 1. History of cardiovascular disease syncope, arrhythmia, or myocardial infarction within the last two years, systolic blood pressure greater than 150 or less than 70 mm Hg, diastolic blood pressure greater than 110 or less than 50 mm Hg, or heart rate greater than 110 or less than 50 beatsminute; impaired hepatic function total hepatic enzyme or bilirubin levels greater than 2 times the upper limits of normal or impaired renal function creatinine level greater than 2 times the upper limits of normal less than 6 months before the study 