Biapenem

In vitro activity, pharmacodynamic profile and dose optimization of biapenem against NDM and OXA-48-like carbapenemase-producing Klebsiella pneumoniae: A multicentre study in Thailand

BACKGROUND

Biapenem (BIPM) exhibited a less efficient substrate for various metallo-β-lactamase (MBL) than other carbapenems.

OBJECTIVE

We aimed to evaluate in vitro susceptibility data of BIPM and optimal dose based on Monte Carlo simulation to extend treatment options.

METHODS

We collected 192 carbapenem-resistant Klebsiella pneumoniae (CRKP) clinical isolates from unique patients among multicentres in Thailand, from June 2019 to March 2023. BIPM disk diffusion and broth-microdilution testing were performed to obtain minimum inhibitory concentration (MIC). Each BIPM regimen was simulated using the Monte Carlo technique to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR).

RESULTS

The most common genotypes among 192 CRKP isolates were blaOXA-48 (62.3%), blaOXA-48+blaNDM (22.6%) and blaNDM (15.1%). BIPM showed 22.4 and 28.6% susceptible rate when interpreted at clinical breakpoints of 1 and 2 mg/L. The MIC50 and MIC90 of BIPM against CRKP were 8 and 32 mg/L. The BIPM dosing regimens of 300 mg q 6 h infused 6 h and 600 mg q 8 h infused 8 h met the PTA target of %fTime >MIC at 50%, 75% and 100% against isolates MICs of ≤2 mg/L. Based on CFR ≥90%, no BIPM regimens were effective against all the studied CRKP isolates.

CONCLUSION

BIPM exhibited a partially susceptible rate among the CRKP isolates in Thailand. The current suggested dose of BIPM with prolonged infusion appears appropriate regimen against CRKP MICs of ≤2 mg/L. However, the empirical use of BIPM for severe CRE infection is not recommended unless the susceptibility has been confirmed.

Population pharmacokinetics, dosing optimization and clinical outcomes of biapenem in patients with sepsis

Introduction: Biapenem is a carbapenem antibiotic widely used in Asia, can be used for the treatment of adults and children with infections due to susceptible bacteria. Although biapenem is utilized in the treatment of a diverse range of bacterial infections, current pharmacokinetic data in the context of septic populations remain limited. Consequently, our research aims to evaluate the pharmacokinetics and efficacy of biapenem within a septic population to optimize biapenem therapy. Methods: In this study, we characterized the pharmacokinetics of biapenem in septic patients using a population pharmacokinetic (PPK) approach. The clinical PK data to develop the PPK model were obtained from 317 septic patients admitted to Nanjing Drum Tower Hospital between 2018 and 2022. All patients were randomized to the modeling and validation cohorts at a 3:1 ratio, with PPK modeling and validation performed utilizing the NONMEM software. Results: The model found to best describe the available data was a two-compartment PPK model with first-order elimination characterized by the parameters clearance (CL), central volume (V1), peripheral volume (V2), and intercompartmental clearance (Q). A covariate analysis identified that creatinine clearance (CLCR) was a significant covariate influencing biapenem CL, while blood urea nitrogen (BUN) was a significant covariate influencing biapenem Q. Accoding to the clinical outcome analyses, 70% of the time that the free antimicrobial drug concentration exceeds the MIC (fT >MIC) is associated with favourable clinical outcomes. The PPK model was then used to perform Monte Carlo simulations to evaluate the probability of attaining 70% fT >MIC. Conclusions: A final PPK model of biapenem was established for patients with sepsis. The current daily dosage regimen of 1.2 g may insufficient to achieve 70% fT >MIC in septic patients. The dosage regimen of 600 mg every 6 h appears to be the optimal choice.

Simultaneous determination of five carbapenems, highly polar antibiotics, in milk by LC-MS/MS

The simultaneous determination of five carbapenems (biapenem, doripenem, ertapenem, imipenem, and meropenem) in raw and pasteurised bovine milk samples using LC-MS/MS was achieved and validated. Chromatographic separation was conducted on an InertSustain® AQ-C18 column using 0.1% formic acid in water and acetonitrile as the mobile phase. Target compounds were extracted using acetonitrile/water (20:80, v/v). After the removal of lipids with acetonitrile-saturated hexane, the dissolved protein was denatured with acetic acid. A portion of the supernatant was passed through an Oasis® PRiME HLB cartridge to remove the matrix. This novel method was validated in accordance with the Japanese validation guidelines and exhibited good trueness, ranging from 86.3% to 96.2%, using matrix-matched calibration curves. The relative standard deviation of repeatability ranged from 1.0% to 6.3%, and that of within-laboratory reproducibility ranged from 1.6% to 7.1%. The limit of quantification was 1.0 µg kg-1 for all analytes. None of the 60 milk samples commercially available in Tokyo contained any analytes. This novel method exhibited high-quality performance and can easily be implemented for the routine monitoring of carbapenems, which are highly polar antibiotics in milk.

Efficacy of Omadacycline-Containing Regimen in a Mouse Model of Pulmonary Mycobacteroides abscessus Disease

Mycobacteroides abscessus is an opportunistic pathogen in people with structural lung conditions such as bronchiectasis, chronic obstructive pulmonary disease, and cystic fibrosis. Pulmonary M. abscessus infection causes progressive symptomatic and functional decline as well as diminished lung function and is often incurable with existing antibiotics. We investigated the efficacy of a new tetracycline, omadacycline, in combination with existing antibiotics recommended to treat this indication, in a mouse model of M. abscessus lung disease. Amikacin, azithromycin, bedaquiline, biapenem, cefoxitin, clofazimine, imipenem, linezolid, and rifabutin were selected as companions to omadacycline. M. abscessus burden in the lungs of mice over a 4-week treatment duration was considered the endpoint. Omadacycline in combination with linezolid, imipenem, cefoxitin, biapenem, or rifabutin exhibited early bactericidal activity compared to any single drug. Using three M. abscessus isolates, we also determined the in vitro frequency of spontaneous resistance against omadacycline to be between 1.9 × 10-10 and 6.2 × 10-10 and the frequency of persistence against omadacycline to be between 5.3 × 10-6 and 1.3 × 10-5. Based on these findings, the combination of omadacycline and select drugs that are included in the recent treatment guidelines may exhibit improved potency to treat M. abscessus lung disease. IMPORTANCE M. abscessus disease incidence is increasing in the United States. This disease is difficult to cure with existing antibiotics. In this study, we describe the efficacy of a new tetracycline antibiotic, omadacycline, in combination with an existing antibiotic to treat this disease. A mouse model of M. abscessus lung disease was used to assess the efficacies of these experimental treatment regimens. Omadacycline in combination with select existing antibiotics exhibited bactericidal activity during the early phase of treatment.

β-Lactam potentiators to re-sensitize resistant pathogens: Discovery, development, clinical use and the way forward

β-lactam antibiotics are one of the most widely used and diverse classes of antimicrobial agents for treating both Gram-negative and Gram-positive bacterial infections. The β-lactam antibiotics, which include penicillins, cephalosporins, monobactams and carbapenems, exert their antibacterial activity by inhibiting the bacterial cell wall synthesis and have a global positive impact in treating serious bacterial infections. Today, β-lactam antibiotics are the most frequently prescribed antimicrobial across the globe. However, due to the widespread use and misapplication of β-lactam antibiotics in fields such as human medicine and animal agriculture, resistance to this superlative drug class has emerged in the majority of clinically important bacterial pathogens. This heightened antibiotic resistance prompted researchers to explore novel strategies to restore the activity of β-lactam antibiotics, which led to the discovery of β-lactamase inhibitors (BLIs) and other β-lactam potentiators. Although there are several successful β-lactam-β-lactamase inhibitor combinations in use, the emergence of novel resistance mechanisms and variants of β-lactamases have put the quest of new β-lactam potentiators beyond precedence. This review summarizes the success stories of β-lactamase inhibitors in use, prospective β-lactam potentiators in various phases of clinical trials and the different strategies used to identify novel β-lactam potentiators. Furthermore, this review discusses the various challenges in taking these β-lactam potentiators from bench to bedside and expounds other mechanisms that could be investigated to reduce the global antimicrobial resistance (AMR) burden.

A Comprehensive Overview of the Antibiotics Approved in the Last Two Decades: Retrospects and Prospects

Due to the overuse of antibiotics, bacterial resistance has markedly increased to become a global problem and a major threat to human health. Fortunately, in recent years, various new antibiotics have been developed through both improvements to traditional antibiotics and the discovery of antibiotics with novel mechanisms with the aim of addressing the decrease in the efficacy of traditional antibiotics. This manuscript reviews the antibiotics that have been approved for marketing in the last 20 years with an emphasis on the antibacterial properties, mechanisms, structure-activity relationships (SARs), and clinical safety of these antibiotics. Furthermore, the current deficiencies, opportunities for improvement, and prospects of antibiotics are thoroughly discussed to provide new insights for the design and development of safer and more potent antibiotics.

Studies on the Reactions of Biapenem with VIM Metallo β-Lactamases and the Serine β-Lactamase KPC-2

Carbapenems are important antibacterials and are both substrates and inhibitors of some β-lactamases. We report studies on the reaction of the unusual carbapenem biapenem, with the subclass B1 metallo-β-lactamases VIM-1 and VIM-2 and the class A serine-β-lactamase KPC-2. X-ray diffraction studies with VIM-2 crystals treated with biapenem reveal the opening of the β-lactam ring to form a mixture of the (2S)-imine and enamine complexed at the active site. NMR studies on the reactions of biapenem with VIM-1, VIM-2, and KPC-2 reveal the formation of hydrolysed enamine and (2R)- and (2S)-imine products. The combined results support the proposal that SBL/MBL-mediated carbapenem hydrolysis results in a mixture of tautomerizing enamine and (2R)- and (2S)-imine products, with the thermodynamically favoured (2S)-imine being the major observed species over a relatively long-time scale. The results suggest that prolonging the lifetimes of β-lactamase carbapenem complexes by optimising tautomerisation of the nascently formed enamine to the (2R)-imine and likely more stable (2S)-imine tautomer is of interest in developing improved carbapenems.

Real-world Biapenem vs. Meropenem in the treatment of severe community-acquired pneumonia in children: A propensity score matching analysis

OBJECTIVE

To compare the real-world efficacy and safety of Biapenem and Meropenem for treating severe community-acquired pneumonia (SCAP) in children.

METHODS

We retrospectively evaluated 915 children with SCAP who were treated with Biapenem or Meropenem from August 2018 to June 2022. A 1:1 propensity score matching (PSM) analysis was used to reduce the actual baseline difference between groups.

RESULTS

416 patients participated in the analysis after PSM (Biapenem: Meropenem = 1:1). For the Biapenem group and Meropenem group, the effective rates were 90.4% and 90.9%, respectively (p = 1.0) and the incidence of adverse reactions were 7.7% and 7.2%, respectively (p = 1.0). There were no statistical differences between Biapenem and Meropenem.

CONCLUSION

In general, the efficacy and safety of Biapenem are comparable to Meropenem in the treatment of children with SCAP.

Role of organic anion transporter 3 in the renal excretion of biapenem and potential drug-drug interactions

Biapenem is a carbapenem antibiotic. It is excreted predominantly through the kidney as unchanged forms. However, the molecular mechanism of renal excretion of biapenem and potential drug-drug interactions (DDIs) were still unknown. In the present study, the role of organic anion transporters (OAT) 1/3 and organic cation transporters (OCT) 2 in the renal excretion of biapenem, and the potential DDIs between biapenem and six clinical commonly prescribed antibiotics and antiviral drugs that acted as substrates or inhibitors of OAT3 were evaluated in vitro. Further, the effect of probenecid on the pharmacokinetics of biapenem was explored in the rats. We observed that biapenem could not inhibit the transport activities of OAT1 or OCT2, while mildly inhibited OAT3 (IC₅₀ >500 μM). Among the tested antibiotics and antiviral drugs, the relatively high DDI index values (maximal unbound plasma concentration over IC₅₀, I_max,u/IC₅₀) were found for piperacillin, linezolid and benzylpenicillin, which were 2.84, 1.7 and 0.62, respectively. Although probenecid had the highest DDI index (27.1) in vitro, no significant impact of it on the pharmacokinetics of biapenem was observed in the rats. Our results indicated that biapenem was primarily eliminated by the glomerular filtration, while OAT3-mediated renal tubular secretion was a minor route. Biapenem is not a clinically relevant substrate or inhibitor because of its low affinity to OAT3. According to current results, it would be safe to use biapenem with other antibiotics and antiviral drugs that acted as substrates or inhibitors of OAT3.

Repurposing Immunomodulatory Drugs to Combat Tuberculosis

Tuberculosis (TB) is an infectious disease caused by an obligate intracellular pathogen, Mycobacterium tuberculosis (M.tb) and is responsible for the maximum number of deaths due to a single infectious agent. Current therapy for TB, Directly Observed Treatment Short-course (DOTS) comprises multiple antibiotics administered in combination for 6 months, which eliminates the bacteria and prevents the emergence of drug-resistance in patients if followed as prescribed. However, due to various limitations viz., severe toxicity, low efficacy and long duration; patients struggle to comply with the prescribed therapy, which leads to the development of drug resistance (DR). The emergence of resistance to various front-line anti-TB drugs urgently require the introduction of new TB drugs, to cure DR patients and to shorten the treatment course for both drug-susceptible and resistant populations of bacteria. However, the development of a novel drug regimen involving 2-3 new and effective drugs will require approximately 20-30 years and huge expenditure, as seen during the discovery of bedaquiline and delamanid. These limitations make the field of drug-repurposing indispensable and repurposing of pre-existing drugs licensed for other diseases has tremendous scope in anti-DR-TB therapy. These repurposed drugs target multiple pathways, thus reducing the risk of development of drug resistance. In this review, we have discussed some of the repurposed drugs that have shown very promising results against TB. The list includes sulfonamides, sulfanilamide, sulfadiazine, clofazimine, linezolid, amoxicillin/clavulanic acid, carbapenems, metformin, verapamil, fluoroquinolones, statins and NSAIDs and their mechanism of action with special emphasis on their immunomodulatory effects on the host to attain both host-directed and pathogen-targeted therapy. We have also focused on the studies involving the synergistic effect of these drugs with existing TB drugs in order to translate their potential as adjunct therapies against TB.

Pharmacokinetic Drug-drug Interaction of Antibiotics Used in Sepsis Care in China

BACKGROUND

Many antibiotics have a high potential for interactions with drugs, as a perpetrator and/or victim, in critically ill patients, and particularly in sepsis patients.

METHODS

The aim of this review is to summarize the pharmacokinetic drug-drug interaction (DDI) of 45 antibiotics commonly used in sepsis care in China. Literature search was conducted to obtain human pharmacokinetics/ dispositions of the antibiotics, their interactions with drug-metabolizing enzymes or transporters, and their associated clinical drug interactions. Potential DDI is indicated by a DDI index ≥ 0.1 for inhibition or a treatedcell/ untreated-cell ratio of enzyme activity being ≥ 2 for induction.

RESULTS

The literature-mined information on human pharmacokinetics of the identified antibiotics and their potential drug interactions is summarized.

CONCLUSION

Antibiotic-perpetrated drug interactions, involving P450 enzyme inhibition, have been reported for four lipophilic antibacterials (ciprofloxacin, erythromycin, trimethoprim, and trimethoprim-sulfamethoxazole) and three antifungals (fluconazole, itraconazole, and voriconazole). In addition, seven hydrophilic antibacterials (ceftriaxone, cefamandole, piperacillin, penicillin G, amikacin, metronidazole, and linezolid) inhibit drug transporters in vitro. Despite no clinical PK drug interactions with the transporters, caution is advised in the use of these antibacterials. Eight hydrophilic antibiotics (all β-lactams; meropenem, cefotaxime, cefazolin, piperacillin, ticarcillin, penicillin G, ampicillin, and flucloxacillin), are potential victims of drug interactions due to transporter inhibition. Rifampin is reported to perpetrate drug interactions by inducing CYP3A or inhibiting OATP1B; it is also reported to be a victim of drug interactions, due to the dual inhibition of CYP3A4 and OATP1B by indinavir. In addition, three antifungals (caspofungin, itraconazole, and voriconazole) are reported to be victims of drug interactions because of P450 enzyme induction. Reports for other antibiotics acting as victims in drug interactions are scarce.

β-Lactam Combinations That Exhibit Synergy against Mycobacteroides abscessus Clinical Isolates

Mycobacteroides abscessus (Mab) is an opportunistic environmental pathogen that can cause chronic pulmonary disease in the setting of structural lung conditions such as bronchiectasis, chronic obstructive pulmonary disease, and cystic fibrosis. These infections are often incurable and associated with rapid lung function decline. Mab is naturally resistant to most of the antibiotics available today, and current treatment guidelines require at least 1 year of daily multidrug therapy, which is often ineffective and is associated with significant toxicities. β-Lactams are the most widely used class of antibiotics and have a demonstrated record of safety and tolerability. Here, using a panel of recent clinical isolates of Mab, we evaluated the in vitro activities of dual-β-lactam combinations to identify new treatments with the potential to treat infections arising from a wide range of Mab strains. The Mab clinical isolates were heterogeneous, as reflected by the diversity of their genomes and differences in their susceptibilities to various drugs. Cefoxitin and imipenem are currently the only two β-lactams included in the guidelines for treating Mab disease, yet they are not used concurrently in clinical practice. However, this dual-β-lactam combination exhibited synergy against 100% of the isolates examined (n = 21). Equally surprising is the finding that the combination of two carbapenems, doripenem and imipenem, exhibited synergy against the majority of Mab isolates. In the setting of multidrug-resistant Mab disease with few therapeutic options, these combinations may offer viable immediate treatment options with efficacy against the broad spectrum of Mab strains infecting patients today.

Microbial Natural Products in Drug Discovery

Over a long period of time, humans have explored many natural resources looking for remedies of various ailments. Traditional medicines have played an intrinsic role in human life for thousands of years, with people depending on medicinal plants and their products as dietary supplements as well as using them therapeutically for treatment of chronic disorders, such as cancer, malaria, diabetes, arthritis, inflammation, and liver and cardiac disorders. However, plant resources are not sufficient for treatment of recently emerging diseases. In addition, the seasonal availability and other political factors put constrains on some rare plant species. The actual breakthrough in drug discovery came concurrently with the discovery of penicillin from Penicillium notatum in 1929. This discovery dramatically changed the research of natural products and positioned microbial natural products as one of the most important clues in drug discovery due to availability, variability, great biodiversity, unique structures, and the bioactivities produced. The number of commercially available therapeutically active compounds from microbial sources to date exceeds those discovered from other sources. In this review, we introduce a short history of microbial drug discovery as well as certain features and recent research approaches, specifying the microbial origin, their featured molecules, and the diversity of the producing species. Moreover, we discuss some bioactivities as well as new approaches and trends in research in this field.

A mouse model of pulmonary Mycobacteroides abscessus infection

There is no preclinical mouse model to investigate pulmonary Mycobacteroides abscessus (formerly Mycobacterium abscessus) infection in an immunocompetent mouse strain, especially in the context of antibiotic testing and regimen development. We developed a mouse model of pulmonary M. abscessus infection using the aerosolized route of infection that leads to an increase in bacterial burden post- implantation and develops pathology as a result. In this mouse model, treatment with corticosteroid allows for initial proliferation and sustained M. abscessus pulmonary infection and permits evaluation of efficacies of antibiotics. Administration of corticosteroids that permitted higher levels of bacterial burden in the lungs were more likely to have pathology. Treatment of mice with antibiotics administered intranasally or subcutaneously significantly reduced lung M. abscessus burden. In addition to the reference strain, independent clinical isolates of M. abscessus also readily establish infection and proliferate in the lungs of mice in this model.

Have we realized the full potential of β-lactams for treating drug-resistant TB?

β-lactams are the most widely used antibiotics and are effective against a spectrum of pathogenic bacteria. Here, we focus on the state-of-the-art understanding of the molecular underpinnings that determine the overall efficacy of β-lactams against TB and include historical perspectives of this antibiotic class against this ancient disease. We summarize literature that describes why earlier generations of β-lactams are ineffective and the potential promise of newer β-lactams that exhibit improved efficacy against TB. Emerging evidence warrants renewed consideration of newer β-lactams in regimens for treatment of drug-resistant TB. © 2018 IUBMB Life, 70(9):881-888, 2018.

In Vitro Activity of β-Lactams in Combination with β-Lactamase Inhibitors against Mycobacterium tuberculosis Clinical Isolates

OBJECTIVES

Evaluating the activity of nineteen β-lactams in combination with different β-lactamase inhibitors to determine the most potent combination against Mycobacterium tuberculosis (MTB) in vitro.

METHODS

Drug activity was examined by drug susceptibility test with 122 clinical isolates from China. Mutations of blaC and drug targets ldtMt1 , ldtMt2 , dacB2, and crfA were analyzed by nucleotide sequencing.

RESULTS

Tebipenem (TBM) in combination with clavulanate (CLA) exhibited the highest anti-TB activity. The MIC of β-lactam antibiotics was reduced most evidently in the presence of CLA, compared to avibactam (AVI) and sulbactam (SUB). Eight polymorphism sites were identified in blaC, which were not associated with β-lactams resistance. Interestingly, one strain carrying G514A mutation in blaC was highly susceptible to β-lactams regardless of the presence of inhibitors. The transpeptidase encoding genes, ldtMt1 , ldtMt2 , and dacB2, harboured three mutations, two mutations, and one mutation, respectively, but no correlation was found between these mutations and drug resistance.

CONCLUSION

The activity of β-lactams against MTB and different synergetic effect of β-lactamase inhibitors were indicated. TBM/CLA exhibited the most activity and has a great prospect in developing novel anti-TB regimen; however, further clinical research is warranted. Moreover, the resistance to the β-lactam antibiotics might not be conferred by single target mutation in MTB and requires further studies.

In vitro and in vivo activity of biapenem against drug-susceptible and rifampicin-resistant Mycobacterium tuberculosis

Background

Biapenem, a carbapenem antibiotic, has been shown to have synergistic bactericidal anti-TB activity when combined with rifampicin both in vitro and in the mouse model of TB chemotherapy. We hypothesized that this synergy would result in biapenem/rifampicin activity against rifampicin-resistant Mycobacterium tuberculosis .

Objectives

Our objective was to evaluate the synergy of biapenem/rifampicin against both low- and high-level rifampicin-resistant strains of M. tuberculosis , in vitro and in the mouse model.

Methods

Biapenem/rifampicin activity was evaluated using three strains of M. tuberculosis : strain 115R (low-level rifampicin resistance); strain 124R (high-level rifampicin resistance); and the drug-susceptible H37Rv parent strain. Biapenem/rifampicin synergy was evaluated in vitro by chequerboard titration. In vivo , we first conducted a dose-ranging experiment with biapenem against H37Rv in the mouse model. We then evaluated biapenem/rifampicin activity in mice infected with each M. tuberculosis strain.

Results

In vitro , synergy was observed between biapenem and rifampicin against H37Rv and strain 115R. In vivo , biapenem exhibited clear dose-dependent activity against H37Rv, with all biapenem doses as active or more active than rifampicin alone. Biapenem and rifampicin had synergistic bactericidal activity against H37Rv in the mouse model; no synergy was observed in mice infected with either of the rifampicin-resistant strains. Biapenem alone was active against all three strains.

Conclusions

Our preclinical experiments indicate that biapenem has potential for use as an anti-TB drug, including for use against rifampicin-resistant TB. Thus, biapenem has promise for repurposing as a 'new' - and desperately needed - drug for the treatment of drug-resistant TB.

Evaluating biapenem dosage regimens in intensive care unit patients with Pseudomonas aeruginosa infections: a pharmacokinetic/pharmacodynamic analysis using Monte Carlo simulation

This study was conducted to identify optimal dosage regimens and estimate pharmacokinetic/pharmacodynamic (PK/PD) characteristics of short-infusion (SI) versus extended-infusion (EI) biapenem against Pseudomonas aeruginosa infections in Chinese intensive care unit (ICU) patients. A total of 85 strains of P. aeruginosa were collected, and the minimum inhibitory concentration (MIC) of biapenem was measured by the serial two-fold agar dilution method. We designed four frequently used clinical regimens: biapenem 300 mg I.V. q12h, q8h, and q6h, and 600 mg q12h. The Monte Carlo Simulation (MCS) was performed using previously published pharmacokinetic data to calculate the probability of target attainment (PTA) and the cumulative fraction of response (CFR) of these regimens as an SI (0.5 h) and an EI (1 h, 2 h, 3 h, and 4 h). For a target of 40%fT_>MIC (serum drug concentration remains above the MIC for a dosing period), none of the regimens achieved any CFRs>90% for P. aeruginosa, multidrug-resistant P. aeruginosa (MDR-PA) and even non-MDR-PA. The traditional biapenem SI regimens most commonly seen in clinical practice were insufficient in treating both MDR and non-MDR P. aeruginosa in ICU patients. However, biapenem 600 mg q12h over 2-4 h EI regimens could achieve CFR>90% with 20%fT_>MIC. Clinical trials should aim to validate the potentially greater PK/PD index with higher, more frequent doses and longer extended infusions.

Efficacy and safety of biapenem in treatment of infectious disease: a meta-analysis of randomized controlled trials

BACKGROUND

Biapenem is a parenteral carbapenem antibiotic that has powerful antibacterial activity. The aim of this study is to evaluate the efficacy and safety of biapenem for the treatment of infection diseases.

METHODS

We performed a meta-analysis of published randomized-controlled trials (RCTs) identified in Embase, PubMed, and Cochrane library that compared the efficacy and safety of biapenem with other antibiotic regimes for the treatment of patients with infections.

RESULTS

Eight RCTs were included in the meta-analysis, involving totally 1685 patients with lower respiratory tract infections (LRTIs), complicated urinary tract infections (cUTIs), and complicated intra-abdominal infections (cIAIs). There was no difference found between the patients with LRTIs, cUTIs, or cIAIs treated with biapenem and comparators, regarding treatment success and adverse events.

CONCLUSION

This meta-analysis provides evidence that biapenem can be used as effectively and safely as imipenem-cilstatin or meropenem, for the treatment of patients with LRTIs, cUTIs, and cIAIs. It may be a considerable option for the treatment of these infections.

Optimal dosing regimen of biapenem in Chinese patients with lower respiratory tract infections based on population pharmacokinetic/pharmacodynamic modelling and Monte Carlo simulation

In this study, a population pharmacokinetic (PPK) model of biapenem in Chinese patients with lower respiratory tract infections (LRTIs) was developed and optimal dosage regimens based on Monte Carlo simulation were proposed. A total of 297 plasma samples from 124 Chinese patients were assayed chromatographically in a prospective, single-centre, open-label study, and pharmacokinetic parameters were analysed using NONMEN. Creatinine clearance (CLCr) was found to be the most significant covariate affecting drug clearance. The final PPK model was: CL (L/h)=9.89+(CLCr-66.56)×0.049; Vc (L)=13; Q (L/h)=8.74; and Vp (L)=4.09. Monte Carlo simulation indicated that for a target of ≥40% T>MIC (duration that the plasma level exceeds the causative pathogen's MIC), the biapenem pharmacokinetic/pharmacodynamic (PK/PD) breakpoint was 4μg/mL for doses of 0.3g every 6h (3-h infusion) and 1.2g (24-h continuous infusion). For a target of ≥80% T>MIC, the PK/PD breakpoint was 4μg/mL for a dose of 1.2g (24-h continuous infusion). The probability of target attainment (PTA) could not achieve ≥90% at the usual biapenem dosage regimen (0.3g every 12h, 0.5-h infusion) when the MIC of the pathogenic bacteria was 4μg/mL, which most likely resulted in unsatisfactory clinical outcomes in Chinese patients with LRTIs. Higher doses and longer infusion time would be appropriate for empirical therapy. When the patient's symptoms indicated a strong suspicion of Pseudomonas aeruginosa or Acinetobacter baumannii infection, it may be more appropriate for combination therapy with other antibacterial agents.

Efficacy and safety of biapenem against lower respiratory tract infections in elderly Chinese patients and optimal dosing regimen based on pharmacokinetic/pharmacodynamic analysis

The present study evaluated the efficacy and safety of biapenem in elderly Chinese patients with lower respiratory tract infections (LRTIs) and proposed optimal dosage regimen on the basis of pharmacokinetic/pharmacodynamic (PK/PD) analysis. The clinical efficacy, bacterial eradication and comprehensive therapeutic effect rates of biapenem were 70.3 (78/111), 68.5 (37/54) and 61.1% (33/54), respectively. Drug-related adverse reactions were seen in 12.6% of patients (14/111). The total protein level, Acute Physiology and Chronic Health Evaluation (APACHE) II score, %fT>MIC, fAUC24/MIC and fCmax/MIC values of patients had significant impacts (P < 0.05) on clinical and bacteriological efficacy. However, logistic regression analysis showed that only %fT>MIC independently influenced comprehensive therapeutic effect (P < 0.01, odds ratio = 1.064). The cut-off value for predicting comprehensive therapeutic effect using %fT>MIC was 75.0%; the sensitivity and specificity were 87.9 and 85.7%, respectively. Monte Carlo simulations revealed that the usual dosage regimen (300 mg every 12 hours, 0.5 hour infusion) was considered to be insufficient to obtain satisfactory therapeutic outcomes against low susceptible pathogens for elderly Chinese patients with LRTIs (CLcr = 70 ml/min).

Development of novel antibacterial drugs to combat multiple resistant organisms

BACKGROUND

Infections due to multidrug-resistant (MDR) bacteria are increasing both in hospitals and in the community and are characterized by high mortality rates. New molecules are in development to face the need of active compounds toward resistant gram-positive and gram-negative pathogens. In particular, the Infectious Diseases Society of America (IDSA) has supported the initiative to develop ten new antibacterials within 2020. Principal targets are the so-called ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacteriaceae).

PURPOSE

To review the characteristics and the status of development of new antimicrobials including new cephalosporins, carbapenems, beta-lactamase inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines.

CONCLUSIONS

While numerous new compounds target resistant gram-positive pathogens and have been approved for clinical use, very few new molecules are active against MDR gram-negative pathogens, especially carbapenemase producers. New glycopeptides and oxazolidinones are highly efficient against methicillin-resistant S. aureus (MRSA), and new cephalosporins and carbapenems also display activity toward MDR gram-positive bacteria. Although new cephalosporins and carbapenems have acquired activity against MRSA, they offer few advantages against difficult-to-treat gram-negatives. Among agents that are potentially active against MDR gram-negatives are ceftozolane/tazobactam, new carbapenems, the combination of avibactam with ceftazidime, and plazomicin. Since a relevant number of promising antibiotics is currently in development, regulatory approvals over the next 5 years are crucial to face the growing threat of multidrug resistance.

In Vitro Analysis of Activities of 16 Antimicrobial Agents against Gram-Negative Bacteria from Six Teaching Hospitals in China

To evaluate the in vitro antimicrobial activities of biapenem, arbekacin, and cefminox against different gram-negative bacterial isolates in China, a total of 100 non-duplicated Escherichia coli, 100 Acinetobacter baumannii, 100 Pseudomonas aeruginosa, and 99 Klebsiella pneumoniae isolates were collected from 6 teaching hospitals in China in 2012. The minimal inhibitory concentrations (MICs) of biapenem, arbekacin, cefminox and 13 other antibiotics were determined by the broth microdilution method. The carbapenems (biapenem, meropenem, and imipenem) exhibited high antimicrobial activity against E. coli (98%) and K. pneumoniae (≥95%), followed by colistin and amikacin. The MIC50 and MIC90 of biapenem against E. coli were ≤0.06 mg/L and 0.25 mg/L, respectively. For K. pneumoniae, the MIC50 and MIC90 of biapenem were 0.25 mg/L and 1.0 mg/L, respectively. The MIC50 and MIC90 of cefminox against E. coli were 1.0 mg/L and 4.0 mg/L, respectively. The resistance rates of A. baumannii to most of the antibiotics were more than 50%, except for colistin. Amikacin was the most active antibiotic against P. aeruginosa (97%), followed by colistin (93%). The MIC50 and MIC90 of arbekacin against P. aeruginosa were 2.0 mg/L and 8.0 mg/L, respectively. In conclusion, carbapenems, colistin, amikacin, and arbekacin exhibited high antimicrobial activities against gram-negative bacteria, except A. baumannii.

An enzoinformatics study for prediction of efficacies of three novel penem antibiotics against New Delhi metallo-β-lactamase-1 bacterial enzyme

New Delhi metallo-beta-lactamase (NDM-1) is a beta-lactamase (class B carbapenemase) containing Zn(2+) and other divalent cations as cofactors which possesses the ability to inactivate all beta lactams (including carbapenems) except aztreonam by catalyzing the hydrolytic cleavage of the substrate amide bond. Carbapenemases are either serine enzymes or metallo-β-lactamases (MBLs) that utilize at least one zinc ion for hydrolysis. The present study describes the molecular interaction of carbapenems (Imipenem, Meropenem, Ertapenem, Doripenem, Panipenem, Biapenem, Razupenem, Faropenem, Tebipenem and Tomopenem) with NDM-1, β-lactamase enzyme. Docking between NDM-1 and each of these carbapenems (separately) was performed using 'Autodock4.2'.

An enzoinformatics study for prediction of efficacies of three novel penem antibiotics against New Delhi metallo-β-lactamase-1 bacterial enzyme

New Delhi metallo-beta-lactamase (NDM-1) is a beta-lactamase (class B carbapenemase) containing Zn2+ and other divalent cations as cofactors which possesses the ability to inactivate all beta lactams (including carbapenems) except aztreonam by catalyzing the hydrolytic cleavage of the substrate amide bond. Carbapenemases are either serine enzymes or metallo-β-lactamases (MBLs) that utilize at least one zinc ion for hydrolysis. The present study describes the molecular interaction of carbapenems (Imipenem, Meropenem, Ertapenem, Doripenem, Panipenem, Biapenem, Razupenem, Faropenem, Tebipenem and Tomopenem) with NDM-1, β-lactamase enzyme. Docking between NDM-1 and each of these carbapenems (separately) was performed using 'Autodock4.2'.

The efficacy, safety, and pharmacokinetics of biapenem administered thrice daily for the treatment of pneumonia in the elderly

Biapenem has been widely used to treat bacterial pneumonia; however, there is little information concerning its efficacy and safety in elderly patients. Based on pharmacokinetic-pharmacodynamic theory, administration of biapenem thrice rather than twice daily would be expected to be more effective because of longer time above the minimum inhibitory concentration. In this study, we aimed to evaluate the efficacy, safety, and pharmacokinetics of biapenem (300 mg) administered thrice daily in pneumonic patients aged 65 years or older. Biapenem was effective in 22 of 25 patients, as assessed by the improvement in clinical symptoms and/or the eradication of the causative organisms, and caused no serious adverse events. The pharmacokinetic profile was established based on simulations using a modeling program. Among 17 patients whose causative organisms were detected, time above the minimum inhibitory concentration was estimated to be 100% in 16 patients, all of whom showed clinical improvement. The results of this study confirmed the efficacy and safety of 300 mg of biapenem administered thrice daily for the treatment of pneumonia in elderly patients.

New antibiotics for bad bugs: where are we?

Bacterial resistance to antibiotics is growing up day by day in both community and hospital setting, with a significant impact on the mortality and morbidity rates and the financial burden that is associated. In the last two decades multi drug resistant microorganisms (both hospital- and community-acquired) challenged the scientific groups into developing new antimicrobial compounds that can provide safety in use according to the new regulation, good efficacy patterns, and low resistance profile. In this review we made an evaluation of present data regarding the new classes and the new molecules from already existing classes of antibiotics and the ongoing trends in antimicrobial development. Infectious Diseases Society of America (IDSA) supported a proGram, called “the ′10 × ´20′ initiative”, to develop ten new systemic antibacterial drugs within 2020. The microorganisms mainly involved in the resistance process, so called the ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and enterobacteriaceae) were the main targets. In the era of antimicrobial resistance the new antimicrobial agents like fifth generation cephalosporins, carbapenems, monobactams, β-lactamases inhibitors, aminoglycosides, quinolones, oxazolidones, glycopeptides, and tetracyclines active against Gram-positive pathogens, like vancomycin-resistant S. aureus (VRSA) and MRSA, penicillin-resistant streptococci, and vancomycin resistant Enterococcus (VRE) but also against highly resistant Gram-negative organisms are more than welcome. Of these compounds some are already approved by official agencies, some are still in study, but the need of new antibiotics still does not cover the increasing prevalence of antibiotic-resistant bacterial infections. Therefore the management of antimicrobial resistance should also include fostering coordinated actions by all stakeholders, creating policy guidance, support for surveillance and technical assistance.

In vitro activity of Biapenem plus RPX7009, a carbapenem combined with a serine β-lactamase inhibitor, against anaerobic bacteria

Biapenem is a carbapenem being developed in combination with RPX7009, a new inhibitor of serine β-lactamases. Biapenem was tested alone and in combination with fixed concentrations of RPX7009 by agar dilution against 377 recent isolates of anaerobes. A separate panel of 27 isolates of Bacteroides spp. with decreased susceptibility or resistance to imipenem was also tested. Comparator drugs included meropenem, piperacillin-tazobactam, ampicillin-sulbactam, cefoxitin, ceftazidime, metronidazole, clindamycin, and tigecycline plus imipenem, doripenem, and ertapenem for the 27 selected strains. For recent consecutive strains of Bacteroides species, the MIC(90) for biapenem-RPX7009 was 1 μg/ml, with a MIC(90) of 4 μg/ml for meropenem. Other Bacteroides fragilis group species showed a MIC90 of 0.5 μg/ml for both agents. The MIC(90)s for biapenem-RPX7009 were 0.25 μg/ml for Prevotella spp., 0.125 μg/ml for Fusobacterium nucleatum and Fusobacterium necrophorum, 2 μg/ml for Fusobacterium mortiferum, 0.5 μg/ml for Fusobacterium varium, ≤ 0.5 μg/ml for Gram-positive cocci and rods, and 0.03 to 8 μg/ml for clostridia. Against 5 B. fragilis strains harboring a known metallo-beta-lactamase, biapenem-RPX7009 MICs were comparable to those of other carbapenems (≥ 32 μg/ml). Against Bacteroides strains with an imipenem MIC of 2 μg/ml, biapenem-RPX7009 had MICs of 0.5 to 2 μg/ml, with MICs of 0.5 to 32 μg/ml for meropenem, doripenem, and ertapenem. For strains with an imipenem MIC of 4 μg/ml, the MICs for biapenem-RPX7009 were 4 to 16 μg/ml, with MICs of 8 to >32 μg/ml for meropenem, doripenem, and ertapenem. The inhibitor RPX7009 had no antimicrobial activity when tested alone, and it showed little or no potentiation of biapenem versus anaerobes. Biapenem-RPX7009 showed activity comparable to that of imipenem and was superior to meropenem, doripenem, and ertapenem against imipenem-nonsusceptible Bacteroides spp.

Pharmacologically prospective antibiotic agents and their sources: a marine microbial perspective

Marine microbes have been a storehouse of bioactive metabolites with tremendous potential as drug candidates. Marine microorganism derived secondary metabolites (chemical compounds/peptides) are considered to be a burning area of research since recent past. Many of such compounds have been proven to be anti-bacterial, anti-fungal, anti-algal, anti-HIV, anti-helminthic, anti-protozoan, anti-tumor and anti-allergic agents. Marine bacteria and fungi have been reported to be the producers of such compounds owing to their defense mechanisms and metabolic by products. Although the number of natural products isolated from these classes of marine microbial flora is large, a limited number of such compounds reach the clinical trial and even less number of them get approved as a drug. Here we discuss the recent studies on the isolation, characterization and the pharmacological significances of anti-bacterial, anti-fungal and anti-infective agents of marine microbial origin. Further, the clinical status of such compounds has also been discussed in comparison with those derived from their terrestrial counterparts.

Carbapenems: past, present, and future

In this review, we summarize the current "state of the art" of carbapenem antibiotics and their role in our antimicrobial armamentarium. Among the β-lactams currently available, carbapenems are unique because they are relatively resistant to hydrolysis by most β-lactamases, in some cases act as "slow substrates" or inhibitors of β-lactamases, and still target penicillin binding proteins. This "value-added feature" of inhibiting β-lactamases serves as a major rationale for expansion of this class of β-lactams. We describe the initial discovery and development of the carbapenem family of β-lactams. Of the early carbapenems evaluated, thienamycin demonstrated the greatest antimicrobial activity and became the parent compound for all subsequent carbapenems. To date, more than 80 compounds with mostly improved antimicrobial properties, compared to those of thienamycin, are described in the literature. We also highlight important features of the carbapenems that are presently in clinical use: imipenem-cilastatin, meropenem, ertapenem, doripenem, panipenem-betamipron, and biapenem. In closing, we emphasize some major challenges and urge the medicinal chemist to continue development of these versatile and potent compounds, as they have served us well for more than 3 decades.

Epileptogenic potential of carbapenem agents: mechanism of action, seizure rates, and clinical considerations

Antimicrobials are the most frequently implicated class of drugs in drug-induced seizure, with β-lactams being the class of antimicrobials most often implicated. The seizure-inducing potential of the carbapenem subclass may be directly related to their β-lactam ring structure. Data on individual carbapenems and seizure activity are scarce. To evaluate the available evidence on the association between carbapenem agents and seizure activity, we conducted a literature search of the MEDLINE (1966-May 2010), EMBASE (1974-May 2010), and International Pharmaceutical Abstracts (1970-May 2010) databases. Reference citations from the retrieved articles were also reviewed. Mechanistically, seizure propensity of the β-lactams is related to their binding to γ-aminobutyric acid (GABA) receptors. There are numerous reports of seizure activity associated with imipenem-cilastatin, with seizure rates ranging from 3-33%. For meropenem, doripenem, and ertapenem, the seizure rate for each agent is reported as less than 1%. However, as their use increases and expands into new patient populations, the rate of seizures with these agents may increase. High-dose therapy, especially in patients with renal dysfunction, preexisting central nervous system abnormalities, or a seizure history increases the likelihood of seizure activity. Although specific studies have not been conducted, data indicate that carbapenem-associated seizure is best managed with benzodiazepines, followed by other agents that enhance GABA transmission. Due to the drug interaction between carbapenems and valproic acid, resulting in clinically significant declines in valproic acid serum concentrations, the combination should be avoided whenever possible. Clinicians should be vigilant regarding the possibility of carbapenem-induced seizures when selecting and dosing antimicrobial therapy.

Clinical efficacy of carbapenems on hospital-acquired pneumonia in accordance with the Japanese Respiratory Society Guidelines for management of HAP

Hospital-acquired pneumonia (HAP) is the second most common cause of hospital-acquired infection and is the leading cause of death. In 2002, the Japanese Respiratory Society (JRS) published guidelines for the diagnosis and treatment of HAP (JRS GL 2002). In these guidelines, treatment with carbapenems is recommended for all disease types of HAP, excluding cases of mild or moderate pneumonia with no risk factors, and cases with early-onset ventilation-acquired pneumonia. To evaluate the efficacy of carbapenems on HAP in accordance with JRS GL 2002, we conducted a prospective study of HAP patients treated with carbapenems based on JRS GL 2002. The results of this study were also analyzed based on the revised guidelines published in June 2008 (JRS GL 2008), and the validity of the new guidelines was examined. Of the 33 subjects, 19 were judged as responders to the treatment, corresponding to a response rate of 57.6%. There were 3 deaths, corresponding to a mortality rate of 9.1%. The efficacy of carbapenems for the treatment of HAP based on JRS GL 2002 was confirmed. The severity rating system in JRS GL 2002 has a tendency to overestimate the severity of the cases and may lead to overtreatment in some cases. On the other hand, the severity rating system by JRS GL 2008 seemed to be more accurate and closely correlated with the efficacy of the treatment. It is suggested that JRS GL 2008 is more useful in clinical practice for accurately judging the severity of the disease and initiating appropriate subsequent antibiotic therapy.

Comparison of the pharmacodynamics of biapenem in bronchial epithelial lining fluid in healthy volunteers given half-hour and three-hour intravenous infusions

The time above the MIC (T>MIC) is the pharmacokinetic/pharmacodynamic (PK/PD) parameter that correlates with the therapeutic efficacy of beta-lactam antibiotics. A prolonged infusion can provide plasma drug concentrations that remain above the MIC for a long period. The objective of this study was to compare the PK/PD parameters in bronchial epithelial lining fluid (ELF) of biapenem given as 0.5-h and 3-h infusions by using bronchoscopic microsampling (BMS). Six healthy adult volunteers received 0.5-h and 3-h infusions of 0.3 g of biapenem with a washout interval. BMS was performed repeatedly from 0.5 to 24 h after biapenem administration in order to determine the pharmacokinetics in bronchial ELF. The subjects received intravenous biapenem with the same regimens again and then underwent bronchoalveolar lavage (BAL) at the end of infusion in order to determine the concentration of the drug in alveolar ELF. The percentages (means +/- standard deviations) of T>MIC in bronchial ELF at MICs from 0.25 to 4 microg/ml ranged from zero to 34.6% +/- 5.2% after the 0.5-h infusion and from 5.1% +/- 5.6% to 52.2% +/- 17.0% after the 3-h infusion. The percentage of T>MIC in bronchial ELF after the 3-h infusion tended to be higher than that after the 0.5-h infusion. The concentrations of the drug in alveolar ELF after 0.5-h and 3-h infusions were 3.5 +/- 1.2 microg/ml and 1.3 +/- 0.3 microg/ml, respectively. The present results support the use of prolonged infusions of beta-lactam antibiotics and may provide critical information for successful treatment of lower respiratory tract infections based on PK/PD parameters in bronchial ELF.

The stability of biapenem and structural identification of impurities in aqueous solution

The stability of biapenem in aqueous solution was investigated. Forced degradation of biapenem was carried out under different concentrations, pH values and temperatures. The degradation products were determined by reverse-phase HPLC and identified by LC-MS/MS. One dimeric impurity was obtained by reverse-phase preparative HPLC and characterized by LC-MS/MS and NMR. A possible degradation mechanism has been presented.

Crystal structures of biapenem and tebipenem complexed with penicillin-binding proteins 2X and 1A from Streptococcus pneumoniae

Biapenem is a parenteral carbapenem antibiotic that exhibits wide-ranging antibacterial activity, remarkable chemical stability, and extensive stability against human renal dehydropeptidase-I. Tebipenem is the active form of tebipenem pivoxil, a novel oral carbapenem antibiotic that has a high level of bioavailability in humans, in addition to the above-mentioned features. beta-lactam antibiotics, including carbapenems, target penicillin-binding proteins (PBPs), which are membrane-associated enzymes that play essential roles in peptidoglycan biosynthesis. To envisage the binding of carbapenems to PBPs, we determined the crystal structures of the trypsin-digested forms of both PBP 2X and PBP 1A from Streptococcus pneumoniae strain R6, each complexed with biapenem or tebipenem. The structures of the complexes revealed that the carbapenem C-2 side chains form hydrophobic interactions with Trp374 and Thr526 of PBP 2X and with Trp411 and Thr543 of PBP 1A. The Trp and Thr residues are conserved in PBP 2B. These results suggest that interactions between the C-2 side chains of carbapenems and the conserved Trp and Thr residues in PBPs play important roles in the binding of carbapenems to PBPs.

Pharmacokinetic and pharmacodynamic properties of biapenem, a carbapenem antibiotic, in rat experimental model of severe acute pancreatitis

OBJECTIVES

It is known that prophylaxis with imipenem reduces the risk of infection accompanying severe acute pancreatitis. In this study,we modified a rat experimental model of severe acute pancreatitis for antibiotic evaluation, and the effect of biapenem was compared with that of imipenem to determine the usefulness of biapenem.

METHODS

Severe acute pancreatitis was induced by 5% sodium taurocholate. Antibiotics were subcutaneously administered at 3 and 6 hours and evaluated at 12 hours after the pancreatitis induction. For pharmacokinetic evaluation, antibiotics were subcutaneously administered at 3 hours after the pancreatitis induction.

RESULTS

From 3 hours after the induction, bacteria were detected from the pancreas. The total bacterial count increased in a time-dependent manner for 12 hours. Biapenem administration reduced the total bacterial count in the pancreas, as observed in imipenem administration. The plasma concentration of biapenem was almost equivalent to that of imipenem; however, the pancreatic penetration of biapenem was approximately twice that of imipenem in this model.

CONCLUSIONS

Biapenem was suggested to be effective in prophylactic treatment of infectious complications as much as imipenem because of its superior penetration to the pancreas in severe acute pancreatitis.