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. 2007 Apr 30;151(5):701–712. doi: 10.1038/sj.bjp.0707257

Table 3.

Population pharmacokinetic parameter estimates of the non-linear transport model of morphine in brain ECF

Parameter Estimate CV% LLCI–ULCI
Structural model
 kdiff (min−1) 0.0014 12.6 0.0010–0.0017
 keff (min−1)      
 −GF120918 0.0195 12.2 0.0149–0.0241
 +GF120918 0.0113 25.4 0.0057–0.0169
N*max (ng min−1) 0.658 26.1 0.321–0.995
C50 (ng ml−1) 9.92 71.5 −3.97–23.8
       
Interanimal variability
 ω2kdiff 0.238 56.3 −0.025–0.501
 ω2keff 0.080 36.8 0.022–0.137
 ω2keff∼ ω2keff 0.059 85.0 −0.039–0.158
       
Residual variability
 Proportional error 0.094 21.4 0.055–0.134

Abbreviations: C50, morphine blood concentration at which 50% of the maximal active influx is reached; CV%, coefficient of variation; kdiff, diffusion rate constant; ECF, extracellular fluid; keff, active efflux rate constant; LLCI, lower limit of confidence interval; N*max, maximum active influx; ULCI, upper limit of confidence interval.