Identifying optimal dosing strategies for meropenem in the paediatric intensive care unit through modelling and simulation.

BACKGROUND: Meropenem, a ß-lactam antibiotic commonly prescribed for severe infections, poses dosing challenges in critically ill patients due to highly variable pharmacokinetics. OBJECTIVES: We sought to develop a population pharmacokinetic model of meropenem for critically ill paediatric and young adult patients. PATIENTS AND METHODS: Paediatric intensive care unit patients receiving meropenem 20-40 mg/kg every 8 h as a 30 min infusion were prospectively followed for clinical data collection and scavenged opportunistic plasma sampling. Nonlinear mixed effects modelling was conducted using Monolix®. Monte Carlo simulations were performed to provide dosing recommendations against susceptible pathogens (MIC ≤ 2 mg/L). RESULTS: Data from 48 patients, aged 1 month to 30 years, with 296 samples, were described using a two-compartment model with first-order elimination. Allometric body weight scaling accounted for body size differences. Creatinine clearance and percentage of fluid balance were identified as covariates on clearance and central volume of distribution, respectively. A maturation function for renal clearance was included. Monte Carlo simulations suggested that for a target of 40% fT > MIC, the most effective dosing regimen is 20 mg/kg every 8 h with a 3 h infusion. If higher PD targets are considered, only continuous infusion regimens ensure target attainment against susceptible pathogens, ranging from 60 mg/kg/day to 120 mg/kg/day. CONCLUSIONS: We successfully developed a population pharmacokinetic model of meropenem using real-world data from critically ill paediatric and young adult patients with an opportunistic sampling strategy and provided dosing recommendations based on the patients' renal function and fluid status.

Optimizing Piperacillin Dosing in Pediatric Liver Transplant Recipients: A Case Series.

BACKGROUND: Pathophysiological changes post-liver transplantation impact the pharmacokinetics and pharmacodynamics of antibiotics. Piperacillin, often used in combination with tazobactam, is a key antibiotic after transplantation to its broad-spectrum activity, but there is a lack of specific pharmacokinetic data in this population. This study aims to describe the pharmacokinetic parameters and target attainment of piperacillin in pediatric liver transplant recipients. METHODS: Patients with preserved renal function (estimated glomerular filtration rate > 50 mL/min/1.73 m2) receiving intravenous piperacillin-tazobactam at 112.5 mg/kg every 8 h (100 mg piperacillin/12.5 mg tazobactam), with a rapid infusion (0.5-1 h), were included. Two blood samples per child were collected during the same interval within 48 h of starting therapy. A Bayesian approach was applied to estimate individual pharmacokinetic parameters and perform dosing recommendations against Enterococcus spp., Enterobacterales and Pseudomonas aeruginosa. RESULTS: Eight patients with median age of 8 months were included. Median piperacillin clearance and central volume of distribution for the cohort were 11.11 L/h/70 kg and 9.80 L/70 kg, respectively. Seven patients (87.5%) presented with concentrations below the target of 100% fT > MIC. Simulations suggested that these patients required more frequent dosing and extended duration of infusion to ensure target attainment. One patient (12.5%) had trough concentrations that exceed 16 mg/L and could receive a lower daily dose. CONCLUSIONS: This case series highlights the importance of personalized therapy in pediatric liver transplant recipients due to the unpredictable and highly variable piperacillin pharmacokinetics in this population.

Pharmacokinetic Factors Associated With Early Meropenem Target Attainment in Pediatric Severe Sepsis.

OBJECTIVES: To determine the frequency of early meropenem concentration target attainment (TA) in critically ill children with severe sepsis; to explore clinical, therapeutic, and pharmacokinetic factors associated with TA; and to assess how fluid resuscitation and volume status relate to early TA. DESIGN: Retrospective analysis of prospective observational cohort study. SETTING: PICU in a single academic quaternary care children's hospital. PATIENTS: Twenty-nine patients starting meropenem for severe sepsis (characterized as need for positive pressure ventilation, vasopressors, or ≥ 40 mL/kg bolused fluid), of which 17 were newly escalated to PICU level care. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Concentration-time profiles were analyzed using modeling software employing opportunistic sampling, Bayesian estimation, and a population pharmacokinetic model. Time above four times minimum inhibitory concentration (T > 4×MIC), using the susceptibility breakpoint of 1 µg/mL, was determined for each patient over the first 24 hours of meropenem therapy, as well as individual clearance and volume of distribution (Vd) estimates. Twenty-one of 29 patients met a target of 40%T > MIC 4 µg/mL. Reaching TA, vs. not, was associated with lower meropenem clearance. We failed to identify a difference in Vd or an association between the TA group and age, weight, creatinine-based estimated glomerular filtration rate (eGFR), or the amount of fluid administered. eGFR was, however, negatively correlated with overall T > MIC. CONCLUSIONS: Eight of 29 pediatric patients with early severe sepsis did not meet the selected TA threshold within the first 24 hours of meropenem therapy. Higher clearance was associated with failure to meet targets. Identifying patients likely to have higher meropenem clearance could help with dosing regimens.

Relationship between piperacillin concentrations, clinical factors and piperacillin/tazobactam-associated acute kidney injury.

BACKGROUND: Piperacillin/tazobactam, a commonly used antibiotic, is associated with acute kidney injury (AKI). The relationship between piperacillin concentrations and AKI remains unknown. OBJECTIVE: Estimate piperacillin exposures in critically ill children and young adults administered piperacillin/tazobactam to identify concentrations and clinical factors associated with piperacillin-associated AKI. PATIENTS AND METHODS: We assessed piperacillin pharmacokinetics in 107 patients admitted to the paediatric ICU who received at least one dose of piperacillin/tazobactam. Piperacillin AUC, highest peak (Cmax) and highest trough (Cmin) in the first 24 hours of therapy were estimated. Piperacillin-associated AKI was defined as Kidney Disease: Improving Global Outcomes (KDIGO) Stage 2/3 AKI present >24 hours after initial piperacillin/tazobactam dose. Likelihood of piperacillin-associated AKI was rated using the Naranjo Adverse Drug Reaction Probability Scale. Multivariable logistic regression was performed to identify patient and clinical predictors of piperacillin-associated AKI. RESULTS: Out of 107 patients, 16 (15%) were rated as possibly or probably having piperacillin-associated AKI. Estimated AUC and highest Cmin in the first 24 hours were higher in patients with piperacillin-associated AKI (2042 versus 1445 mg*h/L, P = 0.03; 50.1 versus 10.7 mg/L, P < 0.001). Logistic regression showed predictors of piperacillin-associated AKI included higher Cmin (OR: 5.4, 95% CI: 1.7-23) and age (OR: 1.13, 95% CI: 1.05-1.25). CONCLUSIONS: We show a relationship between estimated piperacillin AUC and highest Cmin in the first 24 hours of piperacillin/tazobactam therapy and piperacillin-associated AKI, suggesting total piperacillin exposure early in the course is associated with AKI development. These data could serve as the foundation for implementation of model-informed precision dosing to reduce AKI incidence in patients given piperacillin/tazobactam.

Cefepime pharmacokinetics in critically ill children and young adults undergoing continuous kidney replacement therapy.

OBJECTIVES: Cefepime is an antibiotic commonly used to treat sepsis and is cleared by renal excretion. Cefepime dosing requires adjustment in patients with decreased kidney function and in those receiving continuous kidney replacement therapy (CKRT). We aimed to characterize cefepime PK in a diverse cohort of critically ill paediatric patients on CKRT. METHODS: Patients were identified from an ongoing pharmacokinetic/pharmacodynamic (PK/PD) study of beta-lactam antibiotics, and were included if they had received at least two cefepime doses in the ICU and were on CKRT for at least 24 h. PK parameters were estimated using MwPharm++ with Bayesian estimation and a paediatric population PK model. Target attainment was assessed as time of free cefepime concentrations above minimum inhibitory concentration (fT > 1× or 4 × MIC). RESULTS: Seven patients were included in the study (ages 2 to 20 years). CKRT indications included liver failure (n = 1), renal failure (n = 4) and fluid overload (n = 2). Total effluent flow rates ranged from 1833 to 3115 (mean 2603) mL/1.73 m2/h, while clearance was 2.11-3.70 (mean 3.0) L/h/70 kg. Effluent flows were lower, but clearance and fT > MIC were similar to paediatric data published previously. Using Pseudomonas aeruginosa MIC breakpoints, all patients had 100% of dosing interval above MIC, but only one had 100% of dosing interval above 4× MIC. CONCLUSIONS: Since most patients failed to attain stringent targets of 100% fT > 4×  MIC, model-informed precision dosing may benefit such patients.

Ceftriaxone Pharmacokinetics and Pharmacodynamics in 2 Pediatric Patients on Extracorporeal Membrane Oxygenation Therapy.

BACKGROUND: Critically ill patients with cardiac or respiratory failure may require extracorporeal membrane oxygenation (ECMO). Antibiotics are frequently administered when the suspected cause of organ failure is an infection. Ceftriaxone, a ß-lactam antibiotic, is commonly used in patients who are critically ill. Although studies in adults on ECMO have suggested minimal impact on ceftriaxone pharmacokinetics, limited research exists on ceftriaxone pharmacokinetics/pharmacodynamics (PK/PD) in pediatric ECMO patients. We report the PK profiles and target attainment of 2 pediatric patients on ECMO who received ceftriaxone. METHODS: Ceftriaxone concentrations were measured in 2 pediatric patients on ECMO using scavenged opportunistic sampling. PK profiles were generated and individual PK parameters were estimated using measured free ceftriaxone concentrations and a published population PK model in children who are critically ill, using Bayesian estimation. RESULTS: Patient 1, an 11-year-old boy on venovenous ECMO for respiratory failure received 2 doses of 52 mg/kg ceftriaxone 12 hours apart while on ECMO and additional doses every 12 hours off ECMO. On ECMO, ceftriaxone clearance was 13.0 L/h/70 kg compared with 7.6 L/h/70 kg off ECMO, whereas the model-predicted mean clearance in children who are critically ill without ECMO support was 6.54 L/h/70 kg. Patient 2, a 2-year-old boy on venoarterial ECMO due to cardiac arrest received 50 mg/kg ceftriaxone every 12 hours while on ECMO for >7 days. Only clearance while on ECMO could be estimated (9.1 L/h/70 kg). Trough concentrations in both patients were >1 mg/L (the breakpoint for Streptococcus pneumoniae ) while on ECMO. CONCLUSIONS: ECMO increased ceftriaxone clearance above the model-predicted clearances in the 2 pediatric patients studied. Twelve-hour dosing allowed concentrations to remain above the breakpoint for commonly targeted bacteria but not 4 times the breakpoint in one patient, suggesting that precision dosing may be beneficial to ensure target attainment in children on ECMO.

Population Pharmacokinetic Modeling of Total and Free Ceftriaxone in Critically Ill Children and Young Adults and Monte Carlo Simulations Support Twice Daily Dosing for Target Attainment.

Critical illness, including sepsis, causes significant pathophysiologic changes that alter the pharmacokinetics (PK) of antibiotics. Ceftriaxone is one of the most prescribed antibiotics in patients admitted to the pediatric intensive care unit (PICU). We sought to develop population PK models of both total ceftriaxone and free ceftriaxone in children admitted to a single-center PICU using a scavenged opportunistic sampling approach. We tested if the presence of sepsis and phase of illness (before or after 48 h of antibiotic treatment) altered ceftriaxone PK parameters. We performed Monte Carlo simulations to evaluate whether dosing regimens commonly used in PICUs in the United States (50 mg/kg of body weight every 12 h versus 24 h) resulted in adequate antimicrobial coverage. We found that a two-compartment model best described both total and free ceftriaxone concentrations. For free concentrations, the population clearance value is 6.54 L/h/70 kg, central volume is 25.4 L/70 kg, and peripheral volume is 19.6 L/70 kg. For both models, we found that allometric weight scaling, postmenstrual age, creatinine clearance, and daily highest temperature had significant effects on clearance. The presence of sepsis or phase of illness did not have a significant effect on clearance or volume of distribution. Monte Carlo simulations demonstrated that to achieve free concentrations above 1 µg/ml for 100% of the dosing intervals, a dosing regimen of 50 mg/kg every 12 h is recommended for most patients. A continuous infusion could be considered if the target is to maintain free concentrations four times above the MICs (4 µg/ml).

Perspectives from the Society for Pediatric Research: pharmacogenetics for pediatricians.

This review evaluates the pediatric evidence for pharmacogenetic associations for drugs that are commonly prescribed by or encountered by pediatric clinicians across multiple subspecialties, organized from most to least pediatric evidence. We begin with the pharmacogenetic research that led to the warning of increased risk of death in certain pediatric populations ("ultrarapid metabolizers") who are prescribed codeine after tonsillectomy or adenoidectomy. We review the evidence for genetic testing for thiopurine metabolism, which has become routine in multiple pediatric subspecialties. We discuss the pharmacogenetic research in proton pump inhibitors, for which clinical guidelines have recently been made available. With an increase in the prevalence of behavioral health disorders including attention deficit hyperactivity disorder (ADHD), we review the pharmacogenetic literature on selective serotonin reuptake inhibitors, selective norepinephrine reuptake inhibitors, and ADHD medications. We will conclude this section on the current pharmacogenetic data on ondansetron. We also provide our perspective on how to integrate the current research on pharmacogenetics into clinical care and what further research is needed. We discuss how institutions are managing pharmacogenetic test results and implementing them clinically, and how the electronic health record can be leveraged to ensure testing results are available and taken into consideration when prescribing medications. IMPACT: While many reviews of pharmacogenetics literature are available, there are few focused on pediatrics. Pediatricians across subspecialties will become more comfortable with pharmacogenetics terminology, know resources they can use to help inform their prescribing habits for drugs with known pharmacogenetic associations, and understand the limitations of testing and where further research is needed.

Precision dosing of vancomycin: in defence of AUC-guided therapy in children.

In 2020, new vancomycin guidelines were released, recommending the transition from trough-based to AUC24 monitoring for adult and paediatric patients. Given the resources required to achieve this transition, there has been debate about the costs and benefits of AUC24-based monitoring. A recent narrative review of vancomycin therapeutic drug monitoring in paediatrics claims to have uncovered the methodological weaknesses of the data that informed the guidelines and advises against premature adoption of AUC24-guided monitoring. In this article, we present supporting arguments for AUC24-guided monitoring in children, which include that: (i) troughs alone are inadequate surrogates for AUC24; (ii) vancomycin-associated nephrotoxicity has significant consequences that warrant optimization of dosing; (iii) a substantial portion of children receiving vancomycin are at high risk for poor outcomes and deserve targeted monitoring; and (iv) limited efficacy data in support of AUC24 is not a justification to revert to a less supported monitoring approach.

Piperacillin pharmacokinetics and pharmacodynamics in paediatric patients who received high frequency intra-operative piperacillin/tazobactam dosing.

Piperacillin/tazobactam (PTZ) is a broad-spectrum antibiotic, typically dosed every six hours (q6h). Guidelines recommend dosing PTZ every 2 hours (q2h) intra-operatively for complex abdominal surgery, including liver transplant. The data supporting the guidelines for intra-operative dosing are sparse and the pharmacokinetics/pharmacodynamics (PK/PD) of q2h dosing has not been studied by simulation or in humans. In this study, PK/PD parameters of high-frequency intra-operative dosing and q6h post-operative dosing were compared in critically ill children. Paediatric patients who received PTZ during complex abdominal surgery or transplant and who had intra-operative and post-operative opportunistic samples were included. Using a published PK model and observed concentrations, individual piperacillin PK/PD parameters were estimated using Bayesian estimation. Alternative post-operative dosing strategies were simulated using the patients with the highest and lowest estimated piperacillin clearance. Thirteen patients were included (median age: 3.1 years, 85% liver transplant recipients). PK parameters in the intra-operative and post-operative phases were not significantly different (clearance: 15.8 ± 7.2 vs. 12.6 ± 6.3 L/h/70 kg, P=0.070; central volume: 13.4 [13.1, 13.8] vs. 15.2 [12.2, 16.0] L/70 kg, P=0.22). At an individual level, intra-operative clearance values were -35% to 139% of the post-operative values, whereas central volume intra-operative values were -40% to 77% of the post-operative values. Intra-operative piperacillin exposure was higher during high-frequency dosing compared with the post-operative period (AUC/h: 109 [93.4, 127] vs. 62.8 [41.6, 78.3] mg/L, P=0.002). Simulations showed great variation in optimal dosing strategies that would minimise toxicity and maximise efficacy, indicating a role for individualised dosing in paediatric surgical populations.

Monte Carlo simulations of cefepime in children receiving continuous kidney replacement therapy support continuous infusions for target attainment.

BACKGROUND: Sepsis is a leading cause of acute kidney injury requiring continuous kidney replacement therapy (CKRT) and CKRT can alter drug pharmacokinetics (PK). Cefepime is used commonly in critically ill children and is cleared by CKRT, yet data regarding cefepime PK and pharmacodynamic (PD) target attainment in children receiving CKRT are scarce, so we performed Monte Carlo simulations (MCS) of cefepime dosing strategies in children receiving CKRT. METHODS: We developed a CKRT "module" in the precision dosing software Edsim++. The module was added into a pediatric cefepime PK model. 1000-fold MCS were performed using six dosing strategies in patients aged 2-25 years and ≥ 10 kg with differing residual kidney function (estimated glomerular filtration rate of 5 vs 30 mL/min/1.73 m2), CKRT prescriptions, (standard-dose total effluent flow of 2500 mL/h/1.73 m2 vs high-dose of 8000 mL/h/1.73 m2), and fluid accumulation (0-30%). Probability of target attainment (PTA) was defined by percentage of patients with free concentrations exceeding bacterial minimum inhibitory concentration (MIC) for 100% of the dosing interval (100% fT > 1xMIC) and 4xMIC using an MIC of 8 mg/L for Pseudomonas aeruginosa. RESULTS: Assuming standard-dose dialysis and minimal kidney function, > 90% PTA was achieved for 100% fT > 1x MIC with continuous infusions (CI) of 100-150 mg/kg/day (max 4/6 g) and 4-h infusions of 50 mg/kg (max 2 g), but > 90% PTA for 100% fT > 4x MIC was only achieved by 150 mg/kg CI. Decreased PTA was seen with less frequent dosing, shorter infusions, higher-dose CKRT, and higher residual kidney function. CONCLUSIONS: Our new CKRT-module was successfully added to an existing cefepime PK model for MCS in young patients on CKRT. When targeting 100% fT > 4xMIC or using higher-dose CKRT, CI would allow for higher PTA than intermittent dosing.

Major Drug-Drug Interaction Exposure Among Medicaid-Insured Children in the Outpatient Setting.

BACKGROUND AND OBJECTIVES: Drug-drug interactions (DDIs) can cause adverse drug events, but little is known about DDI exposure in children in the outpatient setting. This study aimed to determine the prevalence of major DDI exposure and factors associated with higher DDI exposure rates among children in an outpatient setting. METHODS: We performed a cross-sectional study of children aged 0 to 18 years with ≥1 ambulatory encounter, and ≥2 dispensed outpatient prescriptions study using the 2019 Marketscan Medicaid database. DDIs (exposure to a major DDI for ≥1 day) and the adverse physiologic effects of each DDI were identified using DrugBank's interaction database. Primary outcomes included the prevalence and rate of major DDI exposure. We used logistic regression to assess patient characteristics associated with DDI exposure. We examined the rate of DDI exposures per 100 children by adverse physiologic effects category, and organ-level effects (eg, heart rate-corrected QT interval prolongation). RESULTS: Of 781 019 children with ≥2 medication exposures, 21.4% experienced ≥1 major DDI exposure. The odds of DDI exposure increased with age and with medical and mental health complexity. Frequently implicated drugs included: Clonidine, psychiatric medications, and asthma medications. The highest adverse physiologic effect exposure rate per 100 children included: Increased drug concentrations (14.6), central nervous system depression (13.6), and heart rate-corrected QT interval prolongation (9.9). CONCLUSIONS: One in 5 Medicaid-insured children with ≥2 prescription medications were exposed to major DDIs annually, with higher exposures in those with medical or mental health complexity. DDI exposure places children at risk for negative health outcomes and adverse drug events, especially in the harder-to-monitor outpatient setting.

Opportunities for Pharmacogenetic Testing to Guide Dosing of Medications in Youths With Medicaid.

Importance: There are an increasing number of medications with a high level of evidence for pharmacogenetic-guided dosing (PGx drugs). Knowledge of the prevalence of dispensings of PGx drugs and their associated genes may allow hospitals and clinical laboratories to determine which pharmacogenetic tests to implement. Objectives: To investigate the prevalence of outpatient dispensings of PGx drugs among Medicaid-insured youths, determine genes most frequently associated with PGx drug dispenses, and describe characteristics of youths who were dispensed at least 1 PGx drug. Design, Setting, and Participants: This serial cross-sectional study includes data from 2011 to 2019 among youths aged 0 to 17 years in the Marketscan Medicaid database. Data were analyzed from August to December 2022. Main Outcomes and Measures: PGx drugs were defined as any medication with level A evidence as determined by the Clinical Pharmacogenetics Implementation Consortium (CPIC). The number of unique youths dispensed each PGx drug in each year was determined. PGx drugs were grouped by their associated genes for which there was CPIC level A evidence to guide dosing, and a dispensing rate (No. of PGx drugs/100 000 youths) was determined for each group for the year 2019. Demographics were compared between youths dispensed at least 1 PGx drug and those not dispensed any PGx drugs. Results: The number of Medicaid-insured youths queried ranged by year from 2 078 683 youths in 2011 to 4 641 494 youths in 2017, including 4 126 349 youths (median [IQR] age, 9 [5-13] years; 2 129 926 males [51.6%]) in 2019. The proportion of Medicaid-insured youths dispensed PGx drugs increased from 289 709 youths (13.9%; 95% CI, 13.8%-14.0%) in 2011 to 740 072 youths (17.9%; 95% CI, 17.9%-18.0%) in 2019. Genes associated with the most frequently dispensed medications were CYP2C9, CYP2D6, and CYP2C19 (9197.0 drugs [95% CI, 9167.7-9226.3 drugs], 8731.5 drugs [95% CI, 8702.5-8759.5 drugs], and 3426.8 drugs [95% CI, 3408.1-3443.9 drugs] per 100 000 youths, respectively). There was a higher percentage of youths with at least 1 chronic medical condition among youths dispensed at least 1 PGx drug (510 445 youths [69.0%; 95% CI, 68.8%-69.1%]) than among 3 386 277 youths dispensed no PGx drug (1 381 544 youths [40.8%; 95% CI, 40.7%-40.9%) (P < .001) in 2019. Conclusions and Relevance: In this study, there was an increasing prevalence of dispensings for PGx drugs. This finding suggests that pharmacogenetic testing of specific drug-gene pairs should be considered for frequently prescribed PGx drugs and their implicated genes.

Current Practices in Pharmacogenomics.

Pharmacogenomics, where genomic information is used to tailor medication management, is a strategy to maximize drug efficacy and minimize toxicity. Although pediatric evidence is less robust than for adults, medications influenced by pharmacogenomics are prescribed to children and adolescents. Evidence-based guidelines and drug label annotations are available from the Clinical Pharmacogenetics Implementation Consortium (CPIC) and the Pharmacogenomics Knowledgebase (PharmGKB). Some pediatric health care facilities use pharmacogenomics to provide dosing recommendations to pediatricians. Herein, we use a case-based approach to illustrate the use of pharmacogenomic data in pediatric clinical care and provide resources for finding and using pharmacogenomic guidelines.

Pharmacokinetic parameters over time during sepsis and the association of target attainment and outcomes in critically ill children and young adults receiving ceftriaxone.

INTRODUCTION: Early sepsis results in pharmacokinetic (PK) changes due to physiologic alterations. PK changes can lead to suboptimal drug target attainment, risking inadequate coverage from antibiotics like ceftriaxone. Little is known about how ceftriaxone PK and target attainment quantitatively change over time in patients with sepsis or the association between target attainment and outcomes in critically ill children and young adults. METHODS: A retrospective analysis of a prospective study was conducted in a single-center pediatric intensive care unit. Septic patients given at least one ceftriaxone dose (commonly as 50 mg/kg every 12 h) and who had blood obtained in both the first 48 h of therapy (early) and afterwards (late) were included. Normalized clearance and central volume were estimated and compared in both sepsis phases. We evaluated target attainment, defined as concentrations above 1× or 4× the minimum inhibitory concentration (MIC) for 100% of dosing intervals, and investigated the association between target attainment and clinical outcomes. RESULTS: Fifty-five septic patients (median age: 7.5 years) were included. Normalized clearance and central volume were similar in both phases (6.18 ± 1.48 L/h/70 kg early vs. 6.10 ± 1.61 L/h/70 kg late, p = 0.60; 26.6 [IQR 22.3, 31.3] L/70 kg early vs. 24.5 [IQR 22.0, 29.4] L/70 kg late, p = 0.18). Individual percent differences in normalized clearance and central volume between sepsis phases ranged from -39% to 276% and -51% to 212% (reference, late sepsis), respectively. Fewer patients attained the 1× MIC target in late sepsis (82% late vs. 96% early, p = 0.013), which was associated with transition to once daily dosing, typically done due to transfer from the pediatric intensive care unit (PICU) to a lower acuity unit. Failure to attain either target in late sepsis was associated with antibiotic broadening. CONCLUSION: Ceftriaxone PK parameters were similar between early and late sepsis, but there were large individual differences. Fewer patients attained MIC targets in late sepsis and all who did not attain the less stringent target received once daily dosing during this period. The failure to attain targets in late sepsis was associated with antibiotic broadening and could be an area for antibiotic stewardship intervention.

Implementation of CYP2D6-guided opioid therapy at Cincinnati Children's Hospital Medical Center.

PURPOSE: We describe the implementation of CYP2D6-focused pharmacogenetic testing to guide opioid prescribing in a quaternary care, nonprofit pediatric academic medical center. SUMMARY: Children are often prescribed oral opioids after surgeries, for cancer pain, and occasionally for chronic pain. In 2004, Cincinnati Children's Hospital Medical Center implemented pharmacogenetic testing for CYP2D6 metabolism phenotype to inform codeine prescribing. The test and reports were updated to align with changes over time in the testing platform, the interpretation of genotype to phenotype, the electronic health record, and Food and Drug Administration (FDA) guidance. The use of the test increased when a research project required testing and decreased as prescribing of oxycodone increased due to FDA warnings about codeine. Education about the opioid-focused pharmacogenetic test was provided to prescribers (eg, the pain and sickle cell teams) as well as patients and families. Education and electronic health record capability increased provider compliance with genotype-guided postsurgical prescribing of oxycodone, although there was a perceived lack of utility for oxycodone prescribing. CONCLUSION: The implementation of pharmacogenetic testing to inform opioid prescribing for children has evolved with accumulating evidence and guidelines, requiring changes in reporting of results and recommendations.