A Study to Compare IPX066 and Carbidopa/Levodopa/Entacapone (CLE) Followed by an Open-Label Safety Study of IPX066

This is a randomized, double-blind, double-dummy, 2 treatment, 2-period crossover study followed by an open-label extension study period.

Inclusion criteria

• Diagnosed with idiopathic Parkinson's Disease (PD).
• At least 30 years old at the time of PD diagnosis.
• Currently being treated with carbidopa/levodopa/entacapone (CLE) and on a stable regimen of conventional LD for at least 4 weeks and:

• Requiring a total daily levodopa (LD) dose of at least 400 mg
• Having a minimum dosing frequency of four times per day.
• Individual CD-LD or CLE doses that contain an LD dose which is a multiple of 50 mg.
• Able to differentiate "on" state from "off" state.
• Have predictable "off" periods.
• Amantadine, anticholinergics, selective monoamine oxidase (MAO) type B inhibitors (e.g., selegiline, rasagiline) or dopamine agonists are allowed as long as the doses and regimens have been stable for at least 4 weeks prior to Screening and the therapy is intended to be constant throughout the course of the study.
• Agrees to use a medically acceptable method of contraception throughout the study and for 1 month afterward.

Exclusion criteria

• Diagnosed with atypical Parkinsonism or any known secondary Parkinsonian syndrome.
• Nonresponsive to LD therapy.
• Prior functional neurosurgical treatment for PD (e.g., ablation or deep brain stimulation) or if such procedures are anticipated during study participation.
• Received within 4 weeks of Screening or planning to take during participation in the clinical study: any controlled-release LD product, tolcapone, apomorphine, nonselective MAO inhibitors, or antipsychotics including neuroleptic agents for the purpose of treating psychosis or bipolar disorder.
• Allergy or hypersensitivity to CD, LD, entacapone, riboflavin, Yellow Dye #5 (tartrazine), citrus fruit or grape juice.
• History of or currently active psychosis.
• Active or prior medical conditions such as peptic ulcers or prior surgical (e.g., bowel) procedures that would interfere with LD absorption.
• Active or history of narrow-angle glaucoma.
• History of malignant melanoma or a suspicious undiagnosed skin lesion.
• History of myocardial infarction with residual atrial, nodal, or ventricular arrhythmias, upper gastrointestinal hemorrhage, or neuroleptic malignant syndrome or nontraumatic rhabdomyolysis.
• Received any investigational medications during the 4 weeks prior to Screening.
• Unable to swallow large pills (e.g., large vitamin pills).
• Pregnant or breastfeeding.
• Subjects who are unable to complete a symptom diary.