Table 2.
Final parameter estimates of the romiplostim pharmacodynamic model for MDS subjects
| Parameter (Units) | Population estimate [RSE (%)] | Inter-individual variability [RSE (%)] | Shrinkage (%) |
|---|---|---|---|
| k0DE (days−1) | 0.16 (2.61) | – | – |
| kCirc (days−1) | 0.57 (10.9) | 36.3 (70.9) | 30.9 |
| Circ0 (× 109 l−1)* | 23.7 (9.83) | 47.0 (29.7) | 12.4 |
| MTT (days) | 9.58 (11.5) | 44.7 (25.8) | 13.2 |
| Effect | |||
| Subpopulation 1, % | 77.7 (33.3) | – | – |
| α (day/μg) | 0.28 (4.07) | 163 (44.6) | 12.1 |
Circ0, baseline platelet count; Effect, romiplostim effect; kCirc, Elimination rate constant for platelet count; kDE, Elimination rate constant for dose; MTT, mean transit time; RSE, relative standard error; subpopulation 1, individuals with platelet response to romiplostim dosing.
Shape parameter for Box-Cox transformation (RSE) was −0.23 (50.0%). Interoccasion variability (RSE) of Effect was 84.9% (18.3%) and the associated shrinkage was 12.2. Residual variability (RSE) for subpopulation 1 was 20.4% (3.83%) for the proportional error term and 0.69 × 109 l−1 (6.6%) for the additive error term. Residual variability (RSE) for subpopulation 2 was 1.59 × 109 l−1 (7.11%) for the additive error term.