Since many of the adverse events associated with quinine are dose-related, it is important to consider how varying degrees of renal dysfunction alter quinine pharmacokinetics possibly warranting dosage adjustment in these patients. This study will compare the pharmacokinetics of quinine in patients with normal, mild or moderate renal impairment. Eighteen non-smoking males and female volunteers between 18-65 years of age weighing at least 60 kg with BMI between 18- 40 kg/m2 will be divided into 3 groups of 6 subjects each based on renal function as defined (6 normal, 6 mild impairment, 6 moderate impairment). Subjects will be confined to the study unit during the entire 5 day study period beginning on the evening of Day -3. To confirm renal function classification, creatinine clearance will be measured via 24-hour urine collection from 7am Day -2 until 7am Day -1. On day 1, after a fast of at least 8 hours, each patient will receive a single 648 mg dose of quinine sulfate. Blood and urine samples will be collected at times sufficient to adequately define the pharmacokinetics of quinine and its active metabolite, 3'-hydroxyquinine) in the three study groups. Subjects will be monitored regarding adverse effects throughout study participation.