Rifabutin (ansamycin LM427) for the treatment of pulmonary Mycobacterium avium complex.

During the period October 1983 through January 1988, the Centers for Disease Control (CDC) provided the experimental drug rifabutin (ansamycin LM427) to 406 patients with severe, progressive Mycobacterium avium complex pulmonary disease who had been unresponsive to standard therapy. Selected patients were randomly assigned to doses of 150, 300, or 450 mg rifabutin. Choice of companion drugs was left to the treating physicians. In the analysis of data from this program, we examined the relationship between response to treatment, as measured by bacteriologic sputum conversion, survival, weight gain, improvement in respiratory symptoms, and subjective assessment of clinical improvement, and a variety of patient and treatment variables. Although in some of the analyses a higher rifabutin dose appeared to be associated with sputum conversion, survival, and clinical improvement, the drug did not have a marked effect on outcome. The role of rifabutin in the treatment of this disease will best be assessed in a controlled clinical trial.