USA Clears Pfizer's Zithromax For MAC

Pfizer Inc's broad-spectrum antibiotic Zithromax (azithromycin) has gained US Food and Drug Administration approval for use in the treatment of Mycobacterium avium complex, a common opportunistic infection in persons with advanced AIDS. Clinical trials have demonstrated that prophylaxis with 1,200mg, once-weekly Zithromax reduced the risk of developing MAC bacteremia and the clinical signs and symptoms associated with this.

MAC is the most common systemic bacterial infection in persons with advanced AIDS; it has been confirmed, post-mortem, in more than 50% of people with advanced HIV infection, and the US Centers for Disease Control and Prevention estimates that one in every four persons living with AIDS has disseminated MAC. Disseminated MAC infection results in symptoms that include fever, night sweats, fatigue, abdominal pain, chronic diarrhea and weight loss or "wasting."

Clinical Experience Two randomized, double-blind trials conducted in people with advanced HIV infection showed that Zithromax effectively reduced the risk of developing disseminated MAC. In one of these pivotal studies, the drug was compared to rifabutin and the combination of these two agents. In this large double-blind study, there was a statistically significant difference in favor of Zithromax in the one-year cumulative incidence rate of disseminated MAC. Moreover, Zithromax/rifabutin combination therapy was shown to be more effective than rifabutin as monotherapy.