Although the lower dose, given twice a day in combination with other drugs, is the standard of care in general practice, some studies had suggested that a higher dose might be more effective. In the multicenter clinical trial comparing multidrug treatment regimens for people with MAC, researchers used regimens that included clarithromycin in twice-daily doses of either the standard dose of 500 mg or a higher dose of 1000 mg. Previous studies showed that higher doses kill MAC bacteria in AIDS patients' blood more quickly and thus might have greater clinical efficacy. An interim analysis conducted several months after the study began indicated that 43 percent of the patients on the 1000 mg dose of the drug had died, compared with 22 percent of the patients receiving the 500 mg dose. The researchers immediately discontinued the clarithromycin dose comparison and began giving all patients in the study the 500 mg, twice-daily dose.
All patients also receive ethambutol, and either rifabutin or clofazamine.
Treatment often results in improvement in symptoms and clearing of bacteria from the blood. However, relapse may occur several months after treatment.