Zithromax Indications & Dosage

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Zithromax - Indications & Dosage [Azithromycin]

Cumulative Incidence Rate, %: Rifabutin (n= 223)
Month MAC Free and Alive MAC Adverse Experience Lost to Follow-up
6 83.4 7.2 8.1 1.3
12 60.1 15.2 16.1 8.5
18 40.8 21.5 24.2 13.5
Cumulative Incidence Rate, %: Azithromycin (n= 223)
Month MAC Free and Alive MAC Adverse Experience Lost to Follow-up
6 85.2 3.6 5.8 5.4
12 65.5 7.6 16.1 10.8
18 45.3 12.1 23.8 18.8
Cumulative Incidence Rate, %: Azithromycin/ Rifabutin Combination (n= 218)
Month MAC Free and Alive MAC Adverse Experience Lost to Follow-up
6 89.4 1.8 5.5 3.2
12 71.6 2.8 15.1 10.6
18 49.1 6.4 29.4 15.1

Comparing the cumulative one year incidence rates, azithromycin monotherapy is at least as effective as rifabutin monotherapy. The difference (rifabutin- azithromycin) in the one year rates (7.6%) is statistically significant (p= 0.022) with an adjusted 95% confidence interval (0.9%, 14.3%). Additionally, azithromycin/ rifabutin combination therapy is more effective than rifabutin alone. The difference (rifabutin- azithromycin/ rifabutin) in the cumulative one year incidence rates (12.5%) is statistically significant (p< 0.001) with an adjusted 95% confidence interval of (6.6%, 18.4%).

The comparable number of patients experiencing adverse events and the fewer number of patients lost to follow-up on rifabutin should be taken into account when interpreting the significance of this difference.
In Study 174, sensitivity testing 5 was performed on all available MAC isolates from subjects randomized to either azithromycin, rifabutin or the combination. The distribution of MIC values for azithromycin from susceptibility testing of the breakthrough isolates was similar between study arms. As the efficacy of azithromycin in the treatment of disseminated MAC has not been established, the clinical relevance of these in vitro MICs as an indicator of susceptibility or resistance is not known.