The study will be conducted in two parts. The first is a parallel-group design, evaluating doses of 40 mg, 80 mg or 120 mg BCX-4208. The second part is planned as a dose-escalation study, evaluating higher doses including 160 mg, 240 mg and 320 mg BCX-4208. The study's primary endpoint is the change in uric acid in the blood compared to baseline measurement prior to treatment, assessed on Day 22.