The current study will explore the efficacy, safety and tolerability of 2 dose combinations of JM-010 to determine the optimal doses of each component to be studied in confirmatory clinical trials.

This is a Phase 2, double-blind, double-dummy, placebo-controlled, randomized, parallel group, multicentre study.

Subjects with a diagnosis of moderate to severe dyskinesia in Parkinson's disease (PD) will complete a Screening Visit to assess eligibility to participate in the study.

Subjects will continue with their usual levodopa treatment regimen for the duration of study participation.

The screening assessment period will be a minimum of 1 week up to a maximum of 6 weeks. Subjects deemed to be eligible at the end of the Screening Visit will be randomly assigned in a 1:1:1 ratio to receive either 1 of the 2 dose combinations of JM-010 and 1 placebo, or 2 placebos as per the double-dummy study design. The randomized subjects will be followed treatment periods for 12 weeks and safety follow periods for 2 weeks, including pharmacokinetic (PK) sub-study.

Inclusion Criteria:

• Is able to read, understand, and provide written, dated informed consent prior to Screening Visit.
• Is male or female, between 18 and 80 years of age at Screening Visit.
• Is diagnosed with idiopathic PD that meets UK Parkinson's Disease Society (UKPDS) Brain Bank Clinical Diagnostic Criteria and requires treatment with and shows responsiveness to levodopa.
• Has experienced dyskinesia over a period of at least 3 months prior to Screening Visit
• Has stable peak-effect dyskinesia
• Has more than one hour of "ON" time with troublesome dyskinesia during daily waking hours on a 24-hour PD subject diary
• Is on a stable levodopa dosing regimen requiring at least 3 dose administrations but no more than 6 dose administrations per day

Exclusion Criteria:

• Has undergone surgery for the treatment of PD
• Has a current diagnosis of Substance Use (including alcohol) Disorder (Abuse or Dependence, as defined by Diagnostic and Statistical Manual, Fifth Edition [DSM 5]),
• Has psychiatric diagnosis of acute psychotic disorder or other psychiatric diagnoses
• Has a significant risk for suicidal behaviour in the opinion of the investigator during the course of their participation in the study
• Has current seizure disorders (other than febrile seizures in childhood) requiring treatment with anticonvulsants.
• Has known serious ongoing symptomatic cerebral disease or cerebrovascular disease or any acute brain trauma requiring treatment with anti-convulsant therapy within 5 years prior Visit 2, Week 0 (Baseline Visit).
• Has a history of exclusively diphasic, OFF state, myoclonic, dystonic, or akathetic dyskinesia without peak-dose dyskinesia.

Other criteria related to other medical conditions to be referred to the protocol.

Double-blind, double-dummy.