Colchicine is a supressor of hepatic CYP1A2 and theophylline is a sensitive CYP1A2 probe substrate. When the two are co-administered the potential exists for a clinically significant drug interaction. This study aims to determine the effect of steady-state colchicine on the pharmacokinetics of theophylline administered as a single dose. After a fast of at least 10 hours, thirty healthy, non-smoking, non-obese, non-pregnant adult volunteers between the ages of 18 and 45 will be given one dose of 300mg (80mg/15ml concentrate) theophylline (theophylline elixir) on Day 1. 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 on a confined basis at times sufficient to adequately determine the pharmacokinetics of theophylline. Blood sampling will then continue on a non-confined basis on days 2-3. A four day washout period will be completed after the theophylline dose on Day 1 and prior to administration of the first colchicine dose on Day 5. Participants will return to the clinic on days 5-18 for non-confined dosing of colchicine (1x0.6mg twice daily every 12 hours). Administered dosing on these days will not necessarily be in a fasted state. Co-administration of a single 300mg dose of theophylline (80mg/15ml) and colchicine (1x0.6mg) will occur on the morning of Day 19 following a fast of at least 10 hours. Twelve hours later, subjects will receive the last dose of colchicine (1x0.6mg). Blood samples will be drawn from all participants before dosing on Day 19 and for 24 hours post-dose on a confined basis at times sufficient to adequately determine the pharmacokinetics of theophylline. Blood sampling will then continue on a non-confined basis on days 20 and 21. 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, 5 (after the morning dose) and 19. 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.
Colchicine is a supressor of hepatic CYP1A2 and theophylline is a sensitive CYP1A2 probe substrate. When the two are co-administered the potential exists for a clinically significant drug interaction. This study aims to determine the effect of steady-state colchicine on the pharmacokinetics of theophylline administered as a single dose. A secondary goal is to evaluate the safety and tolerability of this regimen in healthy volunteers. All study subjects will be monitored for adverse events throughout the entire study period.