Pharmacokinetics, pharmacodynamics, and Monte Carlo simulation: selecting the best antimicrobial dose to treat an infection

Treatment of mild to moderate community-acquired pneumonia in previously healthy children: an Italian intersociety consensus (SIPPS-SIP-SITIP-FIMP-SIAIP-SIMRI-FIMMG-SIMG)

Community-acquired pneumonia (CAP) is an acute infection of the lung parenchyma acquired outside the hospital or other healthcare settings, typically affecting previously healthy individuals. This intersociety consensus aims to provide evidence-based recommendations for the antibiotic treatment of mild to moderate CAP in previously healthy children in Italy.A systematic review was conducted to identify the most recent and relevant evidence. Embase, Scopus, PubMed, and Cochrane databases were systematically screened, with a date restriction from 2012 to April 2024, but without language limitations. The review included studies conducted in high-income countries on antibiotic therapy in children over 3 months of age diagnosed with mild-moderate CAP. The certainty of evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methods. The final recommendations were obtained through a Delphi consensus of an expert panel.Amoxicillin is the first-line treatment if the child is at least immunized against Haemophilus influenzae type b (low/very low quality of evidence, strong recommendations), while amoxicillin-clavulanate or second- or third-generation cephalosporins should be prescribed for those unimmunized or with incomplete immunization coverage for both H. influenzae type b and Streptococcus pneumoniae (low/very low quality of evidence, strong recommendations). Macrolides should be considered in addition to amoxicillin in children over 5 years old, if symptoms persist and the clinical condition remains good after 48 h of therapy (low/very low quality of evidence, strong recommendations). The dosage of amoxicillin is 90 mg/kg/day divided in three doses, although two doses could be considered to improve compliance (moderate quality of evidence, weak recommendations). A five-day duration of therapy is recommended, with clinical monitoring and re-assessment approximately 72 h after the start of antibiotic treatment to evaluate symptom resolution (moderate quality of evidence, strong recommendations).To improve the management of CAP in pediatric patients, we have developed this consensus based on a thorough review of the best available evidence and extensive discussions with an expert panel. However, further efforts are needed. Future research should focus on enhancing diagnostic accuracy, optimizing antibiotic utilization, comparing the efficacy of different antibiotic regimens, and determining the optimal dosage and duration of treatment in different setting.

Pharmacokinetic-pharmacodynamic analysis of cefmetazole against extended-spectrum β-lactamase-producing Enterobacteriaceae in dogs using Monte Carlo Simulation

Introduction

The spread of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) is a serious concern in companion animal medicine owing to their ability to develop multidrug resistance. Cefmetazole (CMZ) is a candidate drug for treating ESBL-E infections; however, its regimen in dogs has not been established. In this study, we investigated the pharmacokinetic (PK) indices of CMZ in dogs and performed PK-pharmacodynamic (PD) analyses using Monte Carlo Simulation (MCS).

Methods

In total, six healthy dogs received an intravenous bolus dose of CMZ (40 mg/kg body weight). Serum CMZ concentrations were evaluated using liquid chromatography-mass spectrometry, and PK indices were determined based on non-compartmental analysis. The PK-PD cut-off (COPD) values were calculated as the highest minimum inhibitory concentration (MIC) that achieved ≥90% probability of target attainment for a target value of unbounded drug concentration exceeding 40% of the dosing interval. The cumulative fraction of response (CFR) was calculated based on the MIC distribution of wild-type ESBL-E from companion animals.

Results

The area under the concentration-time curve and elimination half-time were 103.36 ± 7.49 mg·h/L and 0.84 ± 0.07 h, respectively. MCS analysis revealed that COPD values for regimens of 40 mg/kg q12, q8h, and q6h were ≤ 0.5, ≤2, and ≤ 4 μg/mL, respectively. A regimen of 40 mg/kg q6h was estimated to achieve a CFR of 80-90% for Escherichia coli and Klebsiella pneumoniae. By contrast, all regimens exhibited a CFR of ≤70% for Proteus mirabilis and Enterobacter cloacae.

Discussion

We conclude that CMZ at 40 mg/kg q6h could be a viable treatment regimen for dogs infected with ESBL-producing Escherichia coli and Klebsiella pneumoniae.

Shedding Light on Amoxicillin, Amoxicillin-clavulanate, and Cephalexin Dosing in Children from a Pharmacist's Perspective

Selection of an antibiotic and dosing regimen requires consideration of multiple factors including microbiological data, site of infection, pharmacokinetics, and how it relates to the pharmacodynamic target. Given the multiple dosage regimens of amoxicillin with/without clavulanate and cephalexin, we review the principles of dose selection from a pharmacist's perspective.

Optimizing Clinical Outcomes Through Rational Dosing Strategies: Roles of Pharmacokinetic/Pharmacodynamic Modeling Tools

Significant progress in previous decades has led to several methodologies developed to facilitate the design of optimal antimicrobial dosing. In this review, we highlight common pharmacokinetic/pharmacodynamic (PKPD) modeling techniques and their roles in guiding rational dosing regimen design. In the early drug development phases, dose fractionation studies identify the PKPD index most closely associated with bacterial killing. Once discerned, this index is linked to clinical efficacy end points, and classification and regression tree analysis can be used to define the PKPD target goal. Monte Carlo simulations integrate PKPD and microbiological data to identify dosing strategies with a high probability of achieving the established PKPD target. Results then determine dosing regimens to investigate and/or validate the findings of randomized controlled trials. Further improvements in PKPD modeling could lead to an era of precision dosing and personalized therapeutics.

A Comprehensive Overview of Antibiotic Selection and the Factors Affecting It

In order to prescribe an antibiotic, a physician must go through a series of decision-making processes that involve both the drug and the host. In this review article, we outline exactly what those decision-making processes are and some of their limitations. Before a medication can be prescribed, a physician has to determine if the antibiotic works against the host pathogen. To do this, basic science techniques are employed including phenotypic methods such as broth dilution methods, Kirby-Bauer susceptibility testing, Epsilometer test (E-test), and genotypic methods such as the new and upcoming automated tests. After determining if a drug has potential to work, the physician must consider the drug’s mechanism of action in order to determine a dosing regimen. Some groups of drugs should be administered at high concentrations infrequently, others should be given more frequently in smaller doses, and others lie somewhere between this spectrum. Finally, external factors such as the patient's age, especially for pediatrics and geriatrics patients, need to be considered, as these groups have the highest health care burden but are among the most vulnerable when it comes to the side effects of drugs.

Which Analysis Approach Is Adequate to Leverage Clinical Microdialysis Data? A Quantitative Comparison to Investigate Exposure and Reponse Exemplified by Levofloxacin

Purpose

Systematic comparison of analysis methods of clinical microdialysis data for impact on target-site drug exposure and response.

Methods

39 individuals received a 500 mg levofloxacin short-term infusion followed by 24-h dense sampling in plasma and microdialysate collection in interstitial space fluid (ISF). ISF concentrations were leveraged using non-compartmental (NCA) and compartmental analysis (CA) via (ii) relative recovery correction at midpoint of the collection interval (midpoint-NCA, midpoint-CA) and (ii) dialysate-based integrals of time (integral-CA). Exposure and adequacy of community-acquired pneumonia (CAP) therapy via pharmacokinetic/pharmacodynamic target-attainment (PTA) analysis were compared between approaches.

Results

Individual AUC_ISF estimates strongly varied for midpoint-NCA and midpoint-CA (≥52.3%CV) versus integral-CA (≤32.9%CV) owing to separation of variability in PK parameters (midpoint-CA = 46.5%–143%CV_PK, integral-CA = 26.4%–72.6%CV_PK) from recovery-related variability only in integral-CA (41.0%–50.3%CV_recovery). This also led to increased variability of AUC_plasma for midpoint-CA (56.0%CV) versus midpoint-NCA and integral-CA (≤33.0%CV), and inaccuracy of predictive model performance of midpoint-CA in plasma (visual predictive check). PTA analysis translated into 33% of evaluated patient cases being at risk of incorrectly rejecting recommended dosing regimens at CAP-related epidemiological cut-off values.

Conclusions

Integral-CA proved most appropriate to characterise clinical pharmacokinetics- and microdialysis-related variability. Employing this knowledge will improve the understanding of drug target-site PK for therapeutic decision-making.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11095-021-02994-1.

Advancing pediatric antimicrobial stewardship: Has pharmacodynamic dosing for gram-negative infections taken effect?

Objective:

To characterize pharmacodynamic dosing strategies used at children’s hospitals using a national survey.

Design:

Survey.

Setting:

Children’s hospitals.

Participants:

Volunteer sample of antimicrobial stewardship program (ASP) respondents.

Methods:

A nationwide survey was conducted to gain greater insight into the current adoption of nontraditional dosing methods and monitoring of select β-lactam and fluoroquinolone antibiotics used to treat serious gram-negative infections in pediatric populations. The survey was performed through the Sharing Antimicrobial Reports for Pediatric Stewardship (SHARPS) Collaborative.

Results:

Of the 75 children’s hospitals that responded, 68% of programs reported adoption of pharmacodynamically optimized dosing using prolonged β-lactam infusions and 35% using continuous β-lactam infusions, although use was infrequent. Factors including routine MIC monitoring and formal postgraduate training and board certification of ASP pharmacists were associated with increased utilization of pharmacodynamic dosing. In addition, 60% of programs reported using pharmacodynamically optimized ciprofloxacin and 14% reported using pharmacodynamically optimized levofloxacin. Only 20% of programs monitored β-lactam levels; they commonly cited lack of published guidance, practitioner experience, and laboratomory support as reasons for lack of utilization. Less physician time dedicated to ASP programs was associated with lower adoption of optimized dosing.

Conclusions:

Use of pharmacodynamic dosing through prolonged and continuous infusions of β-lactams have not yet been routinely adopted at children’s hospitals. Further guidance from trials and literature are needed to continue to guide pediatric pharmacodynamic dosing efforts. Children’s hospitals should utilize these data to compare practices and to prioritize further research and education efforts.

How to Treat Sepsis in the Background of Resistance?: Role of Pharmacodynamics / Pharmacokinetics in Treating Sepsis

Though a decline has been seen in child mortality and morbidity over the last decades, sepsis in neonates and infants remains a major cause of death. Optimal use of antibiotics in sepsis management is a key factor which can further reduce the number of poor clinical outcomes. Selecting the right antibiotic to which the offending bacteria is susceptible and administrating the antibiotic within the first hour can save many lives. However, the pharmacokinetic profile of an antibiotic is affected by developmental changes such as capacity of drug metabolizing enzymes and maturation of organ function. This can affect antibiotic exposure and response in neonates and infants. While suspecting sepsis, the primary focus of empiric treatment during the initial phase is to assure efficacy and it must be broad based to cover all suspected pathogens. Once the bacterial etiology is confirmed as a cause of sepsis and the in vitro antibiotic susceptibility is established, targeted treatment can be started which ensures optimal balance between efficacy and safety.

Optimizing Antibiotic Drug Therapy in Pediatrics: Current State and Future Needs

The selection of the right antibiotic and right dose necessitates clinicians understand the contribution of pharmacokinetic variability stemming from age-related physiologic maturation and the pharmacodynamics to optimize drug exposure for clinical response. The complexity of selecting the right dose arises from the multiplicity of pediatric age groups, from premature neonates to adolescents. Body size and age (which relate to organ function) must be incorporated to optimize antibiotic dosing in this vulnerable population. In the effort to optimize and individualize drug dosing regimens, clinical pharmacometrics that incorporate population-based pharmacokinetic modeling, Bayesian estimation, and Monte Carlo simulations are utilized as a quantitative approach to understanding and predicting the pharmacology and clinical and microbiologic efficacy of antibiotics. In addition, opportunistic study designs and alternative blood sampling strategies can serve as practical approaches to ensure successful conduct of pediatric studies. This review article examines relevant literature on optimization of antibiotic pharmacotherapy in pediatric populations published within the last decade. Specific pediatric antibiotic data, including beta-lactam antibiotics, aminoglycosides, and vancomycin, are critically evaluated.

Recommendations and guidelines for the treatment of pneumonia in Taiwan

Pneumonia is a leading cause of death worldwide, ranking third both globally and in Taiwan. This guideline was prepared by the 2017 Guidelines Recommendations for Evidence-based Antimicrobial agents use in Taiwan (GREAT) working group, formed under the auspices of the Infectious Diseases Society of Taiwan (IDST). A consensus meeting was held jointly by the IDST, Taiwan Society of Pulmonary and Critical Care Medicine (TSPCCM), the Medical Foundation in Memory of Dr. Deh-Lin Cheng, the Foundation of Professor Wei-Chuan Hsieh for Infectious Diseases Research and Education and CY Lee's Research Foundation for Pediatric Infectious Diseases and Vaccines. The final guideline was endorsed by the IDST and TSPCCM. The major differences between this guideline and the 2007 version include the following: the use of GRADE methodology for the evaluation of available evidence whenever applicable, the specific inclusion of healthcare-associated pneumonia as a category due to the unique medical system in Taiwan and inclusion of recommendations for treatment of pediatric pneumonia. This guideline includes the epidemiology and recommendations of antimicrobial treatment of community-acquired pneumonia, hospital-acquired pneumonia, ventilator-associated pneumonia, healthcare-associated pneumonia in adults and pediatric pneumonia.

Amikacin target achievement in adult cystic fibrosis patients utilizing Monte Carlo simulation

AIM

Pseudomonas aeruginosa (PsA) is a common pathogen in cystic fibrosis (CF). Management of an acute pulmonary exacerbation (APE) caused by PsA is dual anti-pseudomonal antibiotics, a beta-lactam plus aminoglycoside. Aminoglycoside dosing in CF differs from the general population due to altered pharmacokinetics. The primary objective of this study was to utilize pharmacokinetic data from adult CF patients that received amikacin to determine the probability of target attainment for APEs caused by PsA.

METHODS

This was a single-center, non-randomized, retrospective cohort study of patients >18 years with CF that received intravenous amikacin between January 2010 and July 2016. Amikacin dose, frequency, and serum concentrations were used to calculate pharmacokinetic parameters assuming a one-compartment model. Monte Carlo simulation was conducted with MIC values from CF patients with a PsA positive sputum culture between January 2014 and September 2016 to predict concentration-time profiles for different doses of amikacin.

RESULTS

This study included pharmacokinetic parameters for 14 amikacin courses administered to six unique patients. The average empiric dose of amikacin was 24.3 ± 14.6 mg/kg, achieving a peak:MIC ratio ≥8 at a rate of 37% (median 5.87; IQR 3.05-10.96). A dose of 45 mg/kg/day was needed to achieve target peak:MIC ratios 90% of the time for a PsA MIC of 8 mg/L.

CONCLUSION

Our data suggests it may not be clinically feasible to utilize amikacin for PsA isolates with a MIC of 16 mg/L. Current guideline dosing recommendations of amikacin 30-35 mg/kg/day are only adequate for PsA with a MIC ≤4 mg/L.

Corneal epithelial permeability to fluorescein in humans by a multi-drop method

Purpose

The permeability of the corneal epithelium to fluorescein P_dc is an indicator of the health of the ocular surface. It can be measured in a clinical setting by determining the accumulation of fluorescein in the stroma following administration of the dye on the ocular surface. Here we demonstrate a new multi-drop method for the measurement of P_dc by a spot fluorometer.

Methods

Twenty-nine healthy participants were recruited for this study. First, a probe-drop of fluorescein (0.35%, 2 μL) was instilled on the conjunctiva. The clearance of the dye from the tears was immediately measured using the fluorometer. Following this, two loading drops (2%; 6 μL each) were administered 10 min apart. Fifteen minutes later, the ocular surface was washed and fluorescence from the stroma F_s was measured. Permeability was calculated using P_dc = (Q x F_s)/ (2 x AUC), where Q is the stromal thickness and AUC is the area under the fluorescence vs. time curve for the loading drops.

Results

After the probe drop, the tear fluorescence followed an exponential decay (elimination rate constant; k_d = 0.41 ± 0.28 per min; 49 eyes of 29 subjects), but the increase in F_s was negligible. However, after the loading drops, the measured F_s was ~ 20-fold higher than the autofluorescence and could be recorded at a high signal to noise ratio (SNR > 40). The intra-subject variability of k_d was insignificant. Since fluorescein undergoes concentration quenching at > 0.5%, the value of AUC for the loading drops was estimated by scaling the AUC of the probe drop. The calculated P_dc was 0.54 ± 0.54 nm/sec (n = 49). A Monte Carlo simulation of the model for the multi-drop protocol confirmed the robustness of the estimated P_dc.

Conclusions

The new multi-drop method can be used in place of the single-drop approach. It can overcome a lack of sensitivity in fluorometers of high axial resolution. The P_dc estimated by the multi-drop method is ~ 11-fold higher than previously reported but closer to the value reported for other drugs with equivalent octanol/water partition coefficient.

A Monte Carlo Simulation Approach for Beta-Lactam Dosing in Critically Ill Patients Receiving Prolonged Intermittent Renal Replacement Therapy

Cefepime, ceftazidime, and piperacillin/tazobactam are commonly used beta-lactam antibiotics in the critical care setting. For critically ill patients receiving prolonged intermittent renal replacement therapy (PIRRT), limited pharmacokinetic data are available to inform clinicians on the dosing of these agents. Monte Carlo simulations (MCS) can be used to guide drug dosing when pharmacokinetic trials are not feasible. For each antibiotic, MCS using previously published pharmacokinetic data derived from critically ill patients was used to evaluate multiple dosing regimens in 4 different prolonged intermittent renal replacement therapy effluent rates and prolonged intermittent renal replacement therapy duration combinations (4 L/h × 10 hours or 5 L/h × 8 hours in hemodialysis and hemofiltration modes). Antibiotic regimens were also modeled depending on whether drugs were administered during or well before prolonged intermittent renal replacement therapy therapy commenced. The probability of target attainment (PTA) was calculated using each antibiotic's pharmacodynamic target during the first 48 hours of therapy. Optimal doses were defined as the smallest daily dose achieving ≥90% probability of target attainment in all prolonged intermittent renal replacement therapy effluent and duration combinations. Cefepime 1 g every 6 hours following a 2 g loading dose, ceftazidime 2 g every 12 hours, and piperacillin/tazobactam 4.5 g every 6 hours attained the desired pharmacodynamic target in ≥90% of modeled prolonged intermittent renal replacement therapy patients. Alternatively, if an every 6-hours cefepime regimen is not desired, the cefepime 2 g pre-prolonged intermittent renal replacement therapy and 3 g post-prolonged intermittent renal replacement therapy regimen also met targets. For ceftazidime, 1 g every 6 hours or 3 g continuous infusion following a 2 g loading dose also met targets. These recommended doses provide simple regimens that are likely to achieve the pharmacodynamics target while yielding the least overall drug exposure, which should result in lower toxicity rates. These findings should be validated in the clinical setting.

Effects of clinical pathway implementation on antibiotic prescriptions for pediatric community-acquired pneumonia

BACKGROUND

Italian pediatric antimicrobial prescription rates are among the highest in Europe. As a first step in an Antimicrobial Stewardship Program, we implemented a Clinical Pathway (CP) for Community Acquired Pneumonia with the aim of decreasing overall prescription of antibiotics, especially broad-spectrum.

MATERIALS AND METHODS

The CP was implemented on 10/01/2015. We collected antibiotic prescribing and outcomes data from children aged 3 months-15 years diagnosed with CAP from 10/15/2014 to 04/15/2015 (pre-intervention period) and from 10/15/2015 to 04/15/2016 (post-intervention period). We assessed antibiotic prescription differences pre- and post-CP, including rates, breadth of spectrum, and duration of therapy. We also compared length of hospital stay for inpatients and treatment failure for inpatients and outpatients. Chi-square and Fisher's exact test were used to compare categorical variables and Wilcoxon rank sum test was used to compare quantitative outcomes.

RESULTS

120 pre- and 86 post-intervention clinic visits were identified with a diagnosis of CAP. In outpatients, we observed a decrease in broad-spectrum regimens (50% pre-CP vs. 26.8% post-CP, p = 0.02), in particular macrolides, and an increase in narrow-spectrum (amoxicillin) post-CP. Post-CP children received fewer antibiotic courses (median DOT from 10 pre-CP to 8 post-CP, p<0.0001) for fewer days (median LOT from 10 pre-CP to 8 post-CP, p<0.0001) than their pre-CP counterparts. Physicians prescribed narrow-spectrum monotherapy more frequently than broad-spectrum combination therapy (DOT/LOT ratio 1.157 pre-CP vs. 1.065 post-CP). No difference in treatment failure was reported before and after implementation (2.3% pre-CP vs. 11.8% post-CP, p = 0.29). Among inpatients we also noted a decrease in broad-spectrum regimens (100% pre-CP vs. 66.7% post-CP, p = 0.02) and the introduction of narrow-spectrum regimens (0% pre-CP vs. 33.3% post-CP, p = 0.02) post-CP. Hospitalized patients received fewer antibiotic courses post-CP (median DOT from 18.5 pre-CP to 10 post-CP, p = 0.004), while there was no statistical difference in length of therapy (median LOT from 11 pre-CP to 10 post-CP, p = 0.06). Days of broad spectrum therapy were notably lower post-CP (median bsDOT from 17 pre-CP to 4.5 post-CP, p <0.0001). No difference in treatment failure was reported before and after CP implementation (16.7% pre-CP vs. 15.4% post-CP, p = 1).

CONCLUSIONS

Introduction of a CP for CAP in a Pediatric Emergency Department led to reduction of broad-spectrum antibiotic prescriptions, of combination therapy and of duration of treatment both for outpatients and inpatients.

Modelling and simulation of edoxaban exposure and response relationships in patients with atrial fibrillation

Edoxaban is a novel, orally available, highly specific direct inhibitor of factor Xa and is currently being developed for the treatment and prevention of venous thromboembolism and prevention of stroke and systemic embolism in patients with non-valvular atrial fibrillation (NVAF). The objectives of the present analyses were to characterise edoxaban population pharmacokinetics (PPK) and identify potential intrinsic and extrinsic factors affecting variability in edoxaban exposure, determine if there are relationships between edoxaban pharmacokinetics or biomarkers and the risk of bleeding in patients with NVAF using an exposure-response model, and to use the PPK and exposure-response model to support dose selection for a phase III trial of edoxaban in patients with NVAF. PPK analysis of data from 1,281 edoxaban-dosed subjects with intrinsic factors such as renal impairment or NVAF and extrinsic factors such as concomitant medications revealed significant effects of renal impairment and concomitant strong P-glycoprotein (P-gp) inhibitors on the pharmacokinetics of edoxaban. Exposure-response analysis found that in patients with NVAF, the incidence of bleeding events increased significantly with increasing edoxaban exposure, with steady-state minimum concentration (Cmin,ss) showing the strongest association. Clinical trial simulations of bleeding incidence were used to select 30 mg and 60 mg once-daily edoxaban with 50% dose reductions for patients with moderate renal impairment or receiving concomitant strong P-gp inhibitors as the treatment regimens in the ENGAGE AF-TIMI 48 (NCT00781391) trial.

The results of this study were previously presented at the 2009 International Society on Thrombosis and Haemostasis, July 2009, Boston, Massachusetts, USA.

The Impact of Prior Antibiotic Therapy on Outcomes in Children Hospitalized for Community-Acquired Pneumonia

Here, we review current available literature regarding the effect of prior antibiotic treatment on outcomes of children hospitalized for community-acquired pneumonia (CAP). To date, no prospective trial has reported information regarding morbidity or mortality in this group of patients. Retrospective studies have provided evidence for the advantage of treatment with broad-spectrum antibiotics in children who failed prior antibiotic therapy. We discuss the changing epidemiology of CAP in the post PCV13 and Hib vaccines era and its relevance to the outcome of pediatric patients hospitalized for CAP. Current studies still report Streptococcus pneumoniae as the most common typical bacterial causative agent in pediatric CAP. However, in children who fail to respond to guideline directed antibiotic therapy, a non-pneumococcal, possibly one of several β-lactam resistant causative bacterial agents should be considered thus clarifying the advantage for broad-spectrum empirical antibiotic treatment in this group of patients.

Antibiotic treatment for children hospitalized with community-acquired pneumonia after oral therapy

OBJECTIVE

To compare the outcome of treatment with narrow spectrum versus broad spectrum antibiotics in children hospitalized with community-acquired pneumonia (CAP) who received oral antibiotic treatment prior to their hospitalization.

DESIGN, SETTING, AND PATIENTS

A review of all previously healthy children from 3 months to 18 years with non-complicated CAP who received an oral antibiotic course in the community and were admitted from 2003 to 2008 to our pediatric departments.

MAIN OUTCOME MEASURES

Clinical course and outcome parameters were compared for treatment with narrow and broad spectrum antibiotics.

RESULTS

Of the 337 children admitted with non-complicated CAP after an oral antibiotic treatment course in the community, 235 were treated with broad spectrum, and 102 with narrow spectrum antibiotics. The two groups were similar regarding age, sex, days of fever prior to admission, type of preadmission oral antibiotic treatment, and laboratory indices at admission (P > 0.1). The broad spectrum-treated group had significantly better outcomes in terms of number of febrile days (1.2 ± 1.1 vs. 1.7 ± 1.6, P < 0.001), number of days treated with intravenous antibiotics (3.1 ± 1.3 vs. 3.9 ± 2.0, P < 0.001), and days of hospitalization (3.5 ± 1.5 vs. 4.2 ± 2.0, P < 0.001). The odds ratio for remaining hospitalized at 72 hr and 7 days was significantly higher for the narrow spectrum group (2.0 and 5.5 respectively, P < 0.05).

CONCLUSIONS

In previously healthy children hospitalized with CAP after oral antibiotic treatment in the community treatment with broad spectrum antibiotics showed better outcome. Prospective studies are needed for appropriate recommendation.

Antifungal pharmacokinetics and pharmacodynamics

Successful treatment of infectious diseases requires choice of the most suitable antimicrobial agent, comprising consideration of drug pharmacokinetics (PK), including penetration into infection site, pathogen susceptibility, optimal route of drug administration, drug dose, frequency of administration, duration of therapy, and drug toxicity. Antimicrobial pharmacokinetic/pharmacodynamic (PK/PD) studies consider these variables and have been useful in drug development, optimizing dosing regimens, determining susceptibility breakpoints, and limiting toxicity of antifungal therapy. Here the concepts of antifungal PK/PD studies are reviewed, with emphasis on methodology and application. The initial sections of this review focus on principles and methodology. Then the pharmacodynamics of each major antifungal drug class (polyenes, flucytosine, azoles, and echinocandins) is discussed. Finally, the review discusses novel areas of pharmacodynamic investigation in the study and application of combination therapy.

Randomized controlled trials of antibiotics for neonatal infections: a systematic review

AIMS

Antibiotics are a key resource for the management of infectious diseases in neonatology and their evaluation is particularly challenging. We reviewed medical literature to assess the characteristics and quality of randomized controlled trials on antibiotics in neonatal infections.

METHODS

We performed a systematic search of PubMed, Embase and the Cochrane Library from January 1995 to March 2010. Bibliographies of relevant articles were also hand-searched. We included all randomized controlled trials that involved neonates and evaluated the use of an antibiotic agent in the context of a neonatal infectious disease. Methodological quality was evaluated using the Jadad scale and the Cochrane Risk of Bias Tool. Two reviewers independently assessed studies for inclusion and evaluated methodological quality.

RESULTS

A total of 35 randomized controlled trials were evaluated. The majority were conducted in a single hospital institution, without funding. Median sample size was 63 (34-103) participants. The most frequently evaluated antibiotic was gentamicin. Respectively, 18 (51%) and 17 (49%) trials evaluated the therapeutic or prophylactic use of antibiotics in various neonatal infections. Overall, the methodological quality was poor and did not improve over the years. Risk of bias was high in 66% of the trials.

CONCLUSIONS

Design and reporting of randomized controlled trials of antibacterial agents in neonates should be improved. Nevertheless, the necessity of implementing such trials when antibacterial efficacy has already been established in other age groups may be questioned and different methods of evaluation should be further developed.

Population pharmacokinetic modelling of total and unbound cefazolin plasma concentrations as a guide for dosing in preterm and term neonates

OBJECTIVES

Cefazolin is frequently administered for antimicrobial prophylaxis and treatment of infections. In neonates, pharmacokinetic observations are limited and dosing regimens variable. The aim of this study was to describe the pharmacokinetics of cefazolin in neonates based on total and unbound concentrations to optimize cefazolin dosing.

METHODS

Thirty-six neonates [median birth body weight 2720 (range 540-4200) g, current body weight (cBW) 2755 (830-4200) g and postnatal age (PNA) 9 (1-30) days] receiving intravenous cefazolin (50 mg/kg/8 h) were included. Based on 119 total and unbound plasma concentrations, a population pharmacokinetic analysis with a covariate analysis was performed. Monte Carlo simulations were performed aiming for unbound concentrations above an MIC of 8 mg/L (>60% of the time) in all patients.

RESULTS

A one-compartment pharmacokinetic model was developed in which total and unbound concentrations were linked by maximum protein binding (Bmax) of 136 mg/L and a dissociation constant (KD) for cefazolin protein binding of 46.5 mg/L. cBW was identified as covariate for volume of distribution (V), bBW and PNA for clearance and albumin plasma concentration for Bmax, explaining 50%, 58% and 41% of inter-individual variability in V, clearance and Bmax, respectively. Based on Monte Carlo simulations, a body weight- and PNA-adapted dosing regimen that resulted in similar exposure across different weight and age groups was proposed.

CONCLUSIONS

A neonatal pharmacokinetic model taking into account total and unbound cefazolin concentrations with saturable plasma protein binding was identified. As cBW and PNA were the most important covariates, these may be used for individualized dosing in neonates.

Considering CYP1A2 phenotype and genotype for optimizing the dose of olanzapine in the management of schizophrenia

INTRODUCTION

Schizophrenia, a mental disorder, is a debilitating condition which typically strikes young people in their early 20's. Antipsychotic medications are widely prescribed for the treatment of schizophrenia however a balancing act is necessary to provide the correct dose to each patient. It is suggested that a large number of patients discontinue antipsychotic pharmacotherapy because the treatments provided do not always reduce the positive symptoms of the disease, while many have adverse effects on the patients. This implies that neither the incorrect drug nor the optimal dosage for that patient is achieved.

AREAS COVERED

The current review investigates variability in response to olanzapine with a specific focus on the common intrinsic and extrinsic factors that influence both olanzapine and CYP1A2 activity. Furthermore, the authors discuss the utilization of phenotyping and genotyping of CYP1A2 and their potential utility in clinical practice for olanzapine dosing regimens. The authors also consider the potential of pharmacometrics compared to pharmacogenomics as a tool to personalize medicine.

EXPERT OPINION

Careful consideration must be given to the impact of a genetic variant on the disposition of a drug prior to implementing genetic 'tests' to determine response. CYP1A2 phenotypic assessment can yield important information regarding the disposition of olanzapine; however, it relies on the accuracy of the metric and the minimal impact of other metabolic pathways. The application of pharmacometrics provides an effective method to establish covariates that significantly influence olanzapine disposition which can incorporate phenotype and/or genotype.

The management of community-acquired pneumonia in infants and children older than 3 months of age: clinical practice guidelines by the Pediatric Infectious Diseases Society and the Infectious Diseases Society of America

Evidenced-based guidelines for management of infants and children with community-acquired pneumonia (CAP) were prepared by an expert panel comprising clinicians and investigators representing community pediatrics, public health, and the pediatric specialties of critical care, emergency medicine, hospital medicine, infectious diseases, pulmonology, and surgery. These guidelines are intended for use by primary care and subspecialty providers responsible for the management of otherwise healthy infants and children with CAP in both outpatient and inpatient settings. Site-of-care management, diagnosis, antimicrobial and adjunctive surgical therapy, and prevention are discussed. Areas that warrant future investigations are also highlighted.