This is an open label study evaluating the long term safety and tolerability of PF-06649751 in Parkinson's disease patients who experience motor-fluctuations. Subjects who completed Ph2 study B7601003 will be randomized to one of 4 treatment groups (15 mg QD, 7 mg QD, 3 mg QD, or 1 mg QD group) depending on the treatment received in B7601003 and titrated up to 15 mg QD over a 3 week period, as appropriate. All subjects who were blindly down-titrated during the B7601003 study will remain at/or be titrated to 7 mg QD only and remain at that dose for the rest of the B7601017 study in order to protect the blind for the prior study. Subjects who successfully titrate to 15 mg QD will enter the Adjustment Period at that dose.