Pharmacokinetics and pharmacodynamics of TMC207 and its N-desmethyl metabolite in a murine model of tuberculosis
Faculty of Pharmaceutical, Biomedical and Veterinary Sciences. Pharmacy
Antimicrobial agents and chemotherapy. - Washington, D.C.
, p. 1444-1451
University of Antwerp
TMC207 is a first-in-class diarylquinoline with a new mode of action against mycobacteria targeting the ATP synthase. It is metabolized to an active derivative, N-desmethyl TMC207, and both compounds are eliminated with long terminal half-lives (50 to 60 h in mice) reflecting slow release from tissues such as lung and spleen. In vitro, TMC207 is 5-fold more potent against Mycobacterium tuberculosis than N-desmethyl TMC207, and the effects of the two compounds are additive. The pharmacokinetic and pharmacodynamic (PK-PD) response was investigated in the murine model of tuberculosis (TB) infection following oral administration of different doses of TMC207 or N-desmethyl TMC207 at 5 days per week for 4 weeks starting the day after intravenous infection with M. tuberculosis and following administration of different doses of TMC207 at various dosing frequencies for 6 weeks starting 2 weeks after infection. Upon administration of N-desmethyl TMC207, maximum plasma concentration (Cmax), area under the plasma concentration-time curve from time zero to 168 h postdose (AUC168h), and minimum plasma concentration (Cmin) were approximately dose proportional between 8 and 64 mg/kg, and the lung CFU counts were strongly correlated with these pharmacokinetic parameters using an inhibitory sigmoid maximum effect (Emax) model. Administration of the highest dose (64 mg/kg) produced a 4.0-log10 reduction of the bacillary load at an average exposure (average concentration [Cavg] or AUC168h divided by 168) of 2.7 μg/ml. Upon administration of the highest dose of TMC207 (50 mg/kg) 5 days per week for 4 weeks, the total reduction of the bacillary load was 4.7 log10. TMC207 was estimated to contribute to a 1.8-log10 reduction and its corresponding exposure (Cavg) was 0.5 μg/ml. Optimal bactericidal activity with N-desmethyl TMC207 was reached at a high exposure compared to that achieved in humans, suggesting a minor contribution of the metabolite to the overall bactericidal activity in TB-infected patients treated with TMC207. Following administration of TMC207 at a total weekly dose of 15, 30, or 60 mg/kg fractionated for either 5 days per week, twice weekly, or once weekly, the bactericidal activity was correlated to the total weekly dose and was not influenced by the frequency of administration. Exposures (AUC168h) to TMC207 and N-desmethyl TMC207 mirrored this dose response, indicating that the bactericidal activity of TMC207 is concentration dependent and that AUC is the main PK-PD driver on which dose optimization should be based for dosing frequencies up to once weekly. The PK-PD profile supports intermittent administration of TMC207, in agreement with its slow release from tissues.