TABLE 2.

Base and final-model population pharmacokinetic estimates and final-model bootstrap results for ceftriaxone in elderly patients

Parametera	Value for:
	Mean base	Final model
		Mean	RSE (%)b	Median bootstrap (95% CI)
Objective function value	−195.018	−217.224		−226.335 (−255.871 to −191.59)
Structural-model parameters
CLR (liters/h per 60 ml/min)		2.125	11	2.044 (0.98 to 2.66)
CLNR (liters/h per 70 kg)		0.225	33	0.248 (0.028 to 0.667)
CL (liters/h per 70 kg)	0.279
VC (liters per 70 kg)	13.2	13.3	8	13.06 (9.27 to 16.2)
Q (liters/h per 70 kg)	4.99	4.90	34	5.16 (0.95 to 16.0)
VP (liters per 70 kg)	4.87	4.73	17	5.06 (2.87 to 7.86)
Variable-model parameters (% shrinkage)
IIV in CL	42 (8)	22 (22)	21	21 (10 to 30)
IIV in VC	25 (13)	25 (13)	15	24 (16 to 34)
r(CL, VC)	0.085	−0.177	85	−0.248 (−0.839 to 0.452)
RV (%)	16 (8)	16 (16)	15	16 (13 to 18)

^aCL_R, renal clearance—final model; CL_NR, nonrenal clearance—final model; CL, clearance—base model; V_C, central volume of distribution; Q, intercompartmental clearance; V_P, peripheral volume of distribution; IIV, interindividual variability; RV, residual variability. IIV and RV are presented as $100\times \sqrt{\text{variance estimate}}$.

^bRSE, residual standard error.