The purpose of this study is to determine the pharmacokinetics (how a drug is absorbed, distributed, and eliminated by the body) of moxifloxacin alone versus moxifloxacin given with rifapentine. Researchers believe that understanding how these tuberculosis drugs interact when given together may help to determine the best drug treatment plan for use in future studies. Volunteers will take moxifloxacin daily by mouth for the first part of the study and then moxifloxacin in combination with rifapentine during the second part of the study. Sixteen healthy men and women will be recruited from Johns Hopkins University School of Medicine to volunteer for this study. They will be required to stay in the inpatient unit twice, each time for 84 hours. Study procedures will include having a tube placed in a vein to draw several blood samples over time. Volunteers will participate in the study for a maximum of 48 days, including screening and follow-up visits.
New drugs are urgently needed to shorten the duration of tuberculosis (TB) treatment and to facilitate the delivery of directly observed therapy. Preliminary data indicates that a TB treatment regimen that includes moxifloxacin plus rifapentine may have excellent antituberculosis activity that could allow for shortening of total TB treatment duration. However, little is known about possible pharmacokinetic interactions between the two drugs in humans. More specifically, moxifloxacin is metabolized via glucuronide and sulfate conjugation to inactive metabolites. Given that rifapentine induces the activity of phase II enzymes including glucuronosyltransferase and sulphotransferase, it is possible that rifapentine may alter the pharmacokinetics of moxifloxacin. This study will be a prospective, phase I, single center pharmacokinetic study in healthy subjects. The trial will compare the pharmacokinetics of moxifloxacin alone versus moxifloxacin administered with thrice-weekly rifapentine, each administered orally. There will be two parts to the trial: Part I (Days 1-4) during which moxifloxacin is administered alone; and Part II (Days 5-19) during which moxifloxacin is co-administered with thrice-weekly rifapentine. A 24-hour pharmacokinetic profile of moxifloxacin will be obtained following dose administration of moxifloxacin on Day 4 to obtain baseline steady state data at a dose of 400 mg daily. On Day 5, rifapentine will be added to the regimen at a dose of 900 mg thrice weekly, and a 48-hour pharmacokinetic profile for rifapentine and its metabolite, 25-desacetyl-rifapentine will be obtained after the first dose. On Day 19, 72-hour pharmacokinetic profiles for moxifloxacin, rifapentine, and 25-desacetyl-rifapentine will be performed. Safety and tolerability assessments will be performed at designated intervals throughout the study. Beginning on Day 1, subjects will receive moxifloxacin 400 mg daily for 19 days (Days 1-19). Beginning on Day 5, subjects will also receive rifapentine 900 mg thrice weekly (to be administered on Days 5, 7, 9, 12, 14, 16 and 19). Study participants will be 16 healthy adults, ages 18-65, recruited through Johns Hopkins University School of Medicine. The primary study objectives are to: compare, in healthy volunteers, the pharmacokinetics of moxifloxacin alone versus moxifloxacin co-administered with thrice-weekly rifapentine and describe the safety and tolerability of moxifloxacin co-administered with rifapentine. The secondary study objective is to evaluate for rifapentine autoinduction of metabolism in healthy volunteers receiving thrice-weekly rifapentine. The primary safety outcome will be the proportion of subjects with any Grade 3 or 4 toxicity associated with study medications or any serious adverse event. The secondary safety outcomes will be the proportion of subjects with any Grade 1 or 2 toxicity associated with study medications, and the proportion of subjects discontinuing study medications for any reason.