Nebivolol in the Supine Hypertension of Autonomic Failure

Inclusion Criteria: * Male or female and aged 18 years or over. * Clinical diagnosis of orthostatic hypotension associated with Primary Autonomic Failure (Parkinson Disease, Multiple System Atrophy and Pure Autonomic Failure). * A documented fall in systolic blood pressure of at least 20 mmHg, or in diastolic blood pressure of at least 10 mmHg, within 3 minutes after standing. * Supine hypertension, defined as a systolic blood pressure \>150 mm Hg or diastolic blood pressure \> 90 mm Hg. * Provide written informed consent to participate in the study and understand that they may withdraw their consent at any time without prejudice to their future medical care. Exclusion Criteria: * Have changed dose, frequency and or type of prescribed medication, within two weeks of study start. * Women of childbearing potential who are not using a medically accepted contraception. * Have, in the investigator's opinion, any significant cardiac, systemic, hepatic, or renal illness. * Diabetes mellitus or insipidus. * In the investigator's opinion, have clinically significant abnormalities on clinical examination or laboratory testing. * In the investigator's opinion, are unable to adequately co-operate because of individual or family situation. * In the investigator's opinion, are suffering from a mental disorder that interferes with the diagnosis and/or with the conduct of the study, e.g. schizophrenia, major depression, dementia. * Are not able or willing to comply with the study requirements for the duration of the study. * Persons on drugs with beta-blocking potential (e.g., amiodarone), persons taking scheduled or as needed nitrates and persons on drugs with alpha-blocking potential (e.g. tamsulosin).