The Safety and Effectiveness of Rifabutin, Combined With Clarithromycin or Azithromycin, in HIV-Infected Patients

Overview

PER 03/10/94 AMENDMENT: PART B. To determine whether there is an effect on plasma drug levels of azithromycin and rifabutin as measured by changes in the plasma concentration-time curve (AUC) when these drugs are taken concomitantly. ORIGINAL PRIMARY: To gain preliminary information about the safety and tolerance of clarithromycin and azithromycin in combination with rifabutin (three potential agents against Mycobacterium avium-intracellulare) in HIV-infected patients with CD4 counts \< 200 cells/mm3. ORIGINAL SECONDARY: To determine whether there is an effect on the pharmacokinetics of the macrolide antibiotics or rifabutin when these drugs are taken concomitantly. To monitor the effect of rifabutin therapy on dapsone serum levels in patients taking dapsone for PCP prophylaxis. To monitor the effect of macrolide/rifabutin combination therapies on AZT or ddI serum levels. Two new macrolide antibiotics, clarithromycin and azithromycin, and rifabutin (a rifamycin derivative) have all demonstrated in vitro and in vivo activity against Mycobacterium avium-intracellulare, a common systemic bacterial infection complicating AIDS. Further information is needed, however, regarding the clinical and pharmacokinetic interaction of these drugs used in combination.

Two new macrolide antibiotics, clarithromycin and azithromycin, and rifabutin (a rifamycin derivative) have all demonstrated in vitro and in vivo activity against Mycobacterium avium-intracellulare, a common systemic bacterial infection complicating AIDS. Further information is needed, however, regarding the clinical and pharmacokinetic interaction of these drugs used in combination. AMENDED 03/10/94 (Part B): Approximately 38 HIV-infected or uninfected subjects are randomized to receive azithromycin or rifabutin (Groups 3 and 4) daily for 14 days, followed by a combination regimen of both drugs for 4 additional weeks. Patients are followed weekly. Pharmacokinetic sampling will be performed on days 14, 15, and 42-45. ORIGINAL: Sixty-eight patients are randomly assigned to one of four groups (17 patients per group). They receive either clarithromycin or azithromycin in combination with rifabutin on one of two different dosing schedules. Patients receive medication for 6 weeks and undergo follow-up weekly during drug administration and at week 8.