Experimental and clinical studies on rifampicin in treatment of leprosy.

Rifampicin showed high activity against experimental leprosy, inhibiting the multiplication of dapsone-sensitive and dapsone-resistant strains of Mycobacterium leprae in mice fed 5 mg./kg. body weight. In a formal pilot-type trial on six previously untreated patients with active lepromatous leprosy, rifampicin (600 mg. daily by mouth) was as effective as standard treatment with dapsone. Myco. leprae, however, appeared to be killed more rapidly by rifampicin than by dapsone or other antileprosy drugs so far studied. This was confirmed on a further 10 patients, including two with dapsone resistance, and from the infectivity in mice of bacilli recovered from patients during treatment with rifampicin or dapsone. These results are consistent with the bactericidal activity of rifampicin against other micro-organisms, which could be important to the chemotherapy of leprosy, since all antileprosy drugs in current use are bacteriostatic.