Pharmacokinetic disposition and bactericidal activities of cefepime, ceftazidime, and cefoperazone in serum and blister fluid

Clinical Pharmacokinetics and Pharmacodynamics of Cefepime

Cefepime is a broad-spectrum fourth-generation cephalosporin with activity against Gram-positive and Gram-negative pathogens. It is generally administered as an infusion over 30-60 min or as a prolonged infusion with infusion times from 3 h to continuous administration. Cefepime is widely distributed in biological fluids and tissues with an average volume of distribution of ~ 0.2 L/kg in healthy adults with normal renal function. Protein binding is relatively low (20%), and elimination is mainly renal. About 85% of the dose is excreted unchanged in the urine, with an elimination half-life of 2-2.3 h. The pharmacokinetics of cefepime is altered under certain pathophysiological conditions, resulting in high inter-individual variability in cefepime volume of distribution and clearance, which poses challenges for population dosing approaches. Consequently, therapeutic drug monitoring of cefepime may be beneficial in certain patients including those who are critically ill, have life-threatening infections, or are infected with more resistant pathogens. Cefepime is generally safe and efficacious, with a goal exposure target of 70% time of the free drug concentration over the minimum inhibitory concentration for clinical efficacy. In recent years, reports of neurotoxicity have increased, specifically in patients with impaired renal function. This review summarizes the pharmacokinetics, pharmacodynamics, and toxicodynamics of cefepime contemporarily in the setting of increasing cefepime exposures. We explore the potential benefits of extended or continuous infusions and therapeutic drug monitoring in special populations.

An Overview of the Protein Binding of Cephalosporins in Human Body Fluids: A Systematic Review

Introduction: Protein binding can diminish the pharmacological effect of beta-lactam antibiotics. Only the free fraction has an antibacterial effect. The aim of this systematic literature review was to give an overview of the current knowledge of protein binding of cephalosporins in human body fluids as well as to describe patient characteristics influencing the level of protein binding.

Method: A systematic literature search was performed in Embase, Medline ALL, Web of Science Core Collection and the Cochrane Central Register of Controlled Trials with the following search terms: “protein binding,” “beta-lactam antibiotic,” and “body fluid.” Only studies were included where protein binding was measured in humans in vivo.

Results: The majority of studies reporting protein binding were performed in serum or plasma. Other fluids included pericardial fluid, blister fluid, bronchial secretion, pleural exudate, wound exudate, cerebrospinal fluid, dialysate, and peritoneal fluid. Protein binding differs between diverse cephalosporins and between different patient categories. For cefazolin, ceftriaxone, cefpiramide, and cefonicid a non-linear pattern in protein binding in serum or plasma was described. Several patient characteristics were associated with low serum albumin concentrations and were found to have lower protein binding compared to healthy volunteers. This was for critically ill patients, dialysis patients, and patients undergoing cardiopulmonary bypass during surgery. While mean/median percentages of protein binding are lower in these patient groups, individual values may vary considerably. Age is not likely to influence protein binding by itself, however limited data suggest that lower protein binding in newborns. Obesity was not correlated with altered protein binding.

Discussion/Conclusion: Conclusions on protein binding in other body fluids than blood cannot be drawn due to the scarcity of data. In serum and plasma, there is a large variability in protein binding per cephalosporin and between different categories of patients. Several characteristics were identified which lead to a lower protein binding. The finding that some of the cephalosporins display a non-linear pattern of protein binding makes it even more difficult to predict the unbound concentrations in individual patients. Taken all these factors, it is recommended to measure unbound concentrations to optimize antibiotic exposure in individual patients.

Systematic Review Registration: PROSPERO, identifier (CRD42021252776).

Cefepime versus ceftazidime: considerations for empirical use in critically ill patients

Sepsis and nosocomial infections continue to be a significant problem in intensive care, contributing heavily to mortality and prolonged hospital stay. Early and appropriate antibiotic therapy is critical for optimising outcomes. However, the emergence of highly resistant bacteria, coupled with reduced development of novel antibiotics, means that there is a real threat of development of untreatable nosocomial infections. Cefepime and ceftazidime are broad-spectrum cephalosporins that are widely used to treat Gram-negative nosocomial infections in critically ill patients. Available data suggest that cefepime may have advantages over ceftazidime owing to a broader spectrum of activity and reduced potential for development of bacterial resistance. However, whether either of these agents is superior can only be determined by a head-to-head study evaluating clinical and bacteriological outcomes. Such a study to determine whether apparent differences translate into clinically relevant differences in outcome is indicated.

Cefepime monotherapy for treatment of febrile neutropenia in children

AIM

Empirical therapy for children with febrile neutropenia has traditionally consisted of combination antibiotics, usually a beta-lactam and an aminoglycoside. However, recent trends and international guidelines have now made monotherapy a feasible option in the management of this group of patients. We prospectively evaluated the efficacy and safety of cefepime monotherapy in our population of paediatric cancer patients with febrile neutropenia.

METHODS

An audit was performed on children aged 16 years and younger presenting with fever and neutropenia who were managed with empirical single-agent cefepime. The patients were analysed for clinical outcome, documented infections and side-effects of the study drug. Success was defined as clinical improvement without treatment modification. Death or any change to the empirical antibiotic was considered as failure.

RESULTS

In this study 79 children (median age 5.2 years) with 133 episodes of febrile neutropenia were prospectively studied between August 2004 and August 2005. A microbiologically documented infection was seen in 26 episodes. The success rate of cefepime monotherapy was 60%. The rate of survival through neutropenia (with or without modification) was 98%. No significant adverse effects were seen.

CONCLUSION

Cefepime monotherapy is a safe and feasible option for treatment of childhood cancer patients with febrile neutropenia.

Pharmacokinetics of cefepime administered by i.v. and i.m. routes to ewes

The pharmacokinetics of cefepime were studied following i.v. and i.m. administration of 20 mg/kg in 10 ewes. Following i.v. administration of a single dose, the plasma concentration-time curves of cefepime were best fitted using a two-compartment open model. The elimination half-life (t(1/2beta)) was 1.76 +/- 0.07 h, volume of distribution at steady-state [V(d(ss))] was 0.32 +/- 0.01 L/kg and total body clearance (Cl(B)) was 2.37 +/- 0.05 mL/min.kg. Following i.m. administration, the drug was rapidly absorbed with an absorption half-life (t(1/2ab)) of 0.49 +/- 0.05 h, maximum plasma concentration (Cmax) of 31.9 +/- 1.5 mug/mL was attained at (tmax) 1.1 +/- 0.2 h and the drug was eliminated with an elimination half-life (t(1/2el)) of 2.06 +/- 0.11 h. The systemic bioavailability (F) after i.m. administration of cefepime was 86.8 +/- 7.5%. The extent of plasma protein binding measured in vitro was 14.8 +/- 0.54%. The drug was detected in urine for 36 h postadministration by both routes.

Population pharmacokinetics of cefepime in the neonate

Newborn infants cared for in neonatal intensive care units may develop nosocomial infections. Cefepime, a "fourth-generation" cephalosporin (i.e., with activity against virtually all of the chromosomal-beta-lactamase-producing and many extended-spectrum-beta-lactamase-producing organisms), provides excellent activity against many gram-negative pathogens resistant to expanded-spectrum cephalosporins currently used to treat neonatal infections. The purpose of this study was to determine the pharmacokinetics of cefepime in this population to optimize dosing and minimize potential adverse events. Premature and term infants <4 months of age hospitalized in two neonatal intensive care units were studied. Limited pharmacokinetic (PK) sampling occurred following a dose of cefepime at 50 mg/kg of body weight infused over 30 min. Population pharmacokinetic parameters were determined using the program NONMEM. Fifty-five infants were enrolled. Their average (+/- standard deviation) gestational age at birth was 30.5 +/- 5.3 weeks, and their average postnatal age at PK evaluation was 14.5 +/- 14.7 days. In the final PK model, cefepime clearance (CL) was strongly associated with serum creatinine (SCr) (CL [ml/min/kg] = 0.26 + 0.59/SCr). The volume of distribution for infants with a postconceptional age of <30 weeks was larger than that for infants with a postconceptional age of >30 weeks (0.51 versus 0.39 liter/kg, respectively). The Bayesian analysis-predicted cefepime trough concentration at a dose of 50 mg/kg every 12 h for infants < or = 14 days of age was 29.9 +/- 16.6 microg/ml. Cefepime, dosed at 30 mg/kg/dose every 12 h for infants less than 14 days of age, regardless of gestational age, should provide antibiotic exposure equivalent to or greater than 50 mg/kg every 8 h in older infants and children.

Cefepime and continuous renal replacement therapy (CRRT): In vitro permeability of two CRRT membranes and pharmacokinetics in four critically ill patients

BACKGROUND

Cefepime is a fourth-generation cephalosporin with a broad spectrum of antimicrobial activity against gram-positive and gram-negative micro-organisms. It is a useful option for treating infections in critically ill patients in intensive care due to its high degree of activity and its tolerability.

OBJECTIVE

The aim of this study was to characterize in vitro the permeability to cefepime of 2 membranes frequently used in continuous renal replacement therapies (CRRTs). An in vivo study was also carried out to determine the pharmacokinetics of cefepime in critically ill patients undergoing CRRT.

METHODS

In vitro procedures were conducted in 3 different fluids using polyacrylonitrile (AN69) or polysulfone (PS) membranes. Continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis (CVVHD) were simulated. Four male patients undergoing CVVH or continuous venovenous hemodiafiltration, who received 2000 mg of cefepime intravenously every 8 hours, entered the in vivo study. Prefilter and ultrafiltrate samples were collected, and concentrations of cefepime were measured using high-performance liquid chromatography. The sieving coefficient (Sc), defined as the fraction of drug eliminated across the membrane, and the saturation coefficient (Sa), defined as the fraction of drug diffused through the membrane to the dialysate fluid, were analyzed. Pharmacokinetic parameters were determined according to a noncompartmental analysis.

RESULTS

The patients ranged in age from 18 to 75 years and weighed from 65 to 80 kg. By analyzing Sc and Sa values in the in vitro procedures, no differences were detected in the permeability of AN69 or PS membranes to cefepime in CVVH or CVVHD. Sc/Sa values were between 0.93 and 1.03 in Ringer's lactate and in bovine albumin-containing Ringer's lactate samples, but Sc/Sa values were lower in plasma samples (0.82-0.95). In the in vivo portion of the study, the patients' mean (SD) Sc/Sa value was 0.76 (0.21) and correlated well with the fraction unbound to proteins (0.79 [0.09]). Clearance by CRRT (mean [SD]) was 29.0 (16.8)% of the total clearance. Serum elimination t(1/2) was 4.6 (0.9) hours, and the volume of distribution at steady state was 0.6 (0.3) L/kg (mean [SD] values).

CONCLUSIONS

Cefepime was significantly removed by CRRT. No significant differences were found in the Sc or Sa of cefepime between AN69 and PS membranes used in the CVVH or CVVHD procedures. The clearance of cefepime by CRRT must be considered when dosing critically ill patients.

Disposition kinetics, bioavailability and renal clearance of cefepime in calves

The pharmacokinetics of cefepime were studied following intravenous and intramuscular administration of 6.5 mg/kg in four female Friesian calves. Following single intravenous administration, the serum concentration-time curves of cefepime were best fitted using a two-compartment open model. The elimination half-life (t(1/2)beta) was 2.38+/-0.16 h, volume of distribution at steady state (Vdss) was 0.21 +/- 0.01 L/kg, and total body clearance (ClB) was 1.1 +/- 0.08 ml/min per kg. Following intramuscular administration, the drug was rapidly absorbed with an absorption half-life (t(1/2)ab) of 0.29+/-0.02 h; maximum serum concentration (Cmax) of 21.7 +/- 1.1 microg/ml was attained after (Tmax) 1.1 +/- 0.08 h; and the drug was eliminated with an elimination half-life (t(1/2)el) of 3.02 +/- 0.18 h. The systemic bioavailability (F) after intramuscular administration of cefepime in calves was 95.7% +/- 7.44%. The in vitro serum protein-binding tendency was 10.5-16.7%. Following administration by both routes, the drug was excreted in high concentrations in urine for 24 h post administration.

Beta-lactam antibiotics: newer formulations and newer agents

beta-Lactam antibiotics share a common structure and mechanism of action, although they differ in their spectrum of antimicrobial activity and utility in treating different infections. The current classes include the penicillins, the penicillinase-resistant penicillins, the extended- spectrum penicillins, the cephalosporins, the carbapenems, and the monobactams. This article discusses some of the newest beta-lactams available for use in the United States: ertapenem, cefditoren, and cefepime. A new formulation of amoxicillin-clavulanate, which contains higher doses of amoxicillin, is also discussed.

A randomized trial of cefepime and ceftazidime for the treatment of community-acquired pneumonia

We compared the effectiveness and safety of ceftazidime and cefepime in hospitalized patients with community-acquired pneumonia. The 148 enrolled patients received 2 g ceftazidime three times daily or 2 g cefepime twice daily. The clinical success rate was the same for both drugs. Even the microbiological effectiveness was similar. Both drug regimens were well tolerated. We conclude that 2 g ceftazidime three times daily were as effective as 2 g cefepime twice daily for the treatment of community-acquired pneumonia in hospitalized patients. The cost of ceftazidime treatment was, however, higher than the cost of cefepime treatment.

Rapid high-performance liquid chromatographic determination of cefepime in human plasma

A simple, rapid and reproducible high-performance liquid chromatographic method for the quantitative determination of cefepime in human plasma was developed. Ceftazidime was used as internal standard. Chromatography was performed on a reversed-phase encapped column (Hypersil BDS C18). The samples, after protein precipitation, were eluted with a mobile phase of acetonitrile-acetate buffer, pH 4 (2.8:97.2, v/v). The detection wavelength was 254 nm. The limit of quantitation of cefepime was 0.5 microgram/mL and only 0.5 mL of plasma sample was required for the determination. The average cefepime recoveries over a concentration range of 0.5-500 micrograms/mL ranged from 98 to 104%. Precision and accuracy did not exceed 5%.

Evaluation of several dosing regimens of cefepime, with various simulations of renal function, against clinical isolates of Pseudomonas aeruginosa in a pharmacodynamic infection model

The objectives of this study were as follows: (i) to examine the killing activity of 2-g doses of cefepime against two clinical isolates (mucoid and nonmucoid) of Pseudomonas aeruginosa in a pharmacodynamic in vitro infection model, (ii) to compare the percentage of time above the MIC (T > MIC) for each of the regimens against P. aeruginosa, and (iii) to evaluate the area under the bactericidal curve for each regimen. Cefepime was administered at intervals of 8, 12, and 24 h with and without tobramycin, and two different levels of renal function were simulated: normal (creatinine clearance [CLCR] = 90 ml/min) and decreased (CRCL = 60 ml/min). Also, the killing activity of cefepime with and without tobramycin was compared to the killing activity of ceftazidime (2 g every 8 h) with and without tobramycin. The T > MIC was 100% in the central chamber except for the regimen in which cefepime was administered every 12 h and the CLCR was 90 ml/min, which provided concentrations above the MIC for 92% of the dosing interval against the C31 (mucoid; MIC of cefepime, 4 microg/ml) isolate and for 75% of the interval against the C34 (nonmucoid; MIC of cefepime, 8 microg/ml) isolate. All cefepime and ceftazidime monotherapy simulations resulted in 99.9% killing of the nonmucoid isolate within 4 to 8 h and within 4 to 6 h, respectively. Against the mucoid isolate, 99.9% killing was achieved only with combination therapy. The results of this study indicate that cefepime dosed at 2 g every 12 h under conditions of normal renal function and every 24 h with decreased creatinine clearance (60 ml/min) is effective both as monotherapy and in combination therapy against a nonmucoid strain of P. aeruginosa. With cefepime MICs of 4 and 8 microg/ml, the single-agent regimens provided T > MIC values in the central chamber for 92 and >/=75% of the dosing interval against the mucoid and nonmucoid isolates, respectively. Cefepime dosed at 2 g every 12 h, with a creatinine clearance of 90 ml/min, and every 24 h, with a creatinine clearance of 60 ml/min, resulted in killing activity equivalent to that of ceftazidime dosed at 2 g every 8 h. None of the monotherapies provided adequate killing of the mucoid strain of P. aeruginosa despite drug concentrations being above the MIC for >/=92% of all dosing intervals. Finally, combination therapy with tobramycin and either cefepime or ceftazidime enhanced the killing of both the mucoid and nonmucoid P. aeruginosa isolates.

Pharmacokinetics of intravenously and intramuscularly administered cefepime in infants and children

The pharmacokinetic characteristics of cefepime were determined after first dose (n = 35) and again under steady-state conditions (n = 31) with a group of 37 infants and children. In eight subjects, a cefepime dose given by intramuscular injection was substituted for an intravenous dose, and disposition characteristics were studied again. Study subjects ranged in age from 2.1 months to 16.4 years, and all had normal renal function. Each patient received 50 mg of cefepime/kg of body weight intravenously every 8 h, up to a total maximum individual dose of 2 g. With the exception of one study patient who received a single cefepime dose for surgical prophylaxis, the patients received cefepime for 2 to 13 days. Elimination half-life (t1/2), steady-state volume of distribution, total body clearance, and renal clearance after first dose administration averaged 1.7 h, 0.35 liter/kg, and 3.1 and 1.9 ml/min/kg, respectively. Although cefepime t1/2 and mean residence time (MRT) were slightly longer for subjects <6 months of age than for older subjects, no differences in cefepime disposition characteristics between first dose and steady-state evaluations were observed. t1/2 (1.8 versus 1.9 h) and MRT (2.3 versus 3.2 h) were slightly prolonged after intramuscular administration, reflecting the influence of absorption from the intramuscular injection site on cefepime elimination. Bioavailability after intramuscular administration averaged 82% (range, 61 to 124%). Fifty-seven percent of the first dose and 88.9% of the last dose were recovered as unchanged drug in urine over the 8- and 24-h sampling periods, respectively. These pharmacokinetic data support a single cefepime dosing strategy for patients > or =2 months of age. The integration of the cefepime pharmacokinetic data generated in our study with the MICs for important pathogens responsible for infections in infants and children supports the administration of a dose of 50 mg of cefepime/kg every 12 h for patients > or =2 months of age to treat infections caused by pathogens for which cefepime MICs are < or =8 mg/liter.

The pharmacokinetic profile of a new generation of parenteral cephalosporin

Cefepime, a fourth-generation cephalosporin with activity against both gram-negative and gram-positive organisms, has been investigated in healthy subjects and in special patient populations, including the elderly and those whose ability to eliminate drugs may be compromised. This review of seven pharmacokinetic studies indicates that the pharmacokinetic disposition of cefepime, administered either intravenously or intramuscularly, is similar to that of other cephalosporins with regard to dose linearity, renal excretion, and low serum protein binding. The elimination half-life of intravenous cefepime has been found to be approximately 2 hours, and peak serum concentrations approach 82 microg/mL for a 1-g dose and 164 microg/mL for a 2-g dose. Total body clearance is approximately 120 mL/min, independent of dose, and >80% of the drug is excreted unchanged by the kidneys. Dosage adjustment is warranted for patients with renal insufficiency but not hepatic dysfunction. The pharmacokinetic disposition of cefepime is altered in the elderly but not enough to necessitate additional dosage adjustment. Tissue penetration studies indicate similarity to other cephalosporins with low protein binding.

Serum bactericidal activity of ceftazidime: continuous infusion versus intermittent injections

Since beta-lactam antibiotics have concentration-independent killing, bacterial eradication is a function of the time the serum drug concentration remains above the drug's MIC (T > MIC). We compared the serum bactericidal titers (SBTs) of ceftazidime given by continuous infusion (CI) or by intermittent bolus dosing (BD) against two clinical isolates each of Pseudomonas aeruginosa and Escherichia coli to determine if CI would allow lower daily dosing while still providing equal bactericidal activity compared with BD. This was an open-labeled, randomized, steady-state, four-way crossover study with 12 healthy volunteers. The ceftazidime regimens were 1 g every 8 h (q8h) BD, 1 g q12h BD, 3 g over 24 h CI, and 2 g over 24 h CI. The areas under the bactericidal curves were calculated by the trapezoidal rule using the reciprocal of the SBT. For all organisms the areas under the bactericidal curves for intermittent versus the CI regimens were the same for equal doses (P > 0.05). For both strains of E. coli all four regimens provided SBTs of > or = 1:2 over the dosing interval and 100% T > MIC. The 1-g q8h BD and q12h BD regimens provided T > MIC of 82 and 52%, respectively, for both P. aeruginosa isolates (MICs, 4 micrograms/ml). In comparison, the 2- and 3-g CI regimens always maintained SBTs of > or = 1:2 and T > MIC over the 24-h period as serum drug concentrations were 12.8 +/- 3.0 and 18.2 +/- 4.5 micrograms/ml, respectively. CI optimizes the pharmacodynamic and pharmacoeconomic profile of ceftazidime by providing adequate antibacterial activity over the 24-h dosing period with a reduction in the total daily dose of the antimicrobial agent.

Clinical pharmacokinetics of newer cephalosporins

Several new cephalosporins have been developed in recent years. These agents include several oral and parenteral agents with extended activity against Gram-negative pathogens. The pharmacokinetic literature for these agents is quite extensive; therefore, we have summarised this information and presented it in tabular form for critical comparison. With a few exceptions, the newer cephalosporins share similar pharmacokinetic properties. Cefixime, cefetamet pivoxil and ceftibuten differ from the others in that they exhibit nonlinear pharmacokinetic properties. The nonlinear nature of these agents is reflected by decreasing maximal concentrations with escalating doses of cefixime and cefetamet pivoxil, decreasing area under the serum concentration-time curve with increasing doses for cefixime, and a reduced bioavailability with large doses of ceftibuten. Attention to such characteristics aid the clinician in selecting appropriate dosage regimens that will optimise drug absorption. The majority of agents are primarily renally eliminated; however, renal elimination accounts for only 20% of cefixime elimination. The pharmacokinetic parameters noted for the newer cephalosporins are not influenced by multiple-dose administration, suggesting lack of drug accumulation over time. The pharmacodynamics of antimicrobials should be considered when extrapolating pharmacokinetic information into the clinical arena. In the case of the beta-lactams, the time which drug concentrations remain above some critical threshold, such as the minimal inhibitory concentration, appears to have the greatest influence on bactericidal activity. Therefore, it is important to select dosage regimens that will optimise the time serum concentrations remain above this threshold. We present an evaluation of these agents with respect to their activity against a variety of pathogens in an effort to demonstrate a pharmacokinetically-based process of antimicrobial selection.

Cefepime. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

Cefepime is a 'fourth' generation cephalosporin that has a broader spectrum of antibacterial activity than the third generation cephalosporins and is more active in vitro against Gram-positive aerobic bacteria. The fact that cefepime is stable to hydrolysis by many of the common plasmid- and chromosomally-mediated beta-lactamases, and that it is a poor inducer of type I beta-lactamases, indicates that cefepime may be useful for treatment of infections resistant to earlier cephalosporins. In comparative trials, cefepime 1 to 2 g, usually administered intravenously twice daily, was as effective as ceftazidime 1 to 2 g, usually administered 3 times daily, for treatment of bacteraemia and infections of the lower respiratory tract, urinary tract, pelvis and skin and skin structures. Furthermore, cefepime was as effective as ceftazidime and piperacillin or mezlocillin in combination with gentamicin when administered as empirical treatment for fever in patients with neutropenia. A limited number of trials have found cefepime to be as effective as cefotaxime for the treatment of gynaecological and lower respiratory tract infections. Similarly, cefepime 2 g twice daily intravenously (alone or in combination with metronidazole) was as effective as gentamicin in combination with mezlocillin or clindamycin, respectively, for the treatment of intra-abdominal infection. Cefepime has a linear pharmacokinetic profile, an elimination half-life of approximately 2 hours and is primarily excreted by renal mechanisms as unchanged drug. Cefepime has a tolerability profile similar to that of other parenteral cephalosporins; adverse events are primarily gastrointestinal in nature. A total of 1.4 and 2.9% of patients receiving cefepime < or = 2 g/day and > 2 g/day, respectively, required treatment withdrawal as a result of any adverse event. Thus, cefepime has the advantage of an improved spectrum of antibacterial activity, and is less susceptible to hydrolysis by some beta-lactamases, compared with third generation cephalosporins. Despite these advantages, cefepime has not been found to be more effective than ceftazidime and cefotaxime in clinical trials, although most trials selected patients with organisms sensitive in vitro to both comparator agents. Further trials, particularly in areas of widespread bacterial resistance, are required to confirm the positioning of cefepime for treatment of serious infection, and in particular to further explore whether its potential advantages result in clinical benefits.

Cefepime clinical pharmacokinetics

Cefepime is a new parenteral cephalosporin with antimicrobial activity similar to third-generation cephalosporins. It acts against the Enterobacteriaceae family, and Pseudomonas aeruginosa, but maintains Gram-positive activity similar to that of first- or second-generation cephalosporins. Cefepime has in vitro activity against many bacterial isolates resistant to ceftazidime and cefotaxime, is stable against chromosomally mediated beta-lactamases, demonstrates lower affinity for these enzymes and shows a high resistance to enzymatic hydrolysis. Clinical uses thus far include treatment of lower respiratory tract, intra-abdominal and urinary tract infections, skin and soft tissue infections and for prophylaxis in biliary tract and prostate surgery. Pharmacokinetic studies indicate that cefepime exhibits linear pharmacokinetic behaviour. Pharmacokinetic variables are not significantly different between single- and multiple-dose administration, indicating a lack of drug accumulation in patients with normal renal function. Cefepime is not highly bound to plasma proteins, with binding values of approximately 16 to 19%. The drug is widely distributed in various biological tissues and fluids. The primary route of elimination is from the kidneys, with over 80% of the drug recovered in the urine as unchanged drug in patients with normal renal function. Total drug clearance and renal clearance are similar to creatinine clearance, and glomerular filtration is thought to be the primary mechanism of renal excretion. The elimination half-life is approximately 2 to 2.5 h in patients. Cefepime is removed by haemodialysis (over 3h) and peritoneal dialysis (over 72h) to an appreciable extent, with 40 to 68% and 26% of the drug removed, respectively. Overall, cefepime is well tolerated by patients and no significant drug interactions have been reported to date.