A One-Directional, Open-Label Drug Interaction Study to Investigate the Effects of Multiple-Dose Ketoconazole on Single-Dose Pharmacokinetics of Colchicine in Healthy Volunteers

Ketoconazole is a potent inhibitor of the cytochrome P450 (CYP) 3A4 enzyme system, one of the enzyme systems responsible for the metabolism of colchicine. This study will evaluate the effect of multiple doses of ketoconazole 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. After a fast of at least 10 hours, twenty-four healthy, non-smoking, non-obese, non-pregnant adult volunteers between the ages of 18 and 45 years will be given one dose of colchicine (1 x 0.6 mg tablet) orally on Day 1. Fasting will continue for 4 hours after the dose. Blood samples will be drawn from all participants before dosing and for twenty-four hours post-dose on a confined basis at times sufficient to adequately define the pharmacokinetics of colchicine. Blood sampling will then continue on a non-confined basis on Days 2-5. On Days 15-18, subjects will return to the clinic daily for non-confined dosing of ketoconazole (1 x 200 mg tablet) twice daily, every 12 hours. Administered ketoconazole doses on these days will not necessarily be in a fasted state. On Day 15, after taking the first dose of ketoconazole, subjects will remain in the clinic for observation for 1 hour post-dose administration. Then, on Day 19, co-administration of a single dose of colchicine (1 x 0.6 mg tablet) and ketoconazole (1 x 200 mg tablet) will occur following a fast of at least 10 hours in subjects confined to the clinic for dosing and 24-hour blood sampling will be performed at times sufficient to adequately determine the pharmacokinetics of colchicine. Blood sampling will continue on a non-confined basis on Days 20-23. Fasting will continue for 4 hours following the co-administered dose of ketoconazole and colchicine. The final dose of ketoconazole (1 x 200 mg tablet) will be administered to subjects the evening of Day 19, in a non-fasting state. 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. Vital signs (blood pressure and pulse) will be measured prior to dosing and at 1, 2, and 3 hours following drug administration on Days 1 and 19 to coincide with peak plasma concentrations of both colchicine and ketoconazole. 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.