Supplementary Material #2: code for NONMEM
; Base model
$PROB BASE 1
$INPUT SIM ID TIME DOSE LWT DV
$DATA sim2.txt
$PRED
KA=EXP(THETA(1)+ETA(1))
CL=EXP(THETA(2)+ETA(2))
V1=EXP(THETA(3)+ETA(3))
Y=DOSE*KA/(V1*(KA-CL/V1))*(EXP(-TIME*CL/V1)-EXP(-TIME*KA))*(1+EPS(1))
$THETA
2.3 ;1 ~lka
-0.693 ;2 ~lCL
-1.61 ;2 ~lV
$OMEGA 0 FIX 0.1 0.1
$SIGMA 0.4
$EST METHOD=1 INTERACTION PRINT=5 NOABORT
; Covariate model
$PROB COVARIATE 1
$INPUT SIM ID TIME DOSE LWT DV
$DATA sim2.txt
$PRED
KA=EXP(THETA(1)+ETA(1))
CL=EXP(THETA(2))*(EXP(LWT)/70)**THETA(4)*EXP(ETA(2))
V1=EXP(THETA(3)+ETA(3))
Y=DOSE*KA/(V1*(KA-CL/V1))*(EXP(-TIME*CL/V1)-EXP(-TIME*KA))*(1+EPS(1))
$THETA
2.3 ;1 ~lka
-0.693 ;2 ~lCL
-1.61 ;3 ~lV
0.1 ;4 PWT
$OMEGA 0 FIX 0.1 0.1
$SIGMA 0.4
$EST METHOD=1 INTERACTION PRINT=5 NOABORT
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