Table 2.
Agreement between measured and predicted unbound concentration of ceftriaxone.
| CEFu Predicted mg/L, Median (IQR) | fu % Predicted, Median (IQR) | Bias mg/L, Median (IQR) | Relative Bias, % of CEFu, Median (IQR) | Relative RMSE, % of CEFu | p-Value b | |
|---|---|---|---|---|---|---|
| Fixed average protein binding | 8.3 (3.4–13.9) | 10.5 a | 5.6 (0.6–12) | 38.2 (19.2–50.6) | 86.1 | <0.0001 |
| Predicted saturable concentration-dependent protein binding, Equation (4) | 5 (1.8–10) | 6.3 (5.5–7.6) | 8.4 (2.2–15.7) | 59.2 (50.9–68) | 89 | <0.0001 |
| Predicted protein binding, present study, Equation (2) | 15.5 (4.2–30.4) | 17.9 (12.3–22.6) | 0.05 (−0.8–1.1) | 0.4 (−5.8–12.6) | 14.2 | 0.627 |
| Predicted protein binding, Bos | 21.8 (3.5–62.1) | 28.2 (11.7–45.3) | −6.2 (−35.9–0.1) | −35.9 (−143.7–4.8) | 195.3 | <0.0001 |
| Predicted protein binding, Leegwater | 11.5 (3.2–33.4) | 14.7 (10–25.2) | 0.3 (−10.1–1.5) | 10.2 (−49.5–29.3) | 109.2 | 0.350 |
CEFu: unbound ceftriaxone concentration; fu: unbound ceftriaxone fraction; 100% fT>MIC: free concentration above the minimum inhibitory concentration over the whole dosing interval (100%); 100% fT4x>MIC: free concentration above 4 times the minimum inhibitory concentration over the whole dosing interval (100%); IQR: interquartile range. a no median (IQR) due to a fixed protein binding coefficient; b null hypothesis = difference between CEFu measured and CEFu predicted is equal to 0.