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. 2021 Oct 26;11(1):7–19. doi: 10.1002/psp4.12728

TABLE 1.

Parameter estimates for the final population PK model

Parameter (unit) NONMEM Bootstrap
Estimate 95% CI Median 95% CI a
Fixed effect CL (L/h) 0.0159 0.0157–0.0161 0.0159 0.0156, 0.0161
V1 (L) 3.59 3.55, 3.63 3.59 3.55, 3.62
V2 (L) 6.04 5.94, 6.14 6.05 5.93, 6.17
Q (L/h) 0.0194 0.0189, 0.0199 0.0195 0.0187, 0.0202
Covariate effect
Effect of weight WT on CL 0.561 0.512, 0.610 0.561 0.512, 0.613
WT on V1 0.506 0.467, 0.545 0.505 0.465, 0.544
WT on V2 0.320 0.269, 0.371 0.319 0.263, 0.374
Effect of age Age on V2 0.207 0.139, 0.275 0.207 0.136, 0.276
Effect of race, Asian CL 0.125 0.0903, 0.160 0.125 0.0917, 0.161
V1 −0.044 −0.067, −0.020 −0.044 −0.067, −0.022
V2 −0.148 −0.176, −0.120 −0.149 −0.180, −0.116
Effect of sex, male CL 0.134 0.112, 0.156 0.135 0.111, 0.156
V1 0.146 0.128, 0.164 0.146 0.127, 0.164
V2 0.129 0.106, 0.152 0.129 0.106, 0.156
Effect of MMSEBL MMSEBL on V2 0.182 0.0963, 0.268 0.183 0.0929, 0.279
IIV b CL, % CV 21.6 21.0, 22.2 21.6 20.9, 22.2
V1, % CV 14.8 14.2, 15.4 14.8 14.2, 15.5
V2, % CV 17.0 16.2, 17.8 17.0 16.0, 17.9
Weighting on residual error, % CV 34.9 33.6, 36.2 34.6 31.5, 37.7
ρ (CL, V1) 0.378 0.352, 0.400 0.378 0.352, 0.402
ρ (CL, V2) −0.407 −0.500, −0.327 −0.408 −0.517, −0.317
ρ (V1, V2) 0.392 0.360, 0.408 0.390 0.360, 0.403
Residual error Proportional error (%) 14.8 14.6, 15.0 14.8 14.5, 15.0
Additive error (mg/L) 0.202 0.189, 0.215 0.200 0.175, 0.227

Abbreviations: CI, confidence interval; CL, clearance; CV, coefficient of variation; IIV, interindividual variability; MMSEBL, Mini‐Mental State Examination score at baseline; NONMEM, nonlinear mixed‐effect modeling software; ρ, correlation; PK, pharmacokinetic; Q, intercompartmental clearance; V1, central volume; V2, peripheral volume; WT, weight.

a

Twenty‐seven runs were skipped while calculating bootstrap summaries.

b

%CV = 100(expω21).