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

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.