Table 3.

Final parameter estimates for efavirenz

Parameter	Typical value (95% CI a )	Variability b , %CV (95% CI)
CLint c , L/hour, CYP2B6 normal	2,690 (2,300–3,030)	53.8 (48.9–59.2) e
CLint c , L/hour, CYP2B6 intermediate	1,940 (1,790–2,100)
CLint c , L/hour, CYP2B6 slow	545 (487–624)
V c d , L	135 (109–165)
V p d , L	512 (487–623)
Q/F c , L/hour	26.9 (19.8–36.5)
K a, 1/hour	1.75 Fixed	180 (114.9–227) f
MTT, hour	1.78 (1.20–2.39)	131 (103–166) f
NN	48.4 (11.3–64.7)
QH c , L/hour	90 Fixed
f u, %	0.5 Fixed
Prehepatic relative bioavailability	1 Fixed	23.2 (20.7–26.1) f
Proportional error, %	6.91 (4.72–9.45)
Additive error, mg/L	0.353 (0.303–0.408)
Pregnancy effect on CL, %	+15.9 (9.75 to 21.9)
INH effect on CL/F, L/hour, in CYP2B6 fast metabolizers, %	−6.87 (−12.1 to −1.13)
INH effect on CL/F, L/hour in CYP2B6 intermediate and slow metabolizers, %	−13.4 (−17.3 to −9.06)

%CV, percent coefficient of variation; CI, confidence interval; CL, clearance; CL_int, clearance intrinsic; f _u, unbound fraction of efavirenz in plasma; INH, isoniazid; K _a, first‐order rate constant of INH absorption; MTT, absorption mean transit time; NN, number of absorption transit compartment; Q/F, apparent intercompartmental clearance for INH; Qh, blood liver flow; V _c, apparent central volume of distribution for INH; V _p, apparent peripheral volume of distribution for INH.

The bold values represent significant covariates in the models.

^aThe 95% CIs were obtained with the Standardized Infection Ratio procedure.

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

^eBetween subject variability.

^fBetween occasion variability.