Table 2.
Typical parameter estimates (standard errors) of various structural models
| One-compartment model | |||
|---|---|---|---|
| Parameter | CCV | Additive | Combination |
| θCL (l h−1) | 0.0738 (0.00219) | 0.0888 (0.00270) | 0.0784 (0.00237) |
| θQ (l h−1) | |||
| θV1 (l) | 2.91 (0.0627) | 2.87 (0.0716) | 2.92 (0.0715) |
| θV2 (l) | |||
| θk0 (ng ml−1) | 0.162 (0.00666) | 0.366 (0.0447) | 0.186 (0.00896) |
| ωCL (%) | 26.7 | 19.4 | 27.7 |
| ωQ (%) | |||
| ωV1 (%) | 18.6 | 27.8 | 25.3 |
| ωV2 (%) | |||
| ωk0 (%) | 44.4 | 52.2 | 42.4 |
| σ1 (%) | 15.8 | 10.8 | |
| σ2 (ng ml−1) | 0.918 | 0.0647 | |
| AIC | 149 | 1341 | 40 |
| Two-compartment model | |||
| Parameter | CCV | Additive | Combination |
| θCL (l h−1) | 0.0813 (NE) | 0.0749 (0.00241) | 0.0820 (0.00232) |
| θQ (l h−1) | 0.00714 (NE) | 0.0672 (0.0113) | 0.0604 (0.00843) |
| θV1 (l) | 2.84 (NE) | 2.74 (0.0735) | 2.77 (0.0731) |
| θV2 (l) | 0.710 (NE) | 0.582 (0.0505) | 0.503 (0.0440) |
| θk0 (ng ml−1) | 0.142 (NE) | 0.104 (0.0340) | 0.169 (0.00669) |
| ωCL (%) | 30.2 | 21.8 | 27.1 |
| ωQ (%) | 73.3 | 65.6 | 87.5 |
| ωV1 (%) | 25.7 | 30.2 | 29.1 |
| ωV2 (%) | 45.6 | 32.4 | 49.4 |
| ωk0 (%) | 48.1 | 93.1 | 44.8 |
| σ1 (%) | 9.78 | 6.50 | |
| σ2 (ng ml−1) | 0.505 | 0.0645 | |
| AIC | −235 | 592 | −273 |
θ andω represent population pharmacokinetic parameter estimate and interindividual variability, respectively (CL, clearance; Q, intercompartmental clearance between central and peripheral; V1, volume of central compartment; V2, volume of peripheral compartment; k0, baseline erythropoietin level). σ1 and σ2 represent residual variability. CCV, Constant coefficient of variation model; Additive, additive error model; Combination, combination of the additive and CCV; AIC, Akaike’s information criterion; NE, not estimated.