Effect of impaired renal function on the pharmacokinetics of coadministered cefoperazone and sulbactam

Evaluation of Piperacillin/Sulbactam, Piperacillin/Tazobactam and Cefoperazone/Sulbactam Dosages in Gram-Negative Bacterial Bloodstream Infections by Monte Carlo Simulation

The optimal regimens of piperacillin/sulbactam (PIS 2:1), piperacillin/tazobactam (PTZ 8:1), and cefoperazone/sulbactam (CSL 2:1) are not well defined in patients based on renal function. This study was conducted to identify optimal regimens of BLBLIs in these patients. The antimicrobial sensitivity test was performed by a two-fold agar dilution method. Monte Carlo simulation (MCS) was used to simulate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) for various dosing regimens in patients with different renal functions. For strains with an MIC ≤ 8/4 mg/L, PIS 4.5 g q6h achieved 99.03%PTA in the subset of patients with creatinine clearance (CrCL) > 90 mL/min. For patients with CrCL 60-90 mL/min, PIS 4.5 g q6h achieved 81.2% CFR; for those with CrCL 40-59 mL/min, PIS 4.5 g q8h achieved 80.25% CFR. However, for patients infected by ESBL-producing Enterobacteriaceae, PIS 4.5 g q6h achieved a CFR lower than 80%. For patients infected by A. baumannii with a CrCL of 31-60 mL/min, PIS 6.0 g q8h and 4.5 g q6h achieved 81.24% and 82.42% CFR, respectively. For those infected by P. aeruginosa, PIS 4.5 g q6h reached 90% CFR. PIS and PTZ achieved a similar CFR when piperacillin was at the same dose. The CFRs of CSL were much lower than those of the other two agents in Enterobacteriaceae and P. aeruginosa infections. The antibacterial spectrum of PIS is superior to that of PTZ and CSL. Higher dosages and dosing adjustment according to renal function should be considered to treat Gram-negative bacterial BSIs.

Combined PK/PD Index May Be a More Appropriate PK/PD Index for Cefoperazone/Sulbactam against Acinetobacter baumannii in Patients with Hospital-Acquired Pneumonia

Cefoperazone/sulbactam (CPZ/SUL) is a β-lactam and β-lactamase inhibitor combination therapy for the treatment of respiratory tract infections. Using data from a prospective, multiple-center, open-label clinical trial in 54 patients with hospital-acquired pneumonia or ventilator-associated pneumonia caused by multidrug-resistant Acinetobacter baumannii (Ab), we showed that a combined PK/PD index %(T > MICcpz*T > MICsul) is a more appropriate PK/PD index against Ab, compared to the PK/PD index (%T > MIC) for a single drug. For a 2 h infusion, the PK/PD cutoff of CPZ/SUL (2 g/1 g, q8h) for clinical and microbiological efficacy was 4/2 and 1/0.5 mg/L, respectively. The corresponding cumulative fraction of response was 46.5% and 25.3%, respectively. Results based on the combined PK/PD index were quite similar to that based on the joint probability of target attainment. The two drugs have interaction from the viewpoint of PK/PD. When the dose of one drug was too high, the PK/PD cutoff was often determined by another drug in which the dose was maintained. In most cases, sulbactam exerted the main effect against infection by Ab in the complex CPZ/SUL, which was similar to the literature reports. When the MIC of CPZ was 8, 16, or 32 mg/L, a CPZ/SUL 2 g/1 g (q8h), 2 g/2 g (q8h), or 2 g/2 g (q6h) (infusion was all 3 h) was recommended, respectively. A clinical efficacy and safety study to confirm simulation results is warranted.

Cefoperazone/sulbactam: New composites against multiresistant gram negative bacteria?

Sulbactam, a class A β-lactamase inhibitor, added to cefoperazone either at a fixed 8 mg/L level of sulbactam or at a level of fixed cefoperazone: sulbactam ratio (2:1) would constitute a combination form of cefoperazone/sulbactam, which has better activities against Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii than cefoperazone alone. Cefoperazone/sulbactam (1:1 or 1:2) has greater in-vitro activity against most multidrug-resistant organisms (ESBL- and AmpC-producing Enterobacteriaceae and carbapenem-resistant A. baumannii except for carbapenem-resistant P. aeruginosa) than a 2:1 ratio. However, increased sulbactam concentration may induce AmpC production. Besides, sulbactam concentration might not be readily achievable in serum if the susceptibility rates were defined by the breakpoints of higher sulbactam composites, such as ≤16/16 (1:1) or 16/32 (1:2) mg/L. Carbapenemases (KPC-, OXA-type enzymes and metallo-β-lactamases) can't be inhibited by sulbactam. Some in-vitro studies showed that increasing sulbactam composites of cefoperazone/sulbactam had no effect on carbapenem-resistant P. aeruginosa, suggesting the presence of carbapenemases or AmpC overproduction that could not be overcome by increasing sulbactam levels to recover cefoperazone activity. Sulbactam alone has good intrinsic activity against carbapenem-resistant Acinetobacter strains sometimes even in the presence of carbapenemase genes, suggesting unsteady levels of carbapenemases. In conclusion, appropriate composites of cefoperazone and β-lactamase inhibitor sulbactam may expand the clinical use if the pharmacokinetic optimization could be achieved in the human serum.

Effect of acute renal failure on the disposition of cefoperazone

The effect of acute renal failure on the disposition of cefoperazone was investigated. Rats, 3 days after uranyl nitrate treatment, were used to model acute renal failure. Although plasma-protein binding of cefoperazone decreased significantly in acute renal failure compared with control rats, the plasma clearance of total (bound plus unbound) drug after intravenous administration (50 mg kg(-1)) did not differ significantly between the two groups (5.61+/-2.37 mL min(-1) for control and 4.75+/-2.82 mL min(-1) for acute renal failure). Consequently the plasma clearance of the unbound drug in acute renal failure (6.14+/-1.16 mL min(-1)) was significantly lower than in control rats (15.6+/-3.7 mL min(-1), P < 0.025). Plasma clearance of the drug (both total and unbound) was also dependent on bile flow, and clearance of the unbound drug in acute renal failure rats was lower than in control rats with identical bile flow rates. To examine the mechanism of reduced unbound cefoperazone clearance, an in-vitro experiment using a simultaneous perfusion system of rat liver and kidney was performed. By changing perfusate plasma protein from bovine serum albumin to human serum albumin, the plasma clearance of the total cefoperazone changed to one-sixth in proportion to the unbound cefoperazone in the perfusate plasma. On the other hand, the plasma clearance of the total and unbound drug in acute renal failure rats decreased significantly compared with controls. These results demonstrate that the plasma clearance of unbound cefoperazone, which is mainly eliminated by the liver, decreased in acute renal failure in rats, probably due to changes in hepatic transport.