Pharmacokinetic and pharmacodynamic profile of ceftobiprole

Ceftobiprole Medocaril: A New Fifth-Generation Cephalosporin

OBJECTIVE

The objective was to review the pharmacology, efficacy, and safety of intravenous ceftobiprole in the treatment of bloodstream infections, acute bacterial skin and skin structure infections (ABSSSIs), community-acquired pneumonia (CAP), and hospital-acquired pneumonia (HAP), or ventilator-associated pneumonia (VAP).

DATA SOURCES

PubMed and ClinicalTrials.gov were searched using the following terms: ceftobiprole, ceftobiprole medocaril, ceftobiprole medocaril sodium, Zevtera, and BAL5788.

STUDY SELECTION AND DATA EXTRACTION

Articles published in English between January 1985 and August 15, 2024, related to pharmacology, safety, efficacy, and clinical trials were reviewed.

DATA SYNTHESIS

Ceftobiprole has shown similar efficacy to comparator antibiotics in CAP, ABSSSIs, and bloodstream infections. Overall treatment success in patients with bacteremia was 69.8% and 68.7%; 91.3% and 88.1% with ABSSSIs and 86.6% and 87.4% with CAP in ceftobiprole and comparator groups, respectively. Finally, in the management of HAP and VAP, ceftobiprole was inferior in the VAP population. Ceftobiprole had a favorable safety profile with gastrointestinal adverse effects occurring more frequently than comparators.Relevance to Patient Care and Clinical Practice in Comparison to Existing Drugs:Clinicians have limited options to treat multidrug-resistant infections. Ceftobiprole has demonstrated efficacy against causative pathogens in specific infections including methicillin-resistant Staphylococcus aureus bacteremia (SAB), ABSSSI, and CAP and may be considered a viable alternative. However, ceftobiprole's impact on HAP, VAP, and febrile neutropenia needs to be further delineated.

CONCLUSION

Ceftobiprole's broad-spectrum activity makes it a viable option for treating patients hospitalized with CAP, ABSSSI, and SAB. Further studies are needed in severely ill HAP or VAP, febrile neutropenia, and pediatric patients.

Ceftobiprole in Critically Ill Patients: Proposal for New Dosage Regimens

BACKGROUND

Ceftobiprole is a broad-spectrum cephalosporin. It is currently approved for the treatment of community- and hospital-acquired pneumonia. However, the recommended dosage regimen of ceftobiprole may not be sufficient to achieve the optimal pharmacokinetic/pharmacodynamic criterion in critically ill patients. The study aimed to evaluate whether the dosage regimens proposed by the manufacturers ensure that the optimal pharmacokinetic/pharmacodynamic criterion is achieved in over 90% of critically ill patients.

METHODS

Ceftobiprole concentrations were measured in 27 patients admitted to intensive care unit. An external evaluation of published population pharmacokinetic models was performed using simulations. The model that best described the data was used to evaluate the dosage regimens proposed for intensive care unit patients by evaluating the probability of attaining the optimal pharmacokinetic/pharmacodynamic criterion (100% fT > 4 * minimum inhibitory concentration). In addition, the same model was used to suggest dosage regimen adjustments for these patients.

RESULTS

Of the 4 models evaluated, Muller's population pharmacokinetic model was selected as the best for describing the concentrations observed in 27 patients. Simulations performed with this model have shown that the manufacturer's dosing regimens do not achieve the optimal pharmacokinetic/pharmacodynamic criterion in critically ill patients. Consequently, adaptation of dosing regimens to ensure ceftobiprole effectiveness in at least 90% of the patients was proposed.

CONCLUSIONS

The proposed dosing regimens can be used to guide ceftobiprole administration in critically ill patients. However, measurement of ceftobiprole plasma concentration remains essential, at least once, to confirm patient exposure.

Current role of ceftobiprole in the treatment of hospital-acquired and community-acquired pneumonia: expert opinion based on literature and real-life experiences

INTRODUCTION

Community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP) are major global health challenges, with high morbidity and mortality rates. The increasing prevalence of multidrug-resistant (MDR) bacteria may diminish the effectiveness of standard empirical antibiotics, highlighting the need for broader-spectrum agents that target also MDR organisms.

AREAS COVERED

This review summarizes findings from a PubMed search on the use of ceftobiprole in CAP and HAP. It highlights key features of ceftobiprole, including its mechanism of action and broad spectrum of activity against multiple MDR pathogens. Clinical data from randomized controlled trials and real-world studies underscore its non-inferiority to standard treatments, with favorable safety profile and high clinical cure rates even in challenging cases.

EXPERT OPINION

Ceftobiprole represents a valid option for the patients with CAP and HAP. Its main advantages include its broad spectrum of activity, making it a valuable therapeutic choice for treating polymicrobial infections, and its favorable safety profile, which makes it a good candidate in elderly patients with multiple comorbidities and polypharmacy. Caution is advised in patients at high risk of ESBL-producing organisms or MDR Pseudomonas aeruginosa infections, where combination therapy is recommended. Moreover, therapeutic drug monitoring is recommended to improve outcomes, particularly in complex clinical conditions.

Optimizing antibiotic dosing regimens for nosocomial pneumonia: a window of opportunity for pharmacokinetic and pharmacodynamic modeling

INTRODUCTION

Determining antibiotic exposure in the lung and the threshold(s) needed for effective antibacterial killing is paramount during development of new antibiotics for the treatment of nosocomial pneumonia, as these exposures directly affect clinical outcomes and resistance development. The use of pharmacokinetic and pharmacodynamic modeling is recommended by regulatory agencies to evaluate antibiotic pulmonary exposure and optimize dosage regimen selection. This process has been implemented in newer antibiotic development.

AREAS COVERED

This review will discuss the basis for conducting pharmacokinetic and pharmacodynamic studies to support dosage regimen selection and optimization for the treatment of nosocomial pneumonia. Pharmacokinetic/pharmacodynamic data that supported recent hospital-acquired bacterial pneumonia/ventilator-associated bacterial pneumonia indications for ceftolozane/tazobactam, ceftazidime/avibactam, imipenem/cilastatin/relebactam, and cefiderocol will be reviewed.

EXPERT OPINION

Optimal drug development requires the integration of preclinical pharmacodynamic studies, healthy volunteers and ideally patient bronchoalveolar lavage pharmacokinetic studies, Monte-Carlo simulation, and clinical trials. Currently, plasma exposure has been successfully used as a surrogate for lung exposure threshold. Future studies are needed to identify the value of lung pharmacodynamic thresholds in nosocomial pneumonia antibiotic dosage optimization.

Pharmacokinetics, pharmacodynamics, and safety of single- and multiple-dose intravenous ceftobiprole in healthy Chinese participants

BACKGROUND

Ceftobiprole is a novel β-lactam cephalosporin with activity against Gram-positive and -negative bacteria. The aim of the present study was to investigate the pharmacokinetics (PK), pharmacokinetics/pharmacodynamics (PK/PD), safety and tolerance of ceftobiprole in Chinese participants, to evaluate this dosage regimen for the treatment of community-acquired pneumonia (CAP) and hospital-acquired pneumonia (HAP) in China.

METHODS

The use of ceftobiprole was investigated in a single-center, open-label, single- and multiple-dose study using 12 healthy Chinese participants (6 males and 6 females). Ceftobiprole plasma and urine concentrations were analyzed using a validated liquid chromatography-tandem mass spectrometry assay. The PK/PD characteristics of 500 mg ceftobiprole every 8 h at 1.5-, 2-, 3-, or 4-h infusion time were analyzed by Monte Carlo simulations (MCS).

RESULTS

The maximum plasma concentration of ceftobiprole was observed 2 h after dosage; its terminal half-life was about 3 h. Ceftobiprole was predominantly eliminated in urine, and the cumulative excretion in 24 h was >90%. There was no accumulation after multiple dosing. Both single and multiple doses were well tolerated, with no severe or serious adverse events (AEs). PK/PD analysis indicated that Staphylococcus pneumoniae (S. pneumoniae) and Staphylococcus aureus (S. aureus) were sensitive to ceftobiprole. About half of extended-spectrum β-lactamase (ESBL) non-producing Enterobacteriaceae are sensitive to ceftobiprole, according to PK/PD results of ceftobiprole. For Pseudomonas aeruginosa (P. aeruginosa), no regimen was found to be effective against strains.

CONCLUSIONS

The PK/PD results indicated that 500 mg ceftobiprole every 8 h at 2-h infusion time is expected to achieve good microbiological efficacy in the treatment of CAP and HAP in China.

Ceftobiprole medocaril for the treatment of community-acquired pneumonia

INTRODUCTION

Ceftobiprole is a novel broad-spectrum cephalosporin with excellent activity against a broad range of pathogens that are important in community-acquired pneumonia (CAP), including drug-resistant pneumococci, methicillin-resistant Staphylococcus aureus, and Pseudomonas aeruginosa. Areas covered: This article reviews the spectrum of activity, the main pharmacological and pharmacodynamic characteristics of ceftobiprole as well its clinical efficacy and safety in the treatment of CAP in adult patients. Expert opinion: Taking into account that the current treatment guidelines for CAP recommend the use of an adequate empirical therapy to improve its prognosis, ceftobiprole shows a profile of antimicrobial activity that would cover most etiological agents in patients with risk factors for infection caused by multidrug resistant organisms. The results of the pivotal clinical trial of patients hospitalized with CAP treated with ceftobiprole showed a high rate of clinical cure. The clinical tolerance of ceftobiprole in clinical trials was generally very good. These findings make ceftobiprole a good parenteral therapeutic alternative for the empirical treatment of CAP that requires hospitalization, especially in patients with risk factors for CAP caused by resistant microorganisms.

Monte Carlo simulation analysis of ceftobiprole, dalbavancin, daptomycin, tigecycline, linezolid and vancomycin pharmacodynamics against intensive care unit-isolated methicillin-resistant Staphylococcus aureus

The aim of the present study was to compare the potential of ceftobiprole, dalbavancin, daptomycin, tigecycline, linezolid and vancomycin to achieve their requisite pharmacokinetic/pharmacodynamic (PK/PD) targets against methicillin-resistant Staphylococcus aureus isolates collected from intensive care unit (ICU) settings. Monte Carlo simulations were carried out to simulate the PK/PD indices of the investigated antimicrobials. The probability of target attainment (PTA) was estimated at minimum inhibitory concentration values ranging from 0.03 to 32 μg/mL to define the PK/PD susceptibility breakpoints. The cumulative fraction of response (CFR) was computed using minimum inhibitory concentration data from the Canadian National Intensive Care Unit study. Analysis of the simulation results suggested the breakpoints of 4 μg/mL for ceftobiprole (500 mg/2 h t.i.d.), 0.25 μg/mL for dalbavancin (1000 mg), 0.12 μg/mL for daptomycin (4 mg/kg q.d. and 6 mg/kg q.d.) and tigecycline (50 mg b.i.d.), and 2 μg/mL for linezolid (600 mg b.i.d.) and vancomycin (1 g b.i.d. and 1.5 g b.i.d.). The estimated CFR were 100, 100, 70.6, 88.8, 96.5, 82.4, 89.4, and 98.3% for ceftobiprole, dalbavancin, daptomycin (4 mg/kg/day), daptomycin (6 mg/kg/day), linezolid, tigecycline, vancomycin (1 g b.i.d.) and vancomycin (1.5 g b.i.d.), respectively. In conclusion, ceftobiprole and dalbavancin have the highest probability of achieving their requisite PK/PD targets against methicillin-resistant Staphylococcus aureus isolated from ICU settings. The susceptibility predictions suggested a reduction of the vancomycin breakpoint to 1 μg/mL.

Ceftobiprole activity against over 60,000 clinical bacterial pathogens isolated in Europe, Turkey, and Israel from 2005 to 2010

Ceftobiprole medocaril is a newly approved drug in Europe for the treatment of hospital-acquired pneumonia (HAP) (excluding patients with ventilator-associated pneumonia but including ventilated HAP patients) and community-acquired pneumonia in adults. The aim of this study was to evaluate the in vitro antimicrobial activity of ceftobiprole against prevalent Gram-positive and -negative pathogens isolated in Europe, Turkey, and Israel during 2005 through 2010. A total of 60,084 consecutive, nonduplicate isolates from a wide variety of infections were collected from 33 medical centers. Species identification was confirmed, and all isolates were susceptibility tested using reference broth microdilution methods. Ceftobiprole had high activity against methicillin-susceptible Staphylococcus aureus (MSSA) (100.0% susceptible), methicillin-susceptible coagulase-negative staphylococci (CoNS), beta-hemolytic streptococci, and Streptococcus pneumoniae (99.3% susceptible), with MIC90 values of 0.25, 0.12, ≤ 0.06, and 0.5 μg/ml, respectively. Ceftobiprole was active against methicillin-resistant S. aureus (MRSA) (98.3% susceptible) and methicillin-resistant CoNS, having a MIC90 of 2 μg/ml. Ceftobiprole was active against Enterococcus faecalis (MIC50/90, 0.5/4 μg/ml) but not against most Enterococcus faecium isolates. Ceftobiprole was very potent against the majority of Enterobacteriaceae (87.3% susceptible), with >80% inhibited at ≤ 0.12 μg/ml. The potency of ceftobiprole against Pseudomonas aeruginosa (MIC50/90, 2/>8 μg/ml; 64.6% at MIC values of ≤ 4 μg/ml) was similar to that of ceftazidime (MIC50/90, 2/>16 μg/ml; 75.4% susceptible), but limited activity was observed against Acinetobacter spp. and Stenotrophomonas maltophilia. High activity was also observed against all Haemophilus influenzae (MIC90, ≤ 0.06 μg/ml) and Moraxella catarrhalis (MIC50/90, ≤ 0.06/0.25 μg/ml) isolates. Ceftobiprole demonstrated a wide spectrum of antimicrobial activity against this very large longitudinal sample of contemporary pathogens.

Pharmacokinetic and pharmacodynamics evaluation of ceftobiprole medocaril for the treatment of hospital-acquired pneumonia

INTRODUCTION

Ceftobiprole is a cephalosporin with activity against methicillin-resistant Staphylococcus aureus, Enterobacteriaceae, and Pseudomonas aeruginosa with a promising role in the treatment of hospital-acquired pneumonia (HAP). Cure rates, however, with ceftobiprole at the doses studied may be inferior to conventional treatment in the ventilator-acquired subset of HAP.

AREAS COVERED

Literature was sought using PubMed and through abstracts from the Interscience Conference on Antimicrobial Agents and Chemotherapy (2006 - 2012) and the European Congress of Clinical Microbiology and Infectious Diseases (2007 - 2012). The authors used the search terms "ceftobiprole," "BAL9141," "RO63-9141," "BAL5788," and 'RO5788." The article discusses the activity, mechanism of action, pharmacokinetics (PK), pharmacodynamics (PD), and clinical trials of ceftobiprole in HAP. The article also provides discussion of how PK/PD parameters play a role in the outcome of HAP treatment and how dosing in ventilator-associated pneumonia (VAP) should be reconsidered in light of altered PK/PD.

EXPERT OPINION

In patients with normal PK and non-VAP, ceftobiprole is effective for the treatment of HAP in the recommended doses, ceftobiprole is unlikely to achieve the desired PD targets when PK parameters are altered in VAP (e.g., increased volume of distribution and clearance). In these settings, off-label use at higher doses may overcome these limitations; but in the presence of alternative therapies, it cannot be currently recommended.

Synergistic activity of ceftobiprole and vancomycin in a rat model of infective endocarditis caused by methicillin-resistant and glycopeptide-intermediate Staphylococcus aureus

The therapeutic activity of ceftobiprole medocaril, the prodrug of ceftobiprole, was compared to that of vancomycin, daptomycin, and the combination of a subtherapeutic dose of ceftobiprole and vancomycin in a rat model of infective endocarditis due to methicillin-resistant Staphylococcus aureus (MRSA) (ATCC 43300) or glycopeptide-intermediate Staphylococcus aureus (GISA) (NRS4 and HIP 5836) strains. The minimum bactericidal concentrations of ceftobiprole, vancomycin, and daptomycin at bacterial cell densities similar to those encountered in the cardiac vegetation in the rat endocarditis model were 2, >64, and 8 μg/ml, respectively, for MRSA ATCC 43300 and 4, >64, and 8 μg/ml, respectively, for the GISA strain. Ceftobiprole medocaril administered in doses of 100 mg/kg of body weight given intravenously (i.v.) twice a day (BID) every 8 h (q8h) (equivalent to a human therapeutic dose of ceftobiprole [500 mg given three times a day [TID]) was the most effective monotherapy, eradicating nearly 5 log(10) CFU/g MRSA or 6 log(10) CFU/g GISA organisms from the cardiac vegetation and had the highest incidence of sterile vegetation compared to the other monotherapies in the endocarditis model. In in vitro time-kill studies, synergistic effects were observed with ceftobiprole and vancomycin on MRSA and GISA strains, and in vivo synergy was noted with combinations of subtherapeutic doses of these agents for the same strains. Additionally, sterile vegetations were achieved in 33 and 60%, respectively, of the animals infected with MRSA ATCC 43300 or GISA NRS4 receiving ceftobiprole-vancomycin combination therapy. In summary, ceftobiprole was efficacious both as monotherapy and in combination with vancomycin in treating MRSA and GISA infections in a rat infective endocarditis model and warrants further evaluation.

Newer beta-lactam antibiotics: doripenem, ceftobiprole, ceftaroline, and cefepime

This article reviews the new beta-lactam (β-lactam) antibiotics doripenem, ceftobiprole, and ceftaroline. It covers pharmacokinetic and pharmacodynamic properties, dosing, in vitro activities, safety, and clinical trial results. Doripenem (Doribax) has been approved by the US Food and Drug Administration (FDA) for the treatment of complicated intra-abdominal and urinary tract infections. Ceftaroline has received FDA approval for the treatment of skin and soft tissue infections and community acquired pneumonia. Ceftobiprole has not received FDA approval. The article also reviews recent data suggesting increased overall mortality with Cefepime (Maxipime) use compared with other beta-lactam antibiotics and the potential risk for neurotoxicity in the setting of renal failure.

Microtiter plate-based assay for inhibitors of penicillin-binding protein 2a from methicillin-resistant Staphylococcus aureus

Penicillin-binding protein 2a (PBP2a), the molecular determinant for high-level β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA), is intrinsically resistant to most β-lactam antibiotics. The development and characterization of new inhibitors targeting PBP2a would benefit from an effective and convenient assay for inhibitor binding. This study was directed toward the development of a fluorescently detected β-lactam binding assay for PBP2a from MRSA. Biotinylated ampicillin and biotinylated cephalexin were tested as tagging reagents for fluorescence detection by using a streptavidin-horseradish peroxidase conjugate. Both bound surprisingly well to PBP2a, with binding constants of 1.6 ± 0.4 μM and 13.6 ± 0.8 μM, respectively. Two forms of the assay were developed, a one-step direct competition form of the assay and a two-step indirect competition form of the assay, and both forms of the assay gave comparable results. This assay was then used to characterize PBP2a binding to ceftobiprole, which gave results consistent with previous studies of ceftobiprole-PBP2a binding. This assay was also demonstrated for screening for PBP2a inhibitors by screening a set of 13 randomly selected β-lactams for PBP2a inhibition at 750 μM. Meropenem was observed to give substantial inhibition in this screen, and a follow-up titration experiment determined its apparent K(i) to be 480 ± 70 μM. The availability of convenient and sensitive microtiter-plate based assays for the screening and characterization of PBP2a inhibitors is expected to facilitate the discovery and development of new PBP2a inhibitors for use in combating the serious public health problem posed by MRSA.

Comparative in vitro activity of ceftobiprole against Gram-positive cocci

The activity of ceftobiprole and comparator agents was evaluated against a collection of 880 isolates, comprising 200 meticillin-susceptible Staphylococcus aureus, 200 meticillin-resistant S. aureus, 180 coagulase-negative staphylococci blood isolates, 100 Streptococcuspneumoniae and 200 macrolide-resistant beta-haemolytic streptococci (100 Streptococcus pyogenes and 100 Streptococcus agalactiae). Ceftobiprole showed excellent activity against staphylococci (minimum inhibitory concentrations <or=4 microg/mL), irrespective of their susceptibility to other agents such as oxacillin, linezolid or glycopeptides. Ceftobiprole was also highly active against penicillin-resistant S. pneumoniae and macrolide-resistant beta-haemolytic streptococci, inhibiting 99.6% of all streptococci tested at <or=0.5 microg/mL. Based on these results, ceftobiprole appears to be a promising agent for the treatment of infections caused by multidrug-resistant Gram-positive pathogens.

Emerging agents to combat complicated and resistant infections: focus on ceftobiprole

Antimicrobial resistance is a global concern. Over the past few years, considerable efforts and resources have been expended to detect, monitor, and understand at the basic level the many different facets of emerging and increasing resistance. Development of new antimicrobial agents has been matched by the development of new mechanisms of resistance by bacteria. Current antibiotics act at a variety of sites within the target bacteria, including the cross-linking enzymes in the cell wall, various ribosomal enzymes, nucleic acid polymerases, and folate synthesis. Ceftobiprole is a novel parenteral cephalosporin with high affinity for most penicillin-binding proteins, including the mecA product penicillin-binding protein 2a, rendering it active against methicillin-resistant staphylococci. Its in vitro activity against staphylococci and multiresistant pneumococci, combined with its Gram-negative spectrum comparable to that of other extended-spectrum cephalosporins, its stability against a wide range of beta-lactamases, and its pharmacokinetic and safety profiles make ceftobiprole an attractive and well tolerated new antimicrobial agent. The US Food and Drug Administration granted ceftobiprole medocaril fast-track status in 2003 for the treatment of complicated skin infections and skin structure infections due to methicillin-resistant staphylococci, and subsequently extended this to treatment of hospital-acquired pneumonia, including ventilator-associated pneumonia due to suspected or proven methicillin-resistant Staphylococcus aureus.

Newer beta-lactam antibiotics: doripenem, ceftobiprole, ceftaroline, and cefepime

This article reviews the new beta-lactam (beta-lactam) antibiotics doripenem, ceftobiprole, and ceftaroline. It covers pharmacokinetic and pharmacodynamic properties, dosing, in vitro activities, safety, and clinical trial results. Doripenem (Doribax) has been approved by the US Food and Drug Administration (FDA) for the treatment of complicated intra-abdominal and urinary tract infections. At this writing, ceftobiprole is under review by the FDA for approval based on results of phase 3 clinical trials, whereas at least one phase 3 clinical trial of ceftaroline has been completed. The article also reviews recent data suggesting increased overall mortality with Cefepime (Maxipime) use compared with other beta-lactam antibiotics and the potential risk for neurotoxicity in the setting of renal failure.

[Update on antimicrobial chemotherapy]

There is a constant need for new antibacterial agents because of the unavoidable development of bacterial resistance that follows the introduction of antibiotics in clinical practice. As observed in many fields, innovation generally comes by series. For instance, a wide variety of broad-spectrum antibacterial agents became available between the 1970s and the 1990s, such as cephalosporins, penicillin/beta-lactamase inhibitor combinations, carbapenems, and fluoroquinolones. Over the last 2 decades, the arrival of new antibacterial drugs on the market has dramatically slowed, leaving a frequent gap between isolation of resistant pathogens and effective treatment options. In fact, many pharmaceutical companies focused on the development of narrow-spectrum antibiotics targeted at multidrug-resistant Gram-positive bacteria (e.g. methicillin-resistant Staphylococcus aureus, penicillin resistant Streptococcus pneumoniae, and vancomycin-resistant Enterococcus faecium). Therefore, multidrug-resistant Gram-negative bacteria (e.g. extended-spectrum beta-lactamase-producing Enterobacteriaceae, carbapenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii) recently emerged and rapidly spread worldwide. Even if some molecules were developed, new molecules for infections caused by these multidrug-resistant Gram-negative bacteria remain remarkably scarce compared to those for Gram-positive infections. This review summarises the major microbiological, pharmacological, and clinical properties of systemic antibiotics recently marketed in France (i.e. linezolid, daptomycin, tigecycline, ertapenem, and doripenem) as well as those of antibacterial drugs currently in development (i.e. ceftobiprole, ceftaroline, dalbavancin, telavancin, oritavancin, iclaprim, and ramoplanin) or available in other countries (i.e. garenoxacin, sitafloxacin, and temocillin).

Pharmacodynamic profiling of ceftobiprole for treatment of complicated skin and skin structure infections

Ceftobiprole, a broad-spectrum cephalosporin with activity against methicillin (meticillin)-resistant staphylococci, was statistically noninferior to a combination of vancomycin plus ceftazidime in patients with complicated skin and skin structure infections (cSSSI). This analysis used data from this clinical trial to determine the relationship between therapeutic outcome and the percentage of time that the unbound ceftobiprole concentration exceeds the MIC (percent T>MIC). From the trial of ceftobiprole (500 mg every 8 h, 2-h infusion) for cSSSI due to gram-positive and/or gram-negative bacteria, data from 309 patients in the microbiological intent-to-treat analysis set with measured ceftobiprole concentrations and baseline MICs were used to assess the relationship between percent T>MIC and therapeutic outcome. Individual pharmacokinetic (PK) profiles were obtained from a three-compartment population PK model. The relationship between percent T>MIC and a clinical cure was determined. For the clinical trial dosing regimen, individual percent T>MICs were used to calculate fractional target attainment rates (TARs) for >or=30 and >or=50% T>MIC targets at various MICs. There was a statistically significant relationship between achieving a >or=30 or >or=50% T>MIC and a clinical cure (P = 0.003 and P = 0.007, respectively; Pearson's chi(2) test). The fractional TAR was greater than 90% at a MIC of <or=4 mg/liter for patients with normal renal function. A relationship between percent T>MIC and a clinical cure with ceftobiprole was demonstrated. A ceftobiprole regimen of 500 mg every 8 h as a 2-h infusion has a high probability of achieving a target of >or=30 or >or=50% T>MIC for patients with cSSSI due to gram-positive and gram-negative pathogens.