TABLE 3

Final population PK model parameter estimates and bootstrap results

Population PK parameteraFinal modelBootstrap
Estimate%SEbMedian95% CIc
CLtypical for wt 2.9 kg, PMA 39 wks, Cr 0.4 mg/dl (liters/h)d,e0.27623.10.2760.192–0.459
    TM5034.810.534.929.9.5–44.2
    Hill4.5316.54.463.47–6.35
    Exponent for Cr effect0.26726.00.2670.134–0.392
Vtypical (liters)f1.751.51.741.70–1.79
Interindividual variability
    CL (%CV)21.617.021.618.2–25.5
    V (%CV)10.942.710.64.4–14.6
Residual variability
    Proportional (%CV)20.531.619.712.2–24.7
    Additive (SD)1.373.81.30.8–2.5
  • a CL, clearance; PMA, postmenstrual age; Cr, serum creatinine; TM50, value of PMA when clearance maturation reaches 50% of adult; Hill, slope parameter for the sigmoid Emax maturation model; V, volume of distribution; %CV, coefficient of variation × 100; SD, standard deviation.

  • b %SE, relative standard error × 100.

  • c 95% confidence interval (CI) corresponding to parameter estimate at the 2.5th and 97.5th percentiles.

  • d CL (liters/h) = 0.345 (wt/2.9 kg)0.75 × Fmat × (1/Crmg/dl)0.267.

  • e Fmat = 1/(1 + [PMAwk/TM50]−Hill).

  • f V (liters) = 1.75 (wt/2.9 kg).