Table 2:

Final PK parameter estimates for isoniazid

Parameter	Typical Value (95% CIa)	Variabilityb, %CV (95% CIa)
CLintc (L/h) NAT2 Rapid	72.3 (61.5 – 86.7)	69.2 (64.2 – 74.2)*
CLintc (L/h) NAT2 Intermediate	38.5 (34.6 – 43.2)
CLintc (L/h) NAT2 Slow	14.5 (13.1 – 16.0)
Vcd (L)	37.6 (33.9 – 40.7)
Vpd (L)	13.3 (10.5 – 16.9)
Q/Fc (L/h)	3.32 (2.53 – 4.54)
ka (1/h)	2.69 (1.91 – 3.51)	145 (116 – 172)#
MTT (h)	0.342 (0.209 – 0.459)	116 (98.7 – 150)#
NN	48.4 (22.2 – 83.8)
QHc (L/h)	90 FIXED
fu (%)	95 FIXED
Prehepatic relative bioavailability	1 FIXED	12.3 (8.20 – 15.7)#
Proportional error (%)	13.2 (11.3 – 15.3)
Additive error (mg/L)	0.0378 (0.0335 −0.0449)
Pregnancy effect on CL (%)	+26.2 (19.8 – 33.2)

Abbreviations: CL_int clearance intrinsic; V_c apparent central volume of distribution for INH; V_P apparent peripheral volume of distribution for INH; Q/F apparent intercompartmental clearance for INH; K_a first-order rate constant of INH absorption; MTT absorption mean transit time; NN Number of absorption transit compartment; Q_H blood liver flow⁴⁰; fu unbound fraction of isoniazid in plasma⁵⁰.

^a95% confidence intervals (CIs) were obtained with the SIR procedure

^bVariability was modelled with log-normal distribution and is presented as an approximate percentage CV.

^cClearance parameters are allometrically scaled based on fat-free mass (typical value reported for 39 kg which was the median fat-free mass weight of the study population)

^dVolume pf distribution parameters are scaled based on weight (typical value reported for 67 kg which was the median weight of the study population).

^*Between subject variability.

^#Between occasion variability