An Extension Study to Assess the Safety, Tolerability and Efficacy of ABT-SLV187 in Subjects With Advanced Parkinson's Disease and Persistent Motor-Complications Despite Optimized Treatment With Available Anti-Parkinsonian Medications

Inclusion Criteria: 1. Subjects completing 12 weeks treatment in Study M12-921 who would benefit from long-term treatment from ABT-SLV187. Alternatively, subjects who (i) participated in the Phase 2 Study M12-925 (ii) would, in the opinion of the Investigator, benefit from ABT-SLV187 treatment in the Study M12-923, (iii) did not discontinue the M12-925 Study due to safety reason, and (iv) meet all entry requirements. Lastly, subjects who completed another ABT-SLV187 study (e.g., Study M12-927) in South Korea. 2. The subject must be able to understand the nature of the study and must provide written informed consent prior to the conduct of any study procedures (including any changes occurring in the subject's current therapeutic regimen). 3. The subject must be willing to continue on treatment. Exclusion Criteria: 1. Subject is enrolled in another clinical trial. 2. Psychiatric, neurological or behavioral disorders that may interfere with the ability of subjects to give informed consent, or interfere with the conduct of the study. 3. Medical, laboratory, or surgical issues deemed by the Investigator to be clinically significant and in the opinion of the PI, would be a contraindication to continued levodopa therapy. 4. Uncooperative attitude or reasonable likelihood for non-compliance with the protocol. 5. Subject has current significant suicidal ideation as evidenced by answering "yes" to questions 4 or 5 on the suicidal ideation portion of the Columbia-Suicide Severity Rating Scale completed at the Week 12 Visit of Study M12-921 or at the Baseline Visit of the current study for M12-925 or M12-927 study subjects. 6. Consideration by the Investigator, for any reason, that the subject is an unsuitable candidate to continue to receive ABT-SLV187.