Patients will be in the fasted state in the seated position throughout the study. They will be connected to an automated blood pressure monitor (Dinamap). Thirty minutes after baseline blood pressure and heart rate measurements, they will be given a dose of the medicine to be tested. Blood pressure will be monitored every 5 to 15 minutes for up to four additional hours. Upright blood pressure, heart rate and the standing time will be measure periodically throughout the study. The patients will be asked to rate their symptoms at various time during the study.