The study will consist of two parts. Patients in Part A will receive a single dose of DPC 817 on two separate occasions and a placebo (a solution or tablet without the drug) on one occasion. Patients in Part B will receive two separate doses of DPC 817. Patients will be admitted to the clinical study unit the day before dosing (Day -1) and remain there for at least 48 hours after taking the study drug. Patients will return to the clinical study unit on Day 8 and Day 28 following the dose in the last treatment period. During the study there will be medical and medication histories taken, physical examinations, vital sign measurements, and routine clinical laboratory tests.