TABLE 4.
Pharmacokinetics, elimination constant, and half-life of the different β-lactam antibiotics and measured creatinine clearance
| Parametera | Median value for the parameter (IQR)b |
|||
|---|---|---|---|---|
| FEP (n = 11) | CAZ (n = 11) | PIP (n = 89) | MEM (n = 145) | |
| Serum concn at CT (mg/liter) | 12.7 (10.0–18.5) | 24.9 (12.8–34.1) | 35.2 (23.2–56.2) | 9.1 (6.9–12.9) |
| Serum concn at T0 (mg/liter) | 6.9 (5.0–10.9) | 16.0 (5.7–20.7) | 7.0 (2.8–22.0) | 3.3 (2.0–3.2) |
| Serum concn at T2 (mg/liter) | 40.7 (35.4–48.3) | 42.0 (31.8–59.5) | 65.0 (45.5–83.7) | 12.0 (8.6–17.5) |
| %T >4× MIC | 34.5 (28.1–42.7) | 53.4 (34.8–73.8) | 34.2 (21.5–44.5) | 46.9 (33.0–60.7) |
| mCLCR (ml/min) | 155 (140–199) | 173 (155–226) | 186 (149–249) | 179 (146–231) |
| ke (h−1) | 0.3 (0.2–0.4) | 0.2 (0.2–0.3) | 0.5 (0.3–0.7) | 0.3 (0.2–0.3) |
| Half-life (h) | 2.5 (2.0–3.0) | 3.3 (2.2–4.2) | 2.2 (1.0–1.4) | 2.7 (2.2–3.4) |
a
CT, serum concentration at optimal period of time (i.e., at 40%, 50%, or 70% of the dosage interval of MEM, TZP, or FEP/CAZ, respectively); T0, trough; T2, 2 h after onset of the β-lactam infusion; %T >4× MIC, percentage of time during which the antibiotic remains above 4× MIC; mCLCR, measured creatinine clearance; ke, elimination constant.
b
FEP, cefepime; CAZ, ceftazidime; PIP, piperacillin; MEM, meropenem; n, number of TDMs.