events, including diarrhea (85%), somnolence (69%), fatigue (62%), weight gain (31%), dizziness (23%), abdominal pain (23%), and headache, weight loss, nausea, anorexia, and increased appetite (each 5%). Adverse events were mostly mild; none serious. Elevated liver enzymes, mostly a cholestatic pattern, occurred in five (38.5%) participants on 20–25 mg/kg/day, only one symptomatic. Three (23%) dropped out due to intolerance. Ten (eight male) that completed the study had improvement in total and motor Movement Disorder Society Unified Parkinson Disease Rating Scale scores of 7.70 (9.39, mean decrease 17.8%, p=0.012) and 6.10 (6.64, mean decrease 24.7%, p=0.004), respectively. Nighttime sleep and emotional/behavioral dyscontrol scores also improved significantly.
Conclusions: CBD, in the form of Epidiolex, may be efficacious in PD, but the relatively high dose used in this study was associated with liver enzyme elevations. Randomized controlled trials are needed to investigate various forms of cannabis in PD.

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Cite this article as: Leehey MA, Liu Y, Hart F, Epstein C, Cook M, Sillau S, Klawitter J, Newman H, Sempio C, Forman L, Seeberger L, Klepitskaya O, Baud Z, Bainbridge J (2020) Safety and tolerability of cannabidiol in Parkinson disease: an open label, dose-escalation study, Cannabis and Cannabinoid Research 5:4, 326–336, DOI: 10.1089/can.2019.0068.

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cover image Cannabis and Cannabinoid Research
Cannabis and Cannabinoid Research
Volume 5Issue Number 4December 2020
Pages: 326 - 336


Published online: 15 December 2020
Published in print: December 2020
Published ahead of print: 19 March 2020


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Maureen A. Leehey* [email protected]
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Ying Liu
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Felecia Hart
Department of Clinical Pharmacy, University of Colorado School of Medicine, Aurora, Colorado, USA.
Christen Epstein
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Mary Cook
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Stefan Sillau
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Jost Klawitter
Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Heike Newman
Regulatory Compliance Office, University of Colorado, Aurora, Colorado, USA.
Cristina Sempio
Department of Anesthesiology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Lisa Forman
Department of Gastroenterology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Lauren Seeberger
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Olga Klepitskaya
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Zachrey Baud
Department of Neurology, University of Colorado School of Medicine, Aurora, Colorado, USA.
Jacquelyn Bainbridge
Department of Clinical Pharmacy, University of Colorado School of Medicine, Aurora, Colorado, USA.


Address correspondence to: Maureen A. Leehey, MD, Department of Neurology, University of Colorado School of Medicine, 12631 E 17th Avenue, MS B185, Aurora, CO 80045, USA [email protected]

Author Disclosure Statement

No competing financial interests exist.

Funding Information

The study is funded by Colorado Department of Public Health and Environment. The study drug was provided by GW Research Ltd., Cambridge, United Kingdom. The study is supported by NIH/NCATS Colorado CTSA grant number UL1 TR001082-05. Contents are the authors' sole responsibility and do not necessarily represent official NIH views. Certain results from this study were generated using the “Questionnaire for Impulse Control Disorders in Parkinson's Disease (QUIP-RS),” licensed from the University of Pennsylvania.

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