Seville orange juice is an inhibitor of the intestinal cytochrome P450 (CYP) 3A4 enzyme, one of the enzymes responsible for the metabolism of colchicine. This study will evaluate the effect of multiple daily consumptions of Seville orange juice on the pharmacokinetic profile of a single 0.6 mg dose of colchicine. A secondary objective is to evaluate the safety and tolerability of this regimen in healthy volunteers. All study subjects will be monitored for adverse events throughout the study period.

Seville orange juice is an inhibitor of the intestinal cytochrome P450 (CYP) 3A4 enzyme, one of the enzymes responsible for the metabolism of colchicine. This study will evaluate the effect of multiple daily consumptions of Seville orange juice on the pharmacokinetic profile of a single 0.6 mg dose of colchicine. Twenty-four healthy, non-smoking, non-obese, non-pregnant adult volunteers between the ages of 18 and 45 will be given one dose of colchicine (1 x 0.6 mg tablet) on Day 1, after an overnight fast. Fasting will continue for 4 hours after the dose. Blood samples will be drawn from all participants before dosing and for 24 hours post-dose to adequately define the baseline pharmacokinetics of colchicine. After a 14 day washout period, starting on the morning of Day 15 and continuing through Day 17, subjects will return to the clinic for consumption of an administered 240 ml dose of Seville orange juice in the morning and evening. At 8am on Day 18 after an overnight fast, all subjects will receive a co-administered single oral dose of colchicine (1 x 0.6 mg) and Seville orange juice (1 x 240 ml). Fasting will continue for 4 hours after the dose. Blood samples will be drawn from all participants before dosing and for 24 hours post-dose to adequately define the pharmacokinetics of colchicine in the presence of Seville orange juice. Subjects will consume the final administered 240 ml dose of Seville orange juice in the evening on Day 18. A further goal of this study is to evaluate the safety and tolerability of this regimen in healthy volunteers. Subjects will be monitored throughout participation in the study for adverse reactions to the study drug and/or procedures. Seated blood pressure and pulse will be measured prior to dosing and at approximately 1, 2, and 3 hours following drug administration on Days 1 and 18 to coincide with peak plasma concentrations of colchicine. All adverse events whether elicited by query, spontaneously reported, or observed by clinic staff will be evaluated by the investigator and reported in the subject's case report form.

Inclusion Criteria:

• Healthy adults 18-45 years of age
• Non-smoking and non-pregnant (post-menopausal, surgically sterile or using effective contraceptive measures)
• Body mass index (BMI) greater than or equal to 18 and less than or equal to 32, inclusive
• Hemoglobin greater than or equal to 11.5g/dL

Exclusion Criteria:

• Recent participation (within 28 days) in other research studies
• Recent significant blood donation or plasma donation
• Pregnant or lactating
• Test positive at screening for human immunodeficiency virus (HIV), hepatitis B surface antigen (HbsAg), or hepatitis C virus (HCV)
• Recent (2-year) history or evidence of alcoholism or drug abuse
• History or presence of significant cardiovascular, pulmonary, hepatic, gallbladder or biliary tract, renal, hematologic, gastrointestinal, endocrine, immunologic, dermatologic, neurologic, or psychiatric disease
• Subjects who have used any drugs or substances known to inhibit or induce cytochrome (CYP) P450 enzymes and/or P-glycoprotein (P-gp) within 28 days prior to the first dose and throughout the study
• Drug allergies to colchicine
• Intolerance or food allergy to Seville orange juice

24 subjects were enrolled in this study. One subject was withdrawn from the study due to failure to arrive for the Day 15 Seville orange juice dose.