Prestudy screening will be conducted within 4 weeks of the first study phase. Subjects will undergo a complete medical history, social history (including medication, alcohol, and tobacco use), physical examination, standard 12-lead electrocardiogram (ECG), and laboratory screening to assure that inclusion and exclusion criteria are met. The laboratory screening data to be obtained are: complete blood count, prothrombin time (PT), international normalized ratio (INR), macroscopic and microscopic urinalysis, electrolytes, blood urea nitrogen (BUN), serum creatinine, aspartate transaminase (AST), alanine transaminase (ALT), total bilirubin, and serum albumin. Women of childbearing potential (defined as premenopausal with no history of hysterectomy or tubal ligation) will undergo a serum pregnancy test during the screening visit and a urine pregnancy test prior to each phase of the study. Following enrollment, subjects will participate in each of the 4 study phases in a random order.