New antibiotic dosing in infants

Dried Blood Spots Sampling and Population Pharmacokinetic Modeling for Dosing Optimization of Piperacillin in Chinese Neonates

Piperacillin is commonly used off-label in neonates for the treatment of bacterial infections. This study aimed to assess a dried blood spots (DBS)-based microsampling strategy for supporting population pharmacokinetics and treatment optimization of piperacillin in Chinese neonates. DBS samples from neonatal patients were collected at predefined intervals. Drug blood concentrations were quantified using a validated ultra-high-performance liquid chromatography-tandem mass spectrometry method. A population pharmacokinetic model was developed using a nonlinear mixed-effects modeling approach. The pharmacokinetic/pharmacodynamics (PK/PD) target was 75% of the time with the unbound drug plasma concentration above the minimum inhibitory concentration (fT>MIC), with a toxicity threshold of unbound drug plasma trough concentration above 64 mg/L. A total of 45 piperacillin samples from 24 neonates were collected. The pharmacokinetics of piperacillin was described using a one-compartment model with postmenstrual age (PMA) as the most significant covariate on clearance. Simulations showed that dosing regimens achieving >90% PK/PD target attainment with <10% risk of possible toxicity were: PMA 33-35 weeks (50 mg/kg q12h), 35-37 weeks (50 mg/kg q8h), and 37-41 weeks (50 mg/kg q6h). In conclusion, Using DBS sampling, we developed a population pharmacokinetic model of piperacillin in Chinese neonates, incorporating PMA to determine optimal dosing regimens.

Dual alarmin-receptor-specific targeting peptide systems for treatment of sepsis

The pathophysiology of sepsis is characterized by a systemic inflammatory response to infection; however, the cytokine blockade that targets a specific early inflammatory mediator, such as tumor necrosis factor, has shown disappointing results in clinical trials. During sepsis, excessive endotoxins are internalized into the cytoplasm of immune cells, resulting in dysregulated pyroptotic cell death, which induces the leakage of late mediator alarmins such as HMGB1 and PTX3. As late mediators of lethal sepsis, overwhelming amounts of alarmins bind to high-affinity TLR4/MD2 and low-affinity RAGE receptors, thereby amplifying inflammation during early-stage sepsis. In this study, we developed a novel alarmin/receptor-targeting system using a TLR4/MD2/RAGE-blocking peptide (TMR peptide) derived from the HMGB1/PTX3-receptors interacting motifs. The TMR peptide successfully attenuated HMGB1/PTX3- and LPS-mediated inflammatory cytokine production by impairing its interactions with TLR4 and RAGE. Moreover, we developed TMR peptide-conjugated liposomes (TMR-Lipo) to improve the peptide pharmacokinetics. In combination therapy, moderately antibiotic-loaded TMR-Lipo demonstrated a significant therapeutic effect in a mouse model of cecal ligation- and puncture-induced sepsis. The identification of these peptides will pave the way for the development of novel pharmacological tools for sepsis therapy.

[Update Perioperative Antibiotic Prophylaxis in Neonatology]

This narrative review discusses basic principles of the perioperative antibiotic prophylaxis (PAP) in premature and at term newborns and refers to some particularities concerning the indication and dosing issues. Although this is a vulnerable patient population, the spectrum of activity should not be unnecessarily broad and the regular PAP must not be prolonged beyond 24 hours.

CDC Guidelines for the Prevention and Treatment of Anthrax, 2023

This report updates previous CDC guidelines and recommendations on preferred prevention and treatment regimens regarding naturally occurring anthrax. Also provided are a wide range of alternative regimens to first-line antimicrobial drugs for use if patients have contraindications or intolerances or after a wide-area aerosol release of

Bacillus anthracis spores if resources become limited or a multidrug-resistant B. anthracis strain is used (Hendricks KA, Wright ME, Shadomy SV, et al.; Workgroup on Anthrax Clinical Guidelines. Centers for Disease Control and Prevention expert panel meetings on prevention and treatment of anthrax in adults. Emerg Infect Dis 2014;20:e130687; Meaney-Delman D, Rasmussen SA, Beigi RH, et al. Prophylaxis and treatment of anthrax in pregnant women. Obstet Gynecol 2013;122:885-900; Bradley JS, Peacock G, Krug SE, et al. Pediatric anthrax clinical management. Pediatrics 2014;133:e1411-36). Specifically, this report updates antimicrobial drug and antitoxin use for both postexposure prophylaxis (PEP) and treatment from these previous guidelines best practices and is based on systematic reviews of the literature regarding 1) in vitro antimicrobial drug activity against B. anthracis; 2) in vivo antimicrobial drug efficacy for PEP and treatment; 3) in vivo and human antitoxin efficacy for PEP, treatment, or both; and 4) human survival after antimicrobial drug PEP and treatment of localized anthrax, systemic anthrax, and anthrax meningitis.

Changes from previous CDC guidelines and recommendations include an expanded list of alternative antimicrobial drugs to use when first-line antimicrobial drugs are contraindicated or not tolerated or after a bioterrorism event when first-line antimicrobial drugs are depleted or ineffective against a genetically engineered resistant

B. anthracis strain. In addition, these updated guidelines include new recommendations regarding special considerations for the diagnosis and treatment of anthrax meningitis, including comorbid, social, and clinical predictors of anthrax meningitis. The previously published CDC guidelines and recommendations described potentially beneficial critical care measures and clinical assessment tools and procedures for persons with anthrax, which have not changed and are not addressed in this update. In addition, no changes were made to the Advisory Committee on Immunization Practices recommendations for use of anthrax vaccine (Bower WA, Schiffer J, Atmar RL, et al. Use of anthrax vaccine in the United States: recommendations of the Advisory Committee on Immunization Practices, 2019. MMWR Recomm Rep 2019;68[No. RR-4]:1-14). The updated guidelines in this report can be used by health care providers to prevent and treat anthrax and guide emergency preparedness officials and planners as they develop and update plans for a wide-area aerosol release of B. anthracis.

Population Pharmacokinetics and Dosage Optimization of Linezolid in Critically Ill Pediatric Patients

Linezolid is an oxazolidinone antibiotic exhibiting efficacy against multidrug-resistant (MDR) Gram-positive-related infections. However, its population pharmacokinetic (PopPK) profile in Chinese critically ill children has not been characterized. Optimal dosing regimens should be established according to the PopPK/pharmacodynamic(PD) properties of linezolid in the specific population. This work aims to describe the pharmacokinetic (PK) properties of linezolid, assess the factors affecting interpatient variability, and establish an optimized regimen for children in pediatric intensive care unit (PICU). A single-center, prospective, open-labeled PK study was performed. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was applied to measure the plasma levels during linezolid treatment. PopPK analysis was conducted using Phoenix NLME software. Sixty-three critically ill pediatric patients were included. The data showed good fit for a two-compartment model with linear elimination. Body weight and aspartate aminotransferase (AST) were the most significant covariates explaining variabilities in linezolid PK for the pediatric population. Therapeutic target was defined as the ratio of the area under drug plasma concentration-time curve over 24 h to minimum inhibitory concentration (AUC/MIC) of >80. Different dosing regimens were evaluated using Monte Carlo simulation to determine the optimal dosage strategy for linezolid. Although the probability of target attainment (PTA) was high (>96%) for 10 mg/kg every 8 h at MIC≤1 mg/L, it was lower than 70% at MIC>1 mg/L. Thus, the dosing regimen required adjustment. When the dosing regimen was adjusted to 15 mg/kg every 6 h, the PTA increased from 63.6% to 94.6% at MIC=2 mg/L, thereby indicating higher treatment success. Children with AST of >40 U/L had significant higher AUC than those with AST of ≤40 U/L (205.45 vs. 159.96). Therefore, dosage adjustment was required according to the AST levels. The PopPK characteristics of linezolid in critically ill children were evaluated, and an optimal dosage regimen was constructed based on developmental PopPK/PD model and simulation. (This study has been registered in the Chinese Clinical Trial Registry under no. ChiCTR1900021386.).

Simplified Dosing Regimens for Gentamicin in Neonatal Sepsis

Background: The effectiveness of antibiotics for the treatment of severe bacterial infections in newborns in resource-limited settings has been determined by empirical evidence. However, such an approach does not warrant optimal exposure to antibiotic agents, which are known to show different disposition characteristics in this population. Here we evaluate the rationale for a simplified regimen of gentamicin taking into account the effect of body size and organ maturation on pharmacokinetics. The analysis is supported by efficacy data from a series of clinical trials in this population.

Methods: A previously published pharmacokinetic model was used to simulate gentamicin concentration vs. time profiles in a virtual cohort of neonates. Model predictive performance was assessed by supplementary external validation procedures using therapeutic drug monitoring data collected in neonates and young infants with or without sepsis. Subsequently, clinical trial simulations were performed to characterize the exposure to intra-muscular gentamicin after a q.d. regimen. The selection of a simplified regimen was based on peak and trough drug levels during the course of treatment.

Results: In contrast to current World Health Organization guidelines, which recommend gentamicin doses between 5 and 7.5 mg/kg, our analysis shows that gentamicin can be used as a fixed dose regimen according to three weight-bands: 10 mg for patients with body weight <2.5 kg, 16 mg for patients with body weight between 2.5 and 4 kg, and 30 mg for those with body weight >4 kg.

Conclusion: The choice of the dose of an antibiotic must be supported by a strong scientific rationale, taking into account the differences in drug disposition in the target patient population. Our analysis reveals that a simplified regimen is feasible and could be used in resource-limited settings for the treatment of sepsis in neonates and young infants with sepsis aged 0–59 days.

Antimicrobial Stewardship in Neonates: Challenges and Opportunities

Neonatal infections result in significant morbidity and mortality. Antibiotics are vital for the treatment of infections but disrupt the neonatal microbiome, put the infant at risk for an adverse drug reaction, and may lead to the development of antibiotic resistance. Immediately after birth, clinicians must determine which infants require empiric antibiotics. Online risk stratification tools may provide a superior approach to decision trees. In infants who require empiric therapy for early-onset sepsis, ampicillin and an aminoglycoside with dosing based on recent pharmacokinetic studies represents the most appropriate first-line agents; third-generation cephalosporins should be reserved for patients with a high likelihood of Gram-negative meningitis. An antistaphylococcal penicillin and gentamicin should be utilized for suspected late-onset sepsis. Vancomycin and other broad-spectrum agents are reserved for patients with a history of resistant organisms. Antibiotic duration should be guided by understanding the clinical indications and obtaining the necessary cultures appropriately (i.e., adequate volume blood cultures). In the absence of a positive culture, antibiotic duration should often be limited. Individual institutions should leverage a multidisciplinary, interprofessional team to identify opportunities for antimicrobial stewardship. A collaborative, transparent system is required to change unit culture and generate a sustained impact on antibiotic utilization with optimal patient outcomes.

Population Pharmacokinetics and Dosing Optimization of Azithromycin in Children with Community-Acquired Pneumonia

Azithromycin is extensively used in children with community-acquired pneumonia (CAP). Currently, the intravenous azithromycin is used off-label in children partly due to lacking of pharmacokinetic data. Our objective was to evaluate the population pharmacokinetics (PPK) and optimize dose strategy in order to improve treatment in this distinctive population. This was a prospective, multicenter, open-labeled pharmacokinetic study. Blood samples were collected from hospitalized pediatric patients and concentrations were determined by liquid chromatography-tandem mass spectrometry (LC-MS/MS). PPK analysis was conducted using NONMEM software. The pharmacokinetic data from 95 pediatric patients (age range, 2.1 to 11.7 years) were available for analysis. The PPK was best fitted by a two-compartment model with linear elimination. Covariate analysis verified that body weight and alanine aminotransferase (ALT) had significant effects on azithromycin pharmacokinetics, yielding a 24% decrease of clearance in patients with ALT of >40. Monte Carlo simulation showed that for children with normal liver function, a loading-dose strategy (a loading dose of 15 mg/kg of body weight followed by maintenance doses of 10 mg/kg) would achieve the ratio of the area under free drug plasma concentration-time curve over 24 h (fAUC) to MIC₉₀ (fAUC/MIC) target of 3 h in 53.2% of hypothetical patients, using a normative MIC susceptibility breakpoint of 2 mg/liter. For children with ALT of >40, the proposed dose needed to decrease by 15% to achieve comparable exposure. The corresponding risk of overdose for the recommended dosing regimen was less than 5.8%. In conclusion, the PPK of azithromycin was evaluated in children with CAP and an optimal dosing regimen was constructed based on developmental pharmacokinetic-pharmacodynamic modeling and simulation.

Dosing antibiotics in neonates: review of the pharmacokinetic data

Antibiotics are often used in neonates despite the absence of relevant dosing information in drug labels. For neonatal dosing, clinicians must extrapolate data from studies for adults and older children, who have strikingly different physiologies. As a result, dosing extrapolation can lead to increased toxicity or efficacy failures in neonates. Driven by these differences and recent legislation mandating the study of drugs in children and neonates, an increasing number of pharmacokinetic studies of antibiotics are being performed in neonates. These studies have led to new dosing recommendations with particular consideration for neonate body size and maturation. Herein, we highlight the available pharmacokinetic data for commonly used systemic antibiotics in neonates.