Parameter estimates of rifampin pharmacokinetics in TB-HIV-coinfected patients

ParametercEstimated valueRelative SE (%)
CLa (at 2 wk) (liters/h)12.25
Change in CL on wk 8 or at 24 wk (%)+2026
V a (liters)58.04
Ka (reference formulations, RHZE and HR1) (liters/h)1.99
Effect of formulation HR2 on Ka (%)+20.733
Effect of formulation HR3 on Ka (%)+97.819
Tlag (liters/h)0.833
F (reference formulation, RHZE and HR1)1 (fixed)
Effect of formulation HR2 on F (%)−15.247
Effect of formulation HR3 on F (%)+17.828
Proportional error (%)19.88
Additive error (mg/liter)0.6658
Between-subject variability of CLb (%CV)25.712
Between-subject variability of Vb (%CV)30.114
Between-occasion variability of Kab (%CV)50.719
Between-occasion variability of Tlagb (%CV)48.26
Between-occasion variability of Fb (%CV)36.44
  • a Allometric scaling was used for CL and V, and values are reported for an adult with an FFM of 43 kg.

  • b The between-subject and between-occasion variabilities were assumed to be log-normally distributed and are reported as approximate coefficient of variation (%CV).

  • c HR, isoniazid and rifampin fixed-dose combination; RHZE, isoniazid, rifampin, ethambutol, and pyrazinamide fixed-dose combination; Tlag, absorption lag time.