- Patients receiving a stable antiparkinsonian treatment that may involve, in addition to L-DOPA, a dopamine agonist, a monoamine oxidase-B (MAO-B) or a catecholamine O-methyl transferase (COMT) inhibitor, an anti-cholinergic for at least 2 months before enrollment and in whom we presume it will be possible to maintain this treatment unchanged during the study period (except the dose of L-dopa which can be adjusted during the study after the third month of Phase 1).