Table 1.
Comparison of growth and pharmacodynamic killing kinetics for planktonic (extracellular liquid culture) and intracellular (macrophage) M. tuberculosis.
| Treatment | Parameter | Macrophage (intracellular Mtb) | Liquid* (extracellular Mtb) |
|---|---|---|---|
| Control | Kg max (h−1) (D.Time) | 0.033 (21.0 h) | 0.0769–0.045 (9.0 h) |
| Rifampicin | Emax (h−1) | 0.055 | 0.178 |
| EC50 (ng/mL) | 18.4 | 5.60 | |
| Ethambutol | Emax (h−1) | 0.053 | 0.142 |
| EC50 (ng/mL) | 79.5 | 264 | |
| Isoniazid | Emax (h−1) | 0.041 | 0.710, 0.055 |
| EC50 (ng/mL) | 32.1 | 790 | |
| Pyrazinamide | Emax (h−1) | 0.043 | NA |
| EC50 (ng/mL) | 45.5 | NA |
Kg max represents the maximal growth rate, E max represents the maximal possible kill rate and EC50 the concentration required to achieve 50% of the E max rate of kill. Parameters were derived from data generated from multiple independent experiments (n ≥ 3) performed in triplicate. NA, Not applicable. *For comparison, extracellular PD parameters based on in house and published values24, 25.