Table 1.

Final population pharmacokinetic parameters for trastuzumab

Parameter	Population estimate (% RSE)	Between-subject variability (CV %)	Bootstrap estimate, median (2.5, 97.5 percentile)
Bioavailability of SC regimen (−)	0.771 (1.45)	13.0	0.773 (0.747, 0.797)
First-order SC absorption rate [Ka (day−1)]	0.404 (2.92)	–	0.403 (0.381, 0.429)
Linear CL (L/day)	0.111 (10.3)	30.0	0.115 (0.094, 0.153)
V max (mg/day)	11.9 (19.9)	–	11.0 (5.2, 16.3)
Km (mg/L)	33.9 (38.6)	–	28.5 (5.69, 67.2)
V c (L)	2.91 (1.24)	19.1	2.92 (2.85, 3.00)
Q (L/day)	0.445 (10.5)	–	0.444 (0.314, 0.539)
V p (L)	3.06 (3.23)	50.4	3.08 (2.88, 3.31)
Influence of body weight on linear CL	1.04 (11.3)	–	0.998 (0.695, 1.26)
Influence of body weight on V c	0.443 (11.3)	–	0.445 (0.336, 0.535)
Influence of body weight on V p	0.500 (22.2)	–	0.481 (0.200, 0.735)
Influence of ALT on linear CL	0.144 (20.8)	–	0.136 (0.085, 0.205)
Proportional variability (%)	23.9 (3.62)	–	23.9 (23.0, 24.7)
Additive variability (µg/mL)	4.48 (21.7)	–	4.43 (3.33, 5.27)

ALT, alanine transaminase; CV, coefficient of variation; Km, concentration at which the nonlinear clearance rate is half of V _max; RSE, relative standard error; SC, subcutaneous

CL_i = 0.111 · (WT_i/68)^1.04 · (ALT_i/19)^0.144

$V_{{\text{c}}_i}=2.91·{\left({\text{WT}}_i/68\right)}^{0.443}$

$V_{{\text{p}}_{{}_i}}=3.06·{\left({\text{WT}}_i/68\right)}^{0.500}$