This is an open label non-randomized single sequence, single group two way drug interaction study in healthy adult volunteers to determine the extent to which quinine, an inducer of cytochrome p450 CYP 3A4, affects the pharmacokinetics of midazolam, an accepted probe drug for CYP 3A4. The study will also determine the extent to which midazolam affects the pharmacokinetics of quinine.

This is an open label single sequence single group non-randomized two way drug interaction study in healthy adult volunteers to determine the extent to which quinine, an inducer of cytochrome p450 CYP 3A4, affects the pharmacokinetics of midazolam, an accepted probe drug for CYP 3A4. The study will also determine the extent to which midazolam affects the pharmacokinetics of quinine. This will compare the pharmacokinetics of midazolam and quinine at baseline to their kinetics when they are taken together in 24 normal healthy adult volunteers who will serve as their own controls. All patients will be confined to the study site throughout the entire 11 day study period. On day 1 after a fast of at least 10 hours, all study participants will receive a single oral dose of midazolam 2 mg. Blood will be drawn at times sufficient to adequately define the baseline concentration time curve for midazolam and its metabolite, 1-hydroxy-midazolam. On the morning of day 4, after a 3 day washout period and following a fast of at least 10 hours, all volunteers will begin a regimen of 324 mg of quinine sulfate by mouth every 8 hours. All subjects will continue this regimen from day 4-10 (21 total doses). Blood will be drawn after the first daily dose of quinine on days 4 and 9 at times sufficient to adequately define the baseline and steady state concentration time curves for quinine. Additional blood will be drawn prior to the first daily dose of quinine on days 7,8,9,and 10. On day 10 after a fast of at least a 10 hours, all participants will receive both midazolam 2 mg and quinine 324 mg together. Blood will be drawn a times sufficient to characterize the pharmacokinetics of midazolam, 1-hydroxy-midazolam and quinine under the stated conditions.

Inclusion Criteria:

• Medically healthy non-smoking, non-obese (≥ 60 kg males, ≥52 kg females within 15% of IBW) adult volunteers 18-45 years of age

Exclusion Criteria:

• Subjects with history or presence of significant cardiovascular disease (including hypotension, hypertension, bradycardia or EKG abnormalities), pulmonary, hepatic, gallbladder or biliary tract, renal, hematologic, gastrointestinal, endocrine, immunologic, dermatologic, neurologic, psychiatric disease or an active sexually transmitted disease.
• Subjects with significant blood loss in the prior 56 days, plasma donation within 7 days , hemoglobin < 12.0 g/dl or who have participated in another clinical trial within the prior 30 days.
• Subjects with recent (2-year) history or evidence of alcoholism or drug abuse.
• Subjects who have used any drugs or substances known to inhibit or induce cytochrome P450 (CYP) enzymes 10 days or 28 days respectively prior to the first dose and throughout the study.
• Subjects who have received monoamine oxidase inhibitors or been on a special diet within 28 days of starting the study.
• Subjects who test positive at screening for human immunodeficiency virus (HIV), hepatitis B surface antigen (HbsAg), or hepatitis C virus (HCV).

Subjects who are pregnant or lactating, taking hormone replacement therapy or have known allergies to quinine sulfate, mefloquine, quinidine or midazolam and other benzodiazepines.