May cause drowsiness or sleepiness. Concurrent use of other CNS depressants may cause additive sedative effects. Orthostatic and/or sustained hypotension reported. Hallucinations reported. May cause and/or exacerbate pre-existing states of confusion or hallucinations. Pulmonary fibrosis, pleuritis, pleural effusion, pleural fibrosis, pericarditis, pericardial effusion, cardiac valvulopathy (involving 1 or more valves), or retroperitoneal fibrosis reported rarely. A symptom complex resembling neuroleptic malignant syndrome (e.g. elevated temperature, muscular rigidity, altered consciousness, autonomic instability) reported in association with rapid dosage reduction of, withdrawal of, or changes in antiparkinsonian therapy. May potentiate adverse dopaminergic effects of levodopa and may cause or exacerbate pre-existing dyskinesias. Arrhythmias (e.g. atrial premature contractions, sinus tachycardia) reported. Use with caution in patients prone to cardiac dysrhythmias. Cardiac valvulopathy and other cardiac adverse effects reported. Increased incidence of confusion, somnolence, and peripheral edema reported in patients ≥65 years of age. Substantially eliminated by kidneys; risk of toxic reactions may be greater in impaired renal function.