Efficacy Versus Hepatotoxicity of High-dose Rifampin, Pyrazinamide, and Moxifloxacin to Shorten Tuberculosis Therapy Duration: There Is Still Fight in the Old Warriors Yet!

Abstract

One approach that could increase the efficacy and reduce the duration of antituberculosis therapy is pharmacokinetics/pharmacodynamics-based optimization of doses. However, this could increase toxicity. We mimicked the concentration-time profiles achieved by human equivalent doses of moxifloxacin 800 mg/day, rifampin 1800 mg/day, and pyrazinamide 4000 mg/day (high-dose regimen) vs isoniazid 300 mg/day, rifampin 600 mg/day, and pyrazinamide 2000 mg/day (standard therapy) in bactericidal and sterilizing effect studies in the hollow fiber system model of tuberculosis (HFS-TB). In an intracellular Mycobacterium tuberculosis (Mtb) HFS-TB experiment, we added a 3-dimensional human organotypic liver to determine potential hepatotoxicity of the high-dose regimen, based on lactate dehydrogenase (LDH). Treatment lasted 28 days and Mtb bacterial burden was based on colony counts. We calculated the time to extinction (TTE) of the Mtb population in the HFS-TB and used morphism-based transformation and Latin hypercube sampling to identify the minimum therapy duration in patients. The kill rate of standard therapy in the bactericidal effect and sterilizing effect experiments were 0.97 (95% confidence interval [CI], .91-.99) log10 colony-forming units (CFU)/mL/day, and 0.56 (95% CI, .49-.59) log10 CFU/mL/day, respectively. The high-dose regimen's bactericidal and sterilizing effect kill rates were 0.99 (95% CI, .96-.99) log10 CFU/mL/day and 0.72 (95% CI, .56-.79) log10 CFU/mL/day, respectively. The upper confidence bound for TTE in patients was 4.5-5 months for standard therapy vs 3.7 months on the high-dose regimen. There were no differences in LDH concentrations between the 2 regimens at any time point (P > .05). The high-dose regimen may moderately shorten therapy without increased hepatotoxicity compared to standard therapy.