A Randomized, Double-Blind Trial Comparing Azithromycin and Clarithromycin in the Treatment of Disseminated Mycobacterium avium Infection in Patients with Human Immunodeficiency Virus [Dunne M, et al. CID 2000;31:1245]: This is a Pfizer-sponsored trial of 246 patients with disseminated MAC randomized to receive: 1) azithromycin - 250 mg/day; 2) azithromycin - 600 mg qd; or 3) clarithromycin - 500 mg bid. Each was combined with ethambutol, with evaluation over 24 weeks. The low dose azithromycin arm was discontinued when an interim analysis showed lower rates of negative blood cultures. The results of the study are shown in the following table:

Comment: This is a multicenter study done in 1994-98, so that it covered the transition period from hapless ART to HAART. The study affirms prior observations indicating that disseminated MAC occurs primarily in patients with highly advanced HIV infection (mean baseline CD4 count of 10/mm³). Most had not received MAC prophylaxis, and the prognosis for survival was poor (>60% died within 24 weeks of enrollment). The results with the two macrolides appeared comparable in terms of number with negative cultures at 24 weeks, frequency of relapse, mortality, and side effects. These results are in contrast with the VA cooperative research study, which showed clarithromycin to be superior to azithromycin based on the number with negative blood cultures at 16 weeks [CID 1998;27:1278]. The authors conclude that this difference in the VA study may have been erroneous due to the small sample size of 49 participants. Possible advantages of azithromycin include the reduced frequency of macrolide resistance with relapse and the potential ability to add rifabutin.
posted 12/27/2000

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