Pharmacokinetics of cephalosporins in the neonate: a review

An Overview of Antibiotic Therapy for Early- and Late-Onset Neonatal Sepsis: Current Strategies and Future Prospects

Neonatal sepsis is a clinical syndrome mainly associated with a bacterial infection leading to severe clinical manifestations that could be associated with fatal sequalae. According to the time of onset, neonatal sepsis is categorized as early- (EOS) or late-onset sepsis (LOS). Despite blood culture being the gold standard for diagnosis, it has several limitations, and early diagnosis is not immediate. Consequently, most infants who start empirical antimicrobial therapy do not have an underlying infection. Despite stewardship programs partially reduced this negative trend, in neonatology, antibiotic overuse still persists, and it is associated with several relevant problems, the first of which is the increase in antimicrobial resistance (AMR). Starting with these considerations, we performed a narrative review to summarize the main findings and the future prospects regarding antibiotics use to treat neonatal sepsis. Because of the impact on morbidity and mortality that EOS and LOS entail, it is essential to start an effective and prompt treatment as soon as possible. The use of targeted antibiotics is peremptory as soon as the pathogen in the culture is detected. Although prompt therapy is essential, it should be better assessed whether, when and how to treat neonates with antibiotics, even those at higher risk. Considering that we are certainly in the worrying era defined as the "post-antibiotic era", it is still essential and urgent to define novel strategies for the development of antibacterial compounds with new targets or mechanisms of action. A future strategy could also be to perform well-designed studies to develop innovative algorithms for improving the etiological diagnosis of infection, allowing for more personalized use of the antibiotics to treat EOS and LOS.

Optimal dose of cefotaxime in neonates with early-onset sepsis: A developmental pharmacokinetic model-based evaluation

Objective: The perspective of real-world study is especially relevant to newborns, enabling dosage regimen optimization and regulatory approval of medications for use in newborns. The aim of the present study was to conduct a pharmacokinetic analysis of cefotaxime and evaluate the dosage used in newborns with early-onset sepsis (EOS) using real-world data in order to support the rational use in the clinical practice.

Methods: This prospective, open-label study was performed in newborns with EOS. A developmental pharmacokinetic-pharmacodynamic model of cefotaxime in EOS patients was established based on an opportunistic sampling method. Then, clinical evaluation of cefotaxime was conducted in newborns with EOS using real-world data.

Results: A one-compartment model with first-order elimination was developed, using 101 cefotaxime concentrations derived from 51 neonates (30.1–41.3°C weeks postmenstrual age), combining current weight and postnatal age. The pharmacokinetic-pharmacodynamic target was defined as the free cefotaxime concentration above MIC during 70% of the dosing interval (70% fT > MIC), and 100% of neonates receiving the dose of 50 mg/kg, BID attained the target evaluated using the model. Additionally, only two newborns had adverse reactions possibly related to cefotaxime treatment, including diarrhea and feeding intolerance.

Conclusion: This prospective real-world study demonstrated that cefotaxime (50 mg/kg, BID) had a favorable efficacy and an accepted safety profile for neonates with EOS.

Use of Antibiotics in Preterm Newborns

Due to complex maturational and physiological changes that characterize neonates and affect their response to pharmacological treatments, neonatal pharmacology is different from children and adults and deserves particular attention. Although preterms are usually considered part of the neonatal population, they have physiological and pharmacological hallmarks different from full-terms and, therefore, need specific considerations. Antibiotics are widely used among preterms. In fact, during their stay in neonatal intensive care units (NICUs), invasive procedures, including central catheters for parental nutrition and ventilators for respiratory support, are often sources of microbes and require antimicrobial treatments. Unfortunately, the majority of drugs administered to neonates are off-label due to the lack of clinical studies conducted on this special population. In fact, physiological and ethical concerns represent a huge limit in performing pharmacokinetic (PK) studies on these subjects, since they limit the number and volume of blood sampling. Therapeutic drug monitoring (TDM) is a useful tool that allows dose adjustments aiming to fit plasma concentrations within the therapeutic range and to reach specific drug target attainment. In this review of the last ten years’ literature, we performed Pubmed research aiming to summarize the PK aspects for the most used antibiotics in preterms.

Treatment options for neonatal infections in the post-cefotaxime era

INTRODUCTION

: Cefotaxime has been used for the management of neonatal infections since the 1990s for suspected meningitis and to mitigate gentamicin-associated renal injury. Its shortage in 2015 and subsequent removal from the U.S. pharmaceutical market forced providers to consider alternatives. Ceftriaxone, a cephalosporin with an identical antibacterial spectrum of activity to cefotaxime, is contraindicated in neonates due to its risk of biliary pseudolithiasis. Ceftazidime was recommended as an alternative by the American Academy of Pediatrics but is inequivalent.

AREAS COVERED

: This article addresses indications for cephalosporin use and considerations when selecting an alternative to cefotaxime. Differences among cefotaxime, ceftriaxone, ceftazidime, and cefepime are discussed and compared to the standard-of-care presumptive regimen, ampicillin and gentamicin. The authors consider the data behind the neonatal contraindication to ceftriaxone and provide recommendations for their application to practice.

EXPERT OPINION

: The data against ceftriaxone use in neonates remain poor, particularly in the context of the cefotaxime shortage and lack of an equivalent alternative. Ceftriaxone could be considered in low-risk neonates without hyperbilirubinemia or exposure to calcium-containing fluids on a case-by-case basis. Ceftazidime monotherapy for presumptive management of neonatal infections is inappropriate; cefepime should be more frequently utilized in neonates who are poor candidates for ceftriaxone.

Synthesis, Spectroscopic Studies for Five New Mg (II), Fe (III), Cu (II), Zn (II) and Se (IV) Ceftriaxone Antibiotic Drug Complexes and Their Possible Hepatoprotective and Antioxidant Capacities

Magnesium, copper, zinc, iron and selenium complexes of ceftriaxone were prepared in a 1:1 ligand to metal ratio to investigate the ligational character of the antibiotic ceftriaxone drug (CFX). The complexes were found to have coordinated and hydrated water molecules, except for the Se (IV) complex, which had only hydrated water molecules. The modes of chelation were explained depending on IR, 1HNMR and UV-Vis spectroscopies. The electronic absorption spectra and the magnetic moment values indicated that Mg (II), Cu (II), Zn (II), Fe (III) and Se (VI) complexes form a six-coordinate shape with a distorted octahedral geometry. Ceftriaxone has four donation sites through nitrogen from NH2 amino, oxygen from triazine, β-lactam carbonyl and carboxylate with the molecular formulas [Mg(CFX)(H2O)2]·4H2O, [Cu(CFX)(H2O)2]·3H2O, [Fe(CFX)(H2O)(Cl)]·5H2O, [Zn(CFX)(H2O)2]·6H2O and [Se(CFX)(Cl)2]·4H2O and acts as a tetradentate ligand towards the five metal ions. The morphological surface and particle size of ceftriaxone metal complexes were determined using SEM, TEM and X-ray diffraction. The thermal behaviors of the complexes were studied by the TGA(DTG) technique. This study investigated the effect of CFX and CFX metal complexes on oxidative stress and severe tissue injury in the hepatic tissues of male rats. Fifty-six male rats were tested: the first group received normal saline (1 mg/kg), the second group received CFX orally at a dose of 180 mg/kg, and the other treated groups received other CFX metal complexes at the same dose as the CFX-treated group. For antibacterial activity, CFX/Zn complex was highly effective against Streptococcus pneumoniae, while CFX/Se was highly effective against Staphylococcus aureus and Escherichia coli. In conclusion, successive exposure to CFX elevated hepatic reactive oxygen species (ROS) levels and lipid peroxidation final marker (MDA) and decreased antioxidant enzyme levels. CFX metal complex administration prevented liver injury, mainly suppressing excessive ROS generation and enhancing antioxidant defense enzymes and in male rats.

Pharmacokinetic and pharmacodynamic considerations of cephalosporin use in children

Introduction: Cephalosporins are a major class of antibiotics, frequently used in children because of their remarkable antibacterial activity and excellent safety profile. Time above the minimal inhibitory concentration of the non-protein-bound fraction (fT>MIC) is the pharmacokinetic/pharmacodynamic parameter that correlates with the therapeutic efficacy. In the pediatric population, the inter-individual variability in cephalosporin pharmacokinetics is large because of maturational changes. However, the prescription of cephalosporins promotes emergence of Enterobacteriaceae producing broad-spectrum ß-lactamases.Areas covered: Here we describe in vitro activities and the main pharmacokinetic characteristics of cephalosporins in children. On the basis of these characteristics, we propose an estimation of the fT>MIC for each molecule as a tool to help optimize the use of cephalosporins. We also provide an inventory of the clinical use of cephalosporins and present prospects for the development of new molecules or associations to address the emergence of resistant strains.Expert opinion: Cephalosporins represent a heterogeneous group of antibiotics with various pharmacokinetics and in vitro antimicrobial activity that the clinician needs to master to optimize their use. However, their broad use plays a role in the emergence of broad-spectrum ß-lactamase-producing strains and must thus be restricted to probabilistic broad-spectrum therapy and situations without therapeutic alternatives.

Duration of empirical therapy in neonatal bacterial meningitis with third generation cephalosporin: a multicenter retrospective study

INTRODUCTION

The duration of treatment is not well established, especially in the negative cerebrospinal fluid (CSF) culture. The aim of this study is to explore the influence of duration of treatment in neonatal bacterial meningitis.

MATERIAL AND METHODS

This is a retrospective analysis of 200 CSF specimens. Two hundred full-term neonates with bacterial meningitis admitted to the clinical status were evaluated using the Glasgow Outcome Scale (GOS) on the day of discharge.

RESULTS

Neonates were identified as having bacterial meningitis based on the results of CSF culture tests of all suspected cases. According to the GOS, neonates were divided into two outcome groups: 77.5% good (GOS = 5) (shorter than 3 weeks' administration) and 22.5% unfavorable (GOS = 1-4) (longer than 3 weeks' administration). The duration of antibiotic treatment ranged from 4 to 43 days, and the mean therapy time was 19.74 ±7.32 days. Duration longer than 3 weeks for neonatal bacterial meningitis with negative CSF culture had no impact on prognosis. The unfavorable outcome group had more prenatal infections and premature rupture of membranes cases than the good outcome group. High CSF protein and CSF glucose and CSF cell count increase were associated with unfavorable outcome in 167 non-prenatal infection infants. High CSF cell count increase was associated with unfavorable outcome in 33 prenatal infection infants. In term infants, the positive rate of blood cultures was 24.5%.

CONCLUSIONS

Third generation cephalosporin therapy does not have a different prognosis for negative CSF culture of neonatal bacterial meningitis in term infants in this study.

Drugs for the Prevention and Treatment of Sepsis in the Newborn

Antimicrobial medications are the most commonly used medications in the neonatal intensive care unit. Antibiotics are used for infection prophylaxis, empiric treatment, and definitive treatment of confirmed infection. The choice of medication should be informed by the epidemiology and microbiology of infection in specific clinical scenarios and by the clinical condition of the infant. Understanding evolving pathogen susceptibility to antimicrobials and key pharmacotherapy determinants in neonates can inform optimal antibiotic use.

Ceftriaxone Absorption Enhancement for Noninvasive Administration as an Alternative to Injectable Solutions

Neonatal sepsis is a major cause of infant mortality in developing countries because of delayed injectable treatment, making it urgent to develop noninjectable formulations that can reduce treatment delays in resource-limited settings. Ceftriaxone, available only for injection, needs absorption enhancers to achieve adequate bioavailability via nonparenteral administration. This article presents all available data on the nonparenteral absorption of ceftriaxone in humans and animals, including unpublished work carried out by F. Hoffmann-La Roche (Roche) in the 1980s and new data from preclinical studies with rabbits, and discusses the importance of these data for the development of noninjectable formulations for noninvasive treatment. The combined results indicate that the rectal absorption of ceftriaxone is feasible and likely to lead to a bioavailable formulation that can reduce treatment delays in neonatal sepsis. A bile salt, chenodeoxycholate sodium salt (Na-CDC), used as an absorption enhancer at a 125-mg dose, together with a 500-mg dose of ceftriaxone provided 24% rectal absorption of ceftriaxone and a maximal plasma concentration of 21 µg/ml with good tolerance in human subjects. The rabbit model developed can also be used to screen for the bioavailability of other formulations before assessment in humans.

The consequences of prolonged duration of antibiotics in premature infants with suspected sepsis in a large tertiary referral hospital: a retrospective cohort study

Objective

To assess whether there is any association between prolonged duration of the first course of empirical antibiotic treatment for suspected neonatal sepsis and other factors including comorbidities, interventions, and adverse outcomes.

Background

Neonatal sepsis is one of the main reasons of mortality among premature infants in Neonatal Intensive Care Unit (NICU). Therefore, commencing antibiotics treatment on admission plays a crucial role in reducing the complications of neonatal sepsis, however the arbitrary use of antibiotics holds many serious complications. In our study we investigated the complications of prolonged use of antibiotics in treating suspected early onset of sepsis.

Study design

This is a retrospective cohort study of infants of gestational age 32 weeks or less and with birth weight of 1500 g or less along with suspected neonatal sepsis admitted to our neonatal intensive care unit from July 2015 to June 2017. The study outcome measures were the association between the antibiotic treatment duration and maternal factors, gender, adverse outcomes, developmental factors, comorbid conditions, early-onset sepsis, and late-onset sepsis.

Results

Of 295 premature infants, late-onset sepsis was associated with the duration of early empiric antibiotic use (n = 54/295), where 50 (92.6%) infants with LOS received the antibiotic treatment for more than 5 days (P < .001). Approximately 91.2% of those receiving the prolonged treatment had a positive blood culture result. Necrotizing enterocolitis was more prevalent in those with long duration of antibiotic treatment (95.1%). Among patients with the comorbid conditions patent ductus arteriosus (n = 123/295), intraventricular hemorrhage (n = 73/295), and periventricular leukomalacia (n = 25/295), 100 (81.3%), 60 (82.2%), and 21 (84%) of them, respectively, received prolonged treatment.

Conclusion

Prolonged administration of empiric antibiotics to infants with very low birth weight along with sterile cultures is associated with the adverse outcomes late-onset sepsis and necrotizing enterocolitis. However, no association with other adverse outcomes, namely, candidiasis or maternal factors, was found.

Antimicrobial drug-related problems in a neonatal intensive care unit

Objective

The goal was to determine the main drug-related problems in neonates who were using antimicrobials.

Method

This was an observational, prospective and longitudinal study. Drug-related problems were classified according to version 6.2 of the Pharmaceutical Care Network Europe Foundation classification. A descriptive analysis was performed, in which the clinical and therapeutic variables were presented as absolute and relative frequencies or as the mean and standard deviation, as appropriate.

Results

In total, 152 neonates with a predominance of males (58.5%), gestational age of 32.7 ± 4.2 weeks and weight of 1,903.1 ± 846.9g were included. The main diagnostic hypothesis of infection was early sepsis (66.5%), and 71.7% of the neonates had some risk factor for infection. Among the neonates, 33.6% had at least one drug-related problem. Of these, 84.8% were related to treatment effectiveness and 15.2% to adverse reactions. The main cause of drug-related problems was the selected dose, particularly for aminoglycosides and cephalosporins.

Conclusion

The use of antimicrobials in the neonatal intensive care is mainly associated with problems related to medication effectiveness, predominantly the prescription of subdoses of antimicrobials, especially aminoglycosides.

Ceftriaxone-Associated Biliary and Cardiopulmonary Adverse Events in Neonates: A Systematic Review of the Literature

BACKGROUND

Ceftriaxone is a third-generation cephalosporin with broad-spectrum activity against both Gram-positive and Gram-negative bacteria. Despite its effectiveness, its use for the treatment of infections in neonatal patients has been limited because of concern about its potential toxicity.

OBJECTIVE

Our aim was to review the literature for an association between ceftriaxone and cardiopulmonary events, hyperbilirubinemia, and pseudolithiasis among neonates.

METHODS

We searched PubMed and EMBASE and included studies that evaluated ceftriaxone safety in neonates. Study bias was evaluated in the following domains: exposure measurement, outcome measurement, attrition, generalizability, confounding, statistical analysis, and reporting.

RESULTS

We included nine studies regarding ceftriaxone side effects, primarily spontaneous reports, published case reports, and small case series. Reports of bilirubin displacement attributed to ceftriaxone included increases in serum bilirubin necessitating antibiotic change in a subset of infants after administration of ceftriaxone. One study described self-resolving biliary sludge after ceftriaxone administration in six of 80 infants. Cardiopulmonary adverse events included a report of eight cardiopulmonary events related to concomitant ceftriaxone-calcium infusion, including seven infant deaths. Additional cardiopulmonary events reported included perinatal asphyxia, pulmonary hypertension, and thrombocytosis. However, the available literature had small sample sizes, poor external validity, and inconsistent outcome ascertainment methods, which made it impossible to estimate the magnitude of risk.

DISCUSSION

Concomitant administration of intravenous ceftriaxone and calcium-containing solutions should be avoided in neonates. However, further controlled studies are needed to assess whether bilirubin displacement associated with the use of ceftriaxone is clinically relevant, particularly in healthy term and near-term neonates with mild hyperbilirubinemia.

A Population and Developmental Pharmacokinetic Analysis To Evaluate and Optimize Cefotaxime Dosing Regimen in Neonates and Young Infants

Cefotaxime is one of the most frequently prescribed antibiotics for the treatment of Gram-negative bacterial sepsis in neonates. However, the dosing regimens routinely used in clinical practice vary considerably. The objective of the present study was to conduct a population pharmacokinetic study of cefotaxime in neonates and young infants in order to evaluate and optimize the dosing regimen. An opportunistic sampling strategy combined with population pharmacokinetic analysis using NONMEM software was performed. Cefotaxime concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry. Developmental pharmacokinetics-pharmacodynamics, the microbiological pathogens, and safety aspects were taken into account to optimize the dose. The pharmacokinetic data from 100 neonates (gestational age [GA] range, 23 to 42 weeks) were modeled with an allometric two-compartment model with first-order elimination. The median values for clearance and the volume of distribution at steady state were 0.12 liter/h/kg of body weight and 0.64 liter/kg, respectively. The covariate analysis showed that current weight, GA, and postnatal age (PNA) had significant impacts on cefotaxime pharmacokinetics. Monte Carlo simulations demonstrated that the current dose recommendations underdosed older newborns. A model-based dosing regimen of 50 mg/kg twice a day to four times a day, according to GA and PNA, was established. The associated risk of overdose for the proposed dosing regimen was 0.01%. We determined the population pharmacokinetics of cefotaxime and established a model-based dosing regimen to optimize treatment for neonates and young infants.

Cefepime and Ceftazidime Safety in Hospitalized Infants

BACKGROUND

Cefepime and ceftazidime are cephalosporins used for the treatment of serious Gram-negative infections. These cephalosporins are used off-label in the setting of minimal safety data for young infants.

METHODS

We identified all infants discharged from 348 neonatal intensive care units managed by the Pediatrix Medical Group between 1997 and 2012 who were exposed to either cefepime or ceftazidime in the first 120 days of life. We reported clinical and laboratory adverse events occurring in infants exposed to cefepime or ceftazidime and used multivariable logistic regression to compare the odds of seizures and death between the 2 groups.

RESULTS

A total of 1761 infants received 13,293 days of ceftazidime, and 594 infants received 4628 days of cefepime. Laboratory adverse events occurred more frequently on days of therapy with ceftazidime than with cefepime (373 vs. 341 per 1000 infant days, P < 0.001). Seizure was the most commonly observed clinical adverse event, occurring in 3% of ceftazidime-treated infants and 4% of cefepime-treated infants (P = 0.52). Mortality was similar between the ceftazidime and cefepime groups (5% vs. 3%, P = 0.07). There was no difference in the adjusted odds of seizure [odds ratio (OR) = 0.96 (95% confidence interval: 0.89-1.03)] or the combined outcome of mortality or seizures [OR = 1.00 (0.96-1.04)] in infants exposed to ceftazidime versus those exposed to cefepime.

CONCLUSIONS

In this cohort of infants, cefepime was associated with fewer laboratory adverse events than ceftazidime, although this may have been due to a significant difference in clinical exposures and severity of illness between the 2 groups. There was no difference in seizure risk or mortality between the 2 drugs.

Adverse reaction to ceftriaxone in a 28-day-old infant undergoing urgent craniotomy due to epidural hematoma: review of neonatal biliary pseudolithiasis

The debate as to whether to administer ceftriaxone to neonates is likely to continue. Ceftriaxone has numerous advantages for critically ill pediatric patients. However, it is also known to contribute substantially to the development of biliary pseudolithiasis. Although pediatric patients rarely develop gallbladder disorders, this complication may lead to adverse events in high-risk patients with predisposing factors, particularly in neonates and infants treated with ceftriaxone. In this paper we present an interesting case report of a 28-day-old neonate with spontaneous severe epidural hematoma who developed biliary pseudolithiasis related to the use of ceftriaxone. We also discuss the efficacy of ceftriaxone in neonates and infants. Neonatologists and pediatric intensivists should be aware of the higher risk of co-existence of hyperbilirubinemia and gallbladder disorders while using ceftriaxone in pediatric settings.

High variability in the dosing of commonly used antibiotics revealed by a Europe-wide point prevalence study: implications for research and dissemination

BACKGROUND

Antibiotic dosing in neonates varies between countries and centres, suggesting suboptimal exposures for some neonates. We aimed to describe variations and factors influencing the variability in the dosing of frequently used antibiotics in European NICUs to help define strategies for improvement.

METHODS

A sub-analysis of the European Study of Neonatal Exposure to Excipients point prevalence study was undertaken. Demographic data of neonates receiving any antibiotic on the study day within one of three two-week periods from January to June 2012, the dose, dosing interval and route of administration of each prescription were recorded. The British National Formulary for Children (BNFC) and Neofax were used as reference sources. Risk factors for deviations exceeding ±25% of the relevant BNFC dosage recommendation were identified by multivariate logistic regression analysis.

RESULTS

In 89 NICUs from 21 countries, 586 antibiotic prescriptions for 342 infants were reported. The twelve most frequently used antibiotics - gentamicin, penicillin G, ampicillin, vancomycin, amikacin, cefotaxime, ceftazidime, meropenem, amoxicillin, metronidazole, teicoplanin and flucloxacillin - covered 92% of systemic prescriptions. Glycopeptide class, GA <32 weeks, 5(th) minute Apgar score <5 and geographical region were associated with deviation from the BNFC dosage recommendation. While the doses of penicillins exceeded recommendations, antibiotics with safety concerns followed (gentamicin) or were dosed below (vancomycin) recommendations.

CONCLUSIONS

The current lack of compliance with existing dosing recommendations for neonates needs to be overcome through the conduct of well-designed clinical trials with a limited number of antibiotics to define pharmacokinetics/pharmacodynamics, efficacy and safety in this population and by efficient dissemination of the results.

The interplay between drugs and the kidney in premature neonates

The kidney plays a central role in the clearance of drugs. However, renal drug handling entails more than glomerular filtration and includes tubular excretion and reabsorption, and intracellular metabolization by cellular enzyme systems, such as the Cytochrome P450 isoenzymes. All these processes show maturation from birth onwards, which is one of the reasons why drug dosing in children is not simply similar to dosing in small adults. As kidney development normally finishes around the 36th week of gestation, being born prematurely will result in even more immature renal drug handling. Environmental effects, such as extra-uterine growth restriction, sepsis, asphyxia, or drug treatments like caffeine, aminoglycosides, or non-steroidal anti-inflammatory drugs, may further hamper drug handling in the kidney. Dosing in preterm neonates is therefore dependent on many factors that need to be taken into account. Drug treatment may significantly hamper postnatal kidney development in preterm neonates, just like renal immaturity has an impact on drug handling. The restricted kidney development results in a lower number of nephrons that may have several long-term sequelae, such as hypertension, albuminuria, and renal failure. This review focuses on the interplay between drugs and the kidney in premature neonates.