Clofazimine for the Treatment of Mycobacterium kansasii.

pulmonary infection is a global problem. Standard combination therapy consists of isoniazid at 300 mg/day, rifampin at 600 mg/day, and ethambutol at 15 mg/kg of body weight/day for 18 months. Coincubation of with different clofazimine concentrations over 7 days in test tubes resulted in a maximal kill (maximum effect []) of 2.03 log CFU/ml below the day 0 bacterial burden. The concentration associated with was 110 times the MIC. Next, the effects of human-like concentration-time profiles of clofazimine human-equivalent doses ranging from 0 to 200 mg daily for 21 days were examined in the hollow-fiber model of intracellular (HFS-). On day 14, when the clofazimine microbial effect was maximal, the was 2.57 log CFU/ml, while the dose associated with was 100 mg/day. However, no dose killed to levels below the day 0 bacterial burden. Thus, the antimicrobial effect of clofazimine monotherapy in the HFS- was modest. Human-equivalent concentration-time profiles of standard combination therapy and doses were used as comparators in the HFS- On day 14, standard therapy killed to a level 2.32 log CFU/ml below the day 0 bacterial burden. The effect of standard therapy was consistent with a biexponential decline, with kill rate constants of 1.85 per day (half-life = 0.37 days) and 0.06 per day (half-life = 12.76 days) ( > 0.99). This means that standard therapy would take 9.3 to 12 months to completely eliminate in the model, which is consistent with clinical observations. This observation for standard therapy means that the modest to poor effect of clofazimine on identified here is likely to be the same in the clinic.