Table 4.
Predicted piperacillin–tazobactam pharmacodynamic target attainment
| Dosage regimen | Standard infusion over 30 min | Extended infusion over 3 h | Continuous infusion over 24 h | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2.25 g q6h | 3.375 g q6h | 4.5 g q6h | 6.75 g q6h | 9 g q6h | 4.5 g q6h | 6.75 g q6h | 9 g q6h | 13.5 g | 18 g | 27 g | |
| Group I (n = 12) | 1 (8.3) | 1 (8.3) | 1 (8.3) | 2 (16.7) | 4 (33.3) | 3 (25) | 5 (41.7) | 8 (66.7) | 9 (75) | 11 (92) | 12 (100) |
| Group II (n = 8) | 4 (50) | 5 (62.5) | 5 (62.5) | 7 (87.5) | 7 (87.5) | 7 (87.5) | 8 (100) | 8 (100) | 8 (100) | 8 (100) | 8 (100) |
| Group III (n = 5) | 4 (80) | 4 (80) | 4 (80)a | 5 (100) | 5 (100) | 5 (100) | 5 (100) | 5 (100) | 5 (100) | 5 (100) | 5 (100) |
| Group IV (n = 3) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) | 3 (100) |
Values represent number (percent) of patients in each group meeting the target (100% fT > 16/4 mg/L) at each theoretical dosing regimen using each patient’s own Kel and Vd. Bolded values represent 100% target attainment for a given dosage regimen. Patients for whom tazobactam data were missing were assumed to have met the tazobactam pharmacodynamic target and were evaluated based on piperacillin concentrations only. Group definitions by creatinine clearance were: Group I: > 80 mL/min, Group 2: 40–80 mL/min, Group III: < 40 mL/min, and Group IV: hemodialysis
CrCl creatinine clearance, fT free trough concentration, Kel elimination rate constant, Vd volume of distribution, q6h every 6 h
aThe one Group III patient not meeting the target on 4.5 g q6h had a short piperacillin half-life of 2.0 h (despite an estimated CrCl of 27 mL/min), and a large Vd of 28.8 L