Since the late 1960s,
tuberculosis has been successfully cured with
antibiotics. With the introduction of
rifampin, "short course" regimens using
isoniazid and
rifampin together with either
streptomycin,
ethambutol or
pyrazinamide, for 6-9 months, have been successfully adopted. The spread of
drug resistant M.
tuberculosis strains in large urban areas has made this armamentarium of drugs insufficient, calling for the development of new drugs. Among
rifamycin derivatives,
rifabutin is more active than
rifampin in vitro and in experimental animals, and allows sputum conversion rats of 95-100%. It is effective in treating
multidrug-resistant tuberculosis.
Rifapentine is more active than
rifampin in vitro and has a longer half-life, but it is not active against
rifampin-resistant strains.
Fluoroquinolones concentrate within macrophages, are effective against M.
tuberculosis and act synergistically with
rifampin and
isoniazid.
Ofloxacin,
ciprofloxacin,
sparfloxacin and
lomefloxacin have been evaluated as
antimycobacterial agents, and no cross-resistance with major antituberculous drugs has been found. Several other drugs, including new inhibitors of
beta-lactamase and new beta-lactamase-resistant
antibiotics, the
aminoglycoside antibiotic,
paromomycin, and the new
nitroimidazole, 2-ethyl-5-intro-2.3-dihydro imidazo-
oxazole, have been found to be active in vitro against M.
tuberculosis.