Determination of the minimal effective dosages of ofloxacin and sparfloxacin against M. leprae in the mouse foot pad system.

The minimal effective dosages (MEDs) of ofloxacin (OFLO) and sparfloxacin (SPFX) against 10 isolates of Mycobacterium leprae were measured in the mouse foot pad system. The drugs were administered either by gavage or by incorporation into the mouse diet in a range of concentrations. The results demonstrated that the MEDs of OFLO were 4 to 5 times higher than those of SPFX, thus confirming that, on a weight-to-weight basis, the anti-M. leprae activity of SPFX was significantly greater than that of OFLO. The MEDs of OFLO/SPFX measured by gavage were 20 times lower than those measured by incorporating the drug into the mouse diet.