Table 2.

Parameter estimates and bootstrap results of the final model

Parameter	Unit	Final model			Bootstrap
		Estimate	RSE (%)	Shrinkage (%)	Median	95% CI
ka	1/h	0.6	Fixed	–	0.6	Fixed
CL_ENA/F	L/h	4.61	12.6	–	4.53	3.43–5.67
CL_ENAAT/F	L/h	1.55	7.1	–	1.54	1.36–1.75
Vd_ENA/F	L	4.98	18.1	–	4.68	2.83–8.32
Vd_ENAAT/F	L	34.1	15.7	–	33.66	24.45–47.14
tlag	h	0.515	2.8	–	0.515	0.195–0.731
Weight on CL_ENA/F (referenced to 5 kg)	–	0.75	Fixed	–	0.75	Fixed
Weight on CL_ENAAT/F (referenced to 5 kg)	–	0.75	Fixed	–	0.75	Fixed
Weight on Vd_ENA/F (referenced to 5 kg)	–	1	Fixed	–	1	Fixed
Weight on Vd_ENAAT/F (referenced to 5 kg)	–	1	Fixed	–	1	Fixed
Age on CL_ENAAT/F	–	0.311	29.3	–	0.316	0.092–0.553
Serum creatinine on CL_ENAAT/F	–	− 0.0141	33.3	–	− 0.0141	− 0.0288 to −  0.004
Ross score on Vd_ENAAT/F	–	− 0.15	26.3	–	− 0.149	− 0.248 to −  0.004
Interindividual variabilitya
IIV CL_ENA/F	%	65.3	30	9.7	62.6	37.7–82.7
IIV CL_ENAAT/F	%	37.7	30.1	6.5	35.6	25.4–48.7
IIV Vd_ENA/F	%	80.2	41.5	17.8	79.8	41.0–114.3
IIV Vd_ENAAT/F	%	90.4	27.9	4.9	87.5	56.1–114.9
Residual variability enalapril
Proportional errorb	%	53.5	19.9	10	52.7	39.6–64.1
Additive errorc	µg/L	1.34	23.1	10	1.27	0.56–2.09
Residual variability enalaprilat
Proportional errorb	%	39.5	11.3	9.9	39.2	33.9–44.2

CL_ENA/F, CL_ENAAT/F, V_d_ENA/F and V_d_ENAAT/F estimates are given for a patient with a body weight of 5 kg. RSE derived from the covariance matrix (R matrix). CI confidence interval, CL_ENA/F apparent clearance of enalapril, CL_ENAAT/F apparent clearance of enalaprilat, IIV interindividual variability, k_a absorption rate constant, RSE relative standard error, t_lag lag time, V_d_ENA/F apparent volume of distribution of enalapril, V_d_ENAAT/F apparent volume of distribution of enalaprilat

^aThe interindividual variability is expressed as a coefficient of variation calculated according to the equation $\sqrt{{\omega }^2}\times 100\%$, where ω² is the NONMEM^® output for the interindividual variability of the parameter estimate

^bThe proportional error is expressed as a coefficient of variation calculated according to the equation $\sqrt{{\sigma }^2}\times 100\%$, where σ² is the NONMEM^® output for the proportional error term

^cThe additive error is expressed as standard deviation calculated according to the equation $\sqrt{{\sigma }^2}$, where σ² is the NONMEM^® output for the additive error term