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Introduction: Oral ibuprofen is more effective than intravenous (IV) ibuprofen for closure of a patent ductus arteriosus (PDA). This study explored whether higher concentrations of the biologically active S-enantiomer or increased R- to S-conversion following oral dosing could explain this finding. Methods: Two datasets containing 370 S- and R-ibuprofen concentrations from 95 neonates with PDA treated with oral (n = 27, 28%) or IV ibuprofen were analyzed using nonlinear mixed effects modeling. Concentration-time profiles in typical neonates were explored and compared in different dosing or R- to S-conversion scenarios. Results: Postnatal age (PNA), gestational age (GA), and being small for GA impacted S- and R-ibuprofen clearance. Upon oral dosing, S-ibuprofen concentrations were lower compared to IV ibuprofen for a large part of the dosing interval. We could show that R- to S-conversion will not exceed 45%. Exploration of a 30% presystemic R- to S-conversion resulted in a 25–32% increase in S-ibuprofen exposure following oral administration with AUC72h values varying between 700–2,213 mg*h/L (oral) and 531–1,762 (IV) for the standard or 1,704–2,893 (oral) and 1,295–2,271 mg*h/L (IV) for PNA-based dosing. Discussion: The absence of higher S-ibuprofen concentrations does not support a beneficial concentration-time profile after oral dosing. While a fraction of up to 45% presystemic R- to S-conversion could not be ruled out, the impact of such a low conversion might be only relevant for the standard but not high dosing regimens, considering reported exposure-response targets. Perhaps, the lack of high peak concentrations observed following IV dosing may play a role in the observed effects upon oral dosing.

Dasatinib, an orally administered Src-family kinase inhibitor, is combined with the standard chemotherapeutic regimen to enhance antineoplastic activity against core-binding factor acute myeloid leukemia (CBF-AML) in adults; however, limited data are available for use in children. In the present study, we studied the pharmacokinetics and safety of dasatinib in children. Dasatinib (60 or 80 mg/m2 once daily) was administered to 20 children with CBF-AML. Blood samples were collected and drug concentrations were quantified by high-performance liquid chromatography–tandem mass spectrometry (HPLC-MS/MS). Population pharmacokinetic analysis and Monte-Carlo simulations were performed using NONMEM software, and safety analyses were assessed according to the National Cancer Institute Common Terminology Criteria for Adverse Events (NCI-CTCAE) version 4.0 (NCT03844360). Twenty pediatric patients (3.3–14.4 years of age) were included, and a total of 40 dasatinib concentrations were available for population pharmacokinetic analysis. The mean (standard deviation) of the estimated area under the concentration-time curve extrapolated to steady state (AUCss) of dasatinib 60 and 80 mg/m2 was 366.1 (146.6) ng·h/mL and 425.3 (150.7) ng·h/mL, respectively. The majority of adverse events were grade 1/2 in severity, including thrombocytopenia, rash, and pain in the extremities. The estimated cumulative incidence of complete remission and complete molecular response were 95.0% and 75.5%, respectively. The population pharmacokinetics of orally administered dasatinib were evaluated in pediatric CBF-AML patients. The AUCss of dasatinib (80 mg/m2) in CBF-AML pediatric patients was similar to those of dasatinib (100 mg) in adult patients. Dasatinib is well-tolerated in pediatric patients with CBF-AML.

In premature infants, effective and safe drug therapy depends on optimal dose selection and requires a thorough understanding of the underlying disease(s) of these fragile infants as well as the pharmacokinetics and pharmacodynamics of the drugs selected to treat their diseases. Differences in gestational and postnatal age or weight are the major determinants of the observed variability in drug disposition and effect in these infants. This article presents an outline on how to translate the results of a population pharmacokinetic/pharmacodynamic study into rational dosing regimens, and how physiologically based pharmacokinetic modeling, electronic health records, and the abundantly available data of vital functions of premature infants during their stay in the neonatal intensive care unit for evaluation of their pharmacotherapy can be used to tailor the most safe and effective dose in these infants.

ObjectiveExploration of a novel therapeutic drug monitoring (TDM) strategy to personalise use of ibuprofen for closure of patent ductus arteriosus (PDA) in preterm neonates.DesignProspective, single-centre, open-label, pharmacokinetics study in preterm neonates.SettingNeonatal intensive care unit at McMaster Children’s Hospital.PatientsNeonates with a gestational age ≤28+6 weeks treated with oral ibuprofen for closure of a PDA.MethodsPopulation pharmacokinetic parameters, concentration-time profiles and exposure metrics were obtained using pharmacometric modelling and simulation.Main outcome measureAssociation between ibuprofen plasma concentrations measured at various sampling time points on the first day of treatment and attainment of the target exposure over the first 3 days of treatment (AUC0–72h >900 mg·hour/L).ResultsTwenty-three preterm neonates (median birth weight 780 g and gestational age 25.9 weeks) were included, yielding 155 plasma ibuprofen plasma samples. Starting from 8 hours’ postdose on the first day, a strong correlation between ibuprofen concentrations and AUC0–72h was observed. At 8 hours after the first dose, an ibuprofen concentration >20.5 mg/L was associated with a 90% probability of reaching the target exposure.ConclusionWe designed a novel and practical TDM strategy and have shown that the chance of reaching the target exposure (AUC0–72h >900 mg·hour/L) can be predicted with a single sample collection on the first day of treatment. This newly acquired knowledge can be leveraged to personalise ibuprofen dosing regimens and improve the efficacy of ibuprofen use for pharmacological closure of a PDA.

Aims Population pharmacokinetics (PK) and pharmacodynamics (PD) of tranexamic acid (TXA) have not been studied to prevent postpartum hemorrhage (PPH) in pregnant women. It is unclear which TXA dose assures sufficient PPH prevention. This study investigated population PK/PD of TXA in pregnant women who underwent cesarean delivery to determine the optimal prophylactic doses of TXA for future studies. Methods We analyzed concentration (PK) and maximum lysis (PD) data from 30 pregnant women scheduled for cesarean delivery who received 5 mg/kg, 10 mg/kg, or 15 mg/kg of TXA intravenously, using population approach. Results TXA PK was best described by a two-compartment model with first-order elimination and the following parameters: clearance (between-subject variability) of 9.4 L/hr (27.7%), central volume of 10.1 L (47.4%), inter-compartmental clearance of 22.4 L/hr (66.7%), peripheral volume of 14.0 L (13.1%), and additive error of 1.4 mg/L. The relationship between TXA concentration and maximum lysis was characterized by a sigmoid Emax model with baseline lysis of 97%, maximum inhibition of 89%, IC50 of 6.0 mg/L (65.3%), hill factor of 8.5 (86.3%), and additive error of 7.3%. Simulations demonstrated that 500 mg and 650 mg of TXA maintained therapeutic targets for 30 minutes and 1 hour respectively in 90% of patients. Conclusion This is the first population PK and PD study of TXA in pregnant women undergoing cesarean delivery. Our analysis suggests that a 650 mg dose provides adequate PPH prophylaxis up to 1 hour, which is less than the currently used 1000 mg of TXA in pregnant women.

Little is understood about neonatal pharmacokinetics immediately after delivery and during the first days of life following intrauterine exposure to maternal medications. Our objective was to develop and evaluate a novel, physiologically based pharmacokinetic modeling workflow for predicting perinatal and postnatal disposition of commonly used antiretroviral drugs administered prenatally to pregnant women living with human immunodeficiency virus. Using previously published, maternal-fetal, physiologically based pharmacokinetic models for emtricitabine, dolutegravir, and raltegravir built with PK-Sim/MoBi®, placental drug transfer was predicted in late pregnancy. The total drug amount in fetal compartments at term delivery was estimated and subsequently integrated as initial conditions in different tissues of a whole-body, neonatal, physiologically based pharmacokinetic model to predict drug concentrations in the neonatal elimination phase after birth. Neonatal elimination processes were parameterized according to published data. Model performance was assessed by clinical data. Neonatal physiologically based pharmacokinetic models generally captured the initial plasma concentrations after delivery but underestimated concentrations in the terminal phase. The mean percentage error for predicted plasma concentrations was − 71.5%, − 33.8%, and 76.7% for emtricitabine, dolutegravir, and raltegravir, respectively. A sensitivity analysis suggested that the activity of organic cation transporter 2 and uridine diphosphate glucuronosyltransferase 1A1 during the first postnatal days in term newborns is ~11% and ~30% of that in adults, respectively. These findings demonstrate the general feasibility of applying physiologically based pharmacokinetic models to predict washout concentrations of transplacentally acquired drugs in newborns. These models can increase the understanding of pharmacokinetics during the first postnatal days and allow the prediction of drug exposure in this vulnerable population.

Essentials Tranexamic acid (TXA) is an antifibrinolytic drug used to reduce bleeding. Assaying plasmin generation (PG) in plasma detects clinically relevant TXA levels in vitro and ex vivo. 3.1-16.2 µg/mL TXA half-maximally inhibits PG in plasma from women undergoing cesarean delivery. PG velocity shows the strongest dose-relationship at low TXA concentrations (≤10 µg/mL). ABSTRACT: Background Tranexamic acid (TXA) is used to reduce bleeding. TXA inhibits plasmin(ogen) binding to fibrin and reduces fibrinolysis. TXA antifibrinolytic activity is typically measured by clot lysis assays; however, effects on plasmin generation (PG) are unclear due to a lack of tools to measure PG in plasma. Aims Develop an assay to measure PG kinetics in human plasma. Determine effects of TXA on PG and compare with fibrinolysis measured by rotational thromboelastometry (ROTEM). Methods We characterized effects of plasminogen, tissue plasminogen activator, fibrinogen, and α2 -antiplasmin on PG in vitro. We also studied effects of TXA on PG in plasma from 30 pregnant women administered intravenous TXA (5, 10, or 15 mg/kg) during cesarean delivery. PG was measured by calibrated fluorescence. PG parameters were compared with TXA measured by mass spectrometry and ROTEM of whole blood. Results The PG assay is specific for plasmin and sensitive to tissue plasminogen activator, fibrin(ogen), and α2 -antiplasmin. Addition of TXA to plasma in vitro dose dependently prolonged the clot lysis time and delayed and reduced PG. For all doses of TXA administered intravenously, the PG assay detected delayed time-to-peak (≤3 hours) and reduced the velocity, peak, and endogenous plasmin potential (≤24 hours) in plasma samples obtained after infusion. The PG time-to-peak, velocity, and peak correlated significantly with TXA concentration and showed less variability than the ROTEM lysis index at 30 minutes or maximum lysis. Conclusions The PG assay detects pharmacologically relevant concentrations of TXA administered in vitro and in vivo, and demonstrates TXA-mediated inhibition of PG in women undergoing cesarean delivery.

BackgroundCharacterizing the dynamics of serum creatinine concentrations (Scr) and associated creatinine clearance (CLcr) as a measure of kidney function in extremely low birth weight (≤ 1000 g; ELBW) neonates remains challenging.MethodsWe performed a retrospective study that included longitudinal Scr (enzymatic assay) data from 148 ELBW neonates up to 6 weeks after birth. Change of Scr and inter-individual variability was characterized with nonlinear mixed-effect modeling. Key covariates such as gestational age (GA), mode of delivery (MOD), and treatment with ibuprofen or inotropic agents were investigated.ResultsA total of 2814 Scr concentrations were analyzed. GA was associated with Scr at birth (higher with advancing GA), and GA and MOD showed an association with postnatal maturation of CLcr (faster clearance increase with advancing GA and after C-section). Small CLcr decrease (≤ 5%) was quantified during ibuprofen treatment. For a GA of 27 weeks, mean Scr (estimated CLcr) at birth was 0.61 mg/dl (0.23 ml/min), increasing to 0.87 mg/dl (0.27 ml/min) at day three, and decreasing to 0.36 mg/dl (0.67 ml/min) at day 42 after birth.ConclusionsWe report the first mathematical model able to characterize Scr and CLcr in ELBW neonates during the first 6 weeks of life in a quantitative manner as a function of GA, MOD, and ibuprofen treatment. This model allows the derivation of GA-adjusted reference ranges for ELBW neonates and provides a rationale for normative Scr concentrations, and as such will help clinicians to further optimize monitoring and treatment decisions in this vulnerable patient population.

Amoxicillin is used to treat various bacterial infections (eg, pneumonia, sepsis, meningitis) in infants. Despite its frequent use, there is a lack of population pharmacokinetic studies in infants, resulting in a substantial variability in dosing regimens used in clinical practice. Therefore, the objective of this study was to evaluate the population pharmacokinetics of intravenous amoxicillin in infants and suggest an optimal dosage regimen. Blood samples were collected for the determination of amoxicillin concentrations using an opportunistic sampling strategy. The amoxicillin plasma concentrations were determined using high-performance liquid chromatography. Population pharmacokinetic analysis was performed using NONMEM. A total of 62 pharmacokinetic samples from 47 infants (age range, 0.09 to 2.0 years) were available for analysis. A 2-compartment model with first-order elimination was most suitable to describe the population pharmacokinetics of amoxicillin, and covariate analysis showed that only current body weight was a significant covariate. Monte Carlo simulation demonstrated that the currently used dosage regimen (25 mg/kg twice daily) resulted in only 22.4% of infants reaching their pharmacodynamic target, using a minimum inhibitory concentration (MIC) break point of 2 mg/L, whereas a dosage regimen (60 mg/kg thrice daily), as supported by the British National Formulary for Children, resulted in 80.9% of infants achieving their pharmacodynamic target. It is recommended to change antibiotics for infections caused by Escherichia coli (MIC = 8.0 mg/L) because only 27.9% of infants reached target using 60 mg/kg thrice daily.

Background We sought to identify microRNAs (miRNAs) associated with response to anti-TNF-α or glucocorticoids in children with inflammatory bowel disease (IBD) to generate candidate pharmacodynamic and monitoring biomarkers. Methods Clinical response was assessed by Pediatric Crohn’s Disease Activity Index and Pediatric Ulcerative Colitis Activity Index. Quantitative real-time polymerase chain reaction via Taqman Low-Density Array cards were used to identify miRNAs in a discovery cohort of responders (n = 11) and nonresponders (n = 8). Seven serum miRNAs associated with clinical response to treatment, along with 4 previously identified (miR-146a, miR-146b, miR-320a, miR-486), were selected for further study. Candidates were assessed in a validation cohort of serum samples from IBD patients pre- and post-treatment and from healthy controls. Expression of miRNA was also analyzed in inflamed mucosal biopsies from IBD patients and non-IBD controls. Results Discovery cohort analysis identified 7 miRNAs associated with therapeutic response: 5 that decreased (miR-126, miR-454, miR-26b, miR-26a, let-7c) and 2 that increased (miR-636, miR-193b). In the validation cohort, 7 of 11 candidate miRNAs changed in the same direction with response to anti-TNF-α therapies, glucocorticoids, or both. In mucosal biopsies, 7 out of 11 miRNAs were significantly increased in IBD vs healthy controls. Conclusions Five candidate miRNAs associated with clinical response and mucosal inflammation in pediatric IBD patients were identified (miR-126, let-7c, miR-146a, miR-146b, and miR-320a). These miRNAs may be further developed as pharmacodynamic and response monitoring biomarkers for use in clinical care and trials., Discovery and validation cohort analyses were conducted to identify serum microRNAs associated with therapeutic response. Plausibility was refined by evaluation of expression in inflamed mucosal biopsies. Five serum pharmacodynamic and candidate monitoring biomarkers for pediatric IBD were identified.

Despite legislation incentivizing and requiring drug companies to conduct pediatric clinical trials, there still is a 9-year delay in drug approval for pediatric labeling after the initial adult drug approval. The aim of this study was to review the experience of the US Food and Drug Administration (FDA) with combined pediatric and adult trials as a means for expediting pediatric approval and labeling. Combined pediatric and adult trials submitted to the FDA from 2012 to 2018 were reviewed. Only the publicly available labels and reviews were utilized for this analysis. Combined trials were identified for 72 products, with a total of 156 combined adult and pediatric trials. The therapeutic areas with the largest number of combined trials were in pulmonology for products reviewed under the Best Pharmaceuticals for Children Act (BPCA) and/or the Pediatric Research Equity Act (PREA), and hematology reviewed under the Orphan Drug Act (ODA). All drugs that utilized combined pediatric and adult clinical trials were approved simultaneously for both the adults and that part of the pediatric population. A separate pediatric subgroup efficacy analysis was reported in 57% and 48% of products under BPCA/PREA and the ODA, respectively, with a separate safety analysis in 48% and 38% of these products. When considering both BPCA/PREA and orphan drug studies, all the combined pediatric and adult trials allowed concurrent approval and labeling for part of the pediatric population at the time of the adult approval.

Exposure-response (E-R) relationships of vamorolone, a novel dissociative steroidal anti-inflammatory drug, were investigated in clinical trials in boys with Duchenne Muscular Dystrophy (DMD). Variables were clinical outcome measures, Fridericia-corrected QT (QTcF) duration, and pharmacodynamic (PD) biomarkers. Exposure metrics were area under the plasma concentration time curve (AUC) and maximum plasma concentration (C(max)), with a sigmoid E(max) model applied. Significant improvements of clinical efficacy outcomes were observed after 24 weeks of daily dosing. The primary outcome, time to stand from supine (TTSTAND) velocity, exhibited the highest sensitivity to vamorolone, with the lowest AUC value providing 50% of maximum effect (E50=186 ng∙hr/mL), followed by time to climb 4 stairs (TTCLIMB) (E50=478 ng∙hr/mL), time to run/walk 10 meters (TTRW) (E50=1220 ng∙hr/mL), and 6-minute walk test (6MWT) (E50=1770 ng∙hr/mL). Week 2 changes of proinflammatory PD biomarkers showed exposure-dependent decreases. The E50 was 260 ng∙hr/mL for insulin-like growth factor binding protein 2 (IGFBP-2), 1200 ng∙hr/mL for matrix metalloproteinase 12 (MMP12), 1260 ng∙hr/mL for lymphotoxin α1/β2 (LTα1/β2), 1340 ng∙hr/mL for CD23, 1420 ng∙hr/mL for Interleukin-22 binding protein (IL22BP), and 1600 ng∙hr/mL for Macrophage Derived Chemokine/C-C Motif Chemokine 22 (MDC/CCL22). No relationship was found between QTcF interval changes from baseline and C(max) at week 2 or 24. This analysis showed that improvements in clinical efficacy endpoints at week 24 and PD biomarkers at week 2 were achieved at typical vamorolone exposures of 2 mg/kg daily doses with the median AUC of 6 mg/kg doses (3651 ng∙hr/mL) corresponding to approximately 95% of maximum effects for most response variables.

Since in vitro studies and a preliminary clinical report suggested the efficacy of chloroquine for COVID-19-associated pneumonia, there is increasing interest in this old antimalarial drug. In this article, we discuss the pharmacokinetics and safety of chloroquine that should be considered in light of use in SARS-CoV-2 infections. Chloroquine is well absorbed and distributes extensively resulting in a large volume of distribution with an apparent and terminal half-life of 1.6 days and 2 weeks, respectively. Chloroquine is metabolized by cytochrome P450 and renal clearance is responsible for one third of total clearance. The lack of reliable information on target concentrations or doses for COVID-19 implies that for both adults and children, doses that proved effective and safe in malaria should be considered, such as 'loading doses' in adults (30 mg/kg over 48 h) and children (70 mg/kg over 5 days), which reported good tolerability. Here, plasma concentrations were < 2.5 μmol/L, which is associated with (minor) toxicity. While the influence of renal dysfunction, critical illness, or obesity seems small, in critically ill patients, reduced absorption may be anticipated. Clinical experience has shown that chloroquine has a narrow safety margin, as three times the adult therapeutic dosage for malaria can be lethal when given as a single dose. Although infrequent, poisoning in children is extremely dangerous where one to two tablets can potentially be fatal. In conclusion, the pharmacokinetic and safety properties of chloroquine suggest that chloroquine can be used safely for an acute virus infection, under corrected QT monitoring, but also that the safety margin is small, particularly in children.

No data support the suggestion that first-trimester dydrogesterone use increases the risk of fetal abnormalities; however, two low-quality retrospective studies (one retracted by the journal) have suggested such a link. A scoping review and meta-analysis were carried out to address this discrepancy. The literature was reviewed but it was not possible to identify any evidence of a plausible mechanism for potential causality between dydrogesterone and fetal abnormalities. To investigate whether any evidence existed, a preliminary meta-analysis was undertaken of clinical studies published since 2005 on first-trimester dydrogesterone use with assessment of fetal abnormalities. A fixed effects model was used to determine pooled odds ratios with 95% confidence intervals (95% CI). From 83 articles identified, six randomized controlled trials were included. Pooled risk ratios (RR) for maternal dydrogesterone use and fetal abnormalities gave a RR approaching 1 (RR 0.96; 95% CI 0.57, 1.62), confirming previous conclusions of no causal association between fetal abnormalities and first-trimester dydrogesterone use. Physicians, scientists and journal reviewers should exercise due diligence to prevent promulgation of retracted data. We are confident in using dydrogesterone, if indicated, in the treatment of threatened or recurrent miscarriage, and believe that its favourable safety profile should extend to its appropriate use in assisted reproductive technologies.

Medication administration errors that take place in the home are common, especially when liquid preparations are used and complex medication schedules with multiple medications are involved; children with chronic conditions are disproportionately affected. Parents and other caregivers with low health literacy and/or limited English proficiency are at higher risk for making errors in administering medications to children in their care. Recommended strategies to reduce home medication errors relate to provider prescribing practices; health literacy–informed verbal counseling strategies (eg, teachback and showback) and written patient education materials (eg, pictographic information) for patients and/or caregivers across settings (inpatient, outpatient, emergency care, pharmacy); dosing-tool provision for liquid medication measurement; review of medication lists with patients and/or caregivers (medication reconciliation) that includes prescription and over-the-counter medications, as well as vitamins and supplements; leveraging the medical home; engaging adolescents and their adult caregivers; training of providers; safe disposal of medications; regulations related to medication dosing tools, labeling, packaging, and informational materials; use of electronic health records and other technologies; and research to identify novel ways to support safe home medication administration.

Background and Objective Although acetaminophen is frequently used during pregnancy, little is known about fetal acetaminophen pharmacokinetics. Acetaminophen safety evaluation has typically focused on hepatotoxicity, while other events (fetal ductal closure/constriction) are also relevant. We aimed to develop a fetal–maternal physiologically based pharmacokinetic (PBPK) model (f-m PBPK) to quantitatively predict placental acetaminophen transfer, characterize fetal acetaminophen exposure, and quantify the contributions of specific clearance pathways in the term fetus. Methods An acetaminophen pregnancy PBPK model was extended with a compartment representing the fetal liver, which included maturation of relevant enzymes. Different approaches to describe placental transfer were evaluated (ex vivo cotyledon perfusion experiments, placental transfer prediction based on Caco-2 cell permeability or physicochemical properties [MoBi®]). Predicted maternal and fetal acetaminophen profiles were compared with in vivo observations. Results Tested approaches to predict placental transfer showed comparable performance, although the ex vivo approach showed highest prediction accuracy. Acetaminophen exposure in maternal venous blood was similar to fetal venous umbilical cord blood. Prediction of fetal acetaminophen clearance indicated that the median molar dose fraction converted to acetaminophen-sulphate and N-acetyl-p-benzoquinone imine was 0.8% and 0.06%, respectively. The predicted mean acetaminophen concentration in the arterial umbilical cord blood was 3.6 mg/L. Conclusion The median dose fraction of acetaminophen converted to its metabolites in the term fetus was predicted. The various placental transfer approaches supported the development of a generic f-m PBPK model incorporating in vivo placental drug transfer. The predicted arterial umbilical cord acetaminophen concentration was far below the suggested postnatal threshold (24.47 mg/L) for ductal closure. Electronic supplementary material The online version of this article (10.1007/s40262-020-00861-7) contains supplementary material, which is available to authorized users.

Background and Objective Little is known about acetaminophen (paracetamol) pharmacokinetics during pregnancy. The aim of this study was to develop a physiologically based pharmacokinetic (PBPK) model to predict acetaminophen pharmacokinetics throughout pregnancy. Methods PBPK models for acetaminophen and its metabolites were developed in non-pregnant and pregnant women. Physiological and enzymatic changes in pregnant women expected to impact acetaminophen pharmacokinetics were considered. Models were evaluated using goodness-of-fit plots and by comparing predicted pharmacokinetic profiles with in vivo pharmacokinetic data. Predictions were performed to illustrate the average concentration at steady state (Css,avg) values, used as an indicator for efficacy, of acetaminophen achieved following administration of 1000 mg every 6 h. Furthermore, as a measurement of potential hepatotoxicity, the molar dose fraction of acetaminophen converted to N-acetyl-p-benzoquinone imine (NAPQI) was estimated. Results PBPK models successfully predicted the pharmacokinetics of acetaminophen and its metabolites in non-pregnant and pregnant women. Predictions resulted in the lowest Css,avg in the third trimester (median [interquartile range]: 4.5 [3.8–5.1] mg/L), while Css,avg was 6.7 [5.9–7.4], 5.6 [4.7–6.3], and 4.9 [4.1–5.5] mg/L in non-pregnant, first trimester, and second trimester populations, respectively. Assuming a constant raised cytochrome P450 2E1 activity throughout pregnancy, the molar dose fraction of acetaminophen converted to NAPQI was highest during the first trimester (median [interquartile range]: 11.0% [9.1–13.4%]), followed by the second (9.0% [7.5–11.0%]) and third trimester (8.2% [6.8–10.1%]), compared with non-pregnant women (7.7% [6.4–9.4%]). Conclusion Acetaminophen exposure is lower in pregnant than in non-pregnant women, and is related to pregnancy duration. Despite these findings, higher dose adjustments cannot be advised yet as it is unknown whether pregnancy affects the toxicodynamics of NAPQI. Information on glutathione abundance during pregnancy and NAPQI in vivo data are required to further refine the presented model. Electronic supplementary material The online version of this article (10.1007/s40262-019-00799-5) contains supplementary material, which is available to authorized users.

Background: Serum creatinine (Scr) in early neonatal life (first week of life) displays extensive variability; hence, a better understanding is needed to use Scr as a diagnostic biomarker for acute kidney injury (AKI). Objective: The objective of this study was to explore Scr trends and its covariates in early neonatal life. Methods: Analysis of a rich, pooled Scr dataset (enzymatic assay) of 4,509 Scr observations in 1,181 neonates in the first week of life with birth weight, gestational age (GA), and postnatal age as covariates was conducted. Descriptive data were summarized as median and range. The Spearman rank correlation test was used to examine Scr, while the Mann-Whitney U test was used to determine the differences between the different GA (≤32, 33–36, or ≥37 weeks) categories. Results: The median Scr at delivery was 55.7 (range 28.3–194.5) µmol/L, correlating with birth weight (r = 0.088) or GA (r = 0.183) for the full dataset. At birth, the median Scr was highest in term (≥37-week) neonates. In early neonatal life (median Scr values), there was a gradual increase to attain a peak Scr by day 2–3, highest and most delayed in neonates ≤32 weeks GA. This is followed by a blunted decrease when ≤32-week neonates were compared to those of 33–36 or ≥37 weeks GA. Conclusions: The Scr pattern in early neonatal life is complex, with the highest Scr at birth in full-term neonates, while those ≤32 weeks GA displayed the highest and delayed peak Scr with a subsequent blunted decrease. Knowledge of these patterns is crucial to explore the utility of Scr as an AKI biomarker.

The extensive metabolic demands of pregnancy require specific physiological and anatomical changes. These changes affect almost all organ systems, including the cardiovascular, respiratory, renal, gastrointestinal, and hematologic system. The placenta adds another layer of complexity. These changes make it challenging for clinicians to understand presenting signs and symptoms, or to interpret laboratory and radiological tests. Furthermore, these physiological alterations can affect the pharmacokinetics and pharmacodynamics of drugs. Drug safety in lactation is only supported by limited evidence. In addition, the teratogenic effects of medications are often extrapolated from animals, which further adds uncertainties. Unfortunately, pregnant women are only rarely included in clinical drug trials, while doses, regimens, and side effects are often extrapolated from studies conducted in non-pregnant populations. In this comprehensive review, we present the changes occurring in each system with its effects on the pharmacokinetic variables. Understanding these physiological changes throughout normal pregnancy helps clinicians to optimize the health of pregnant women and their fetuses. Furthermore, the information on pregnancy-related physiology is also critical to guide study design in this vulnerable 'orphan' population, and provides a framework to explore pregnancy-related pathophysiology such as pre-eclampsia. ispartof: JOURNAL OF PHARMACOKINETICS AND PHARMACODYNAMICS vol:47 issue:4 pages:271-285 ispartof: location:United States status: published

Background Well-controlled trials of analgesics in the pediatric population are scarce. Tapentadol is a strong centrally acting analgesic which has undergone a pediatric development program investigating its suitability for treating moderate to severe acute pain across the entire pediatric age range from birth to adolescence. Here, we report data from a pivotal Phase III trial performed as part of this development program. Patients and methods This randomized, double-blind, placebo-controlled, multicenter clinical trial investigated efficacy and safety/tolerability of multiple tapentadol oral solution doses (OS; target dose 1.25 mg/kg) in the treatment of postsurgical acute pain. Data for patients aged 2 to

Objective The main aim of this analysis was to characterize the pharmacokinetics (PK) of the strong analgesic tapentadol in 2-year-old to

It is broadly accepted that children of all age groups including (preterm) neonates and young infants can perceive pain and that there is an absolute need to treat their pain safely and effectively. The approved treatment options for children, particularly (preterm) neonates and young infants, are very limited with only a few medications specifically labelled for this population. This article presents the challenges of developing pain medications for children. A short overview gives information on pain in children, including pain perception, prevalence of pain and the long-term consequences of leaving pain untreated in this vulnerable population. Current pain management practices are briefly discussed. The challenges of conducting pediatric clinical trials in general and trials involving analgesic medications in particular within the regulatory framework available to develop these medications for children are presented. Emphasis is given to the operational hurdles faced in conducting a pediatric clinical trial program. Some suggestions to overcome these hurdles are provided based on our experience during the pediatric trial program for the strong analgesic tapentadol used for the treatment of moderate to severe acute pain.

Background: Female childhood cancer survivors (CCSs) carry a risk of therapy-related gonadal dysfunction. Alkylating agents (AA) are well-established risk factors, yet inter-individual variability in ovarian function is observed. Polymorphisms in CYP450 enzymes may explain this variability in AA-induced ovarian damage. We aimed to evaluate associations between previously identified genetic polymorphisms in CYP450 enzymes and AA-related ovarian function among adult CCSs. Methods: Anti-Müllerian hormone (AMH) levels served as a proxy for ovarian function in a discovery cohort of adult female CCSs, from the pan-European PanCareLIFE cohort (n = 743, age (years): median 25.8, interquartile range (IQR) 22.1–30.6). Using two additive genetic models in linear and logistic regression, nine genetic variants in three CYP450 enzymes were analyzed in relation to cyclophosphamide equivalent dose (CED) score and their impact on AMH levels. The main model evaluated the effect of the variant on AMH and the interaction model evaluated the modifying effect of the variant on the impact of CED score on log-transformed AMH levels. Results were validated, and meta-analysis performed, using the USA-based St. Jude Lifetime Cohort (n = 391, age (years): median 31.3, IQR 26.6–37.4). Results: CYP3A4*3 was significantly associated with AMH levels in the discovery and replication cohort. Meta-analysis revealed a significant main deleterious effect (Beta (95% CI): −0.706 (−1.11–−0.298), p-value = 7 × 10−4) of CYP3A4*3 (rs4986910) on log-transformed AMH levels. CYP2B6*2 (rs8192709) showed a significant protective interaction effect (Beta (95% CI): 0.527 (0.126–0.928), p-value = 0.01) on log-transformed AMH levels in CCSs receiving more than 8000 mg/m2 CED. Conclusions: Female CCSs CYP3A4*3 carriers had significantly lower AMH levels, and CYP2B6*2 may have a protective effect on AMH levels. Identification of risk-contributing variants may improve individualized counselling regarding the treatment-related risk of infertility and fertility preservation options.

Purpose: Chemotherapy induced nausea and vomiting (CINV) is a frequently seen burdensome adverse event of cancer therapy. The 5-HT3 receptor antagonist ondansetron has improved the rates of CINV but, unfortunately, up to 30% of patients do not obtain satisfactory control. This study examined whether genetic variations in a relevant drug metabolizing enzyme (CYP2D6), transporter (ABCB1) or receptor (5-HT3) were associated with ondansetron failure. Methods: DNA was extracted from blood and used to genotype: ABCB1 (3435C>T (rs1045642) and G2677A/T (rs2032582)), 5-HT3RB (rs3758987 T>C and rs45460698 (delAAG/dupAAG)) and CYP2D6 variants. Ondansetron failure was determined by review of the medical records and by patient-reported outcomes (PROs). Results: 129 patients were approached; 103 consented. Participants were less than 1 to 33 years (mean 6.85). 39.8% were female, 58.3% were White (22.3% Black, 19.4% other); and 24.3% were Hispanic. A majority had leukemia or lymphoma, and 41 (39.8%) met the definition of ondansetron failure. Of variants tested, rs45460698 independently showed a significant difference in risk of ondansetron failure between a mutant (any deletion) and normal allele (p=0.0281, OR 2.67). Age and BMI were both predictive of ondansetron failure (Age > 12 (OR 1.12, p=0.0012) and higher BMI (OR 1.13, p=0.0119)). In multivariate analysis, age > 12 was highly predictive of ondansetron failure (OR 7.108, p=0.0008). rs45460698 was predictive when combined with an increased nausea phenotype variant of rs1045642 (OR 3.45, p=0.0426). Conclusion: Select phenotypes of 5-HT3RB and ABCB1, age, and potentially BMI can help predict increased risk for CINV in a diverse pediatric oncology population.

Yi Zheng,1 Pan-Pan Ye,2 Yue Zhou,1 Su-Ying Wu,3 Xi-Ting Liu,1 Bin Du,1 Bo-Hao Tang,1 Min Kan,1 Ai-Qing Nie,1 Rui Yin,1 Meng Wang,1 Guo-Xiang Hao,1 Lin-Lin Song,2 Xin-Mei Yang,2 Xin Huang,2 Le-Qun Su,2 Wen-Qi Wang,2 John van den Anker,4– 6 Wei Zhao1,2 1Department of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, People’s Republic of China; 2Department of Clinical Pharmacy, The First Affiliated Hospital of Shandong First Medical University & Shandong Provincial Qianfoshan Hospital, Shandong Engineering and Technology Research Center for Pediatric Drug Development, Shandong Medicine and Health Key Laboratory of Clinical Pharmacy, Jinan, 250014, People’s Republic of China; 3Shandong University of Traditional Chinese Medicine, Jinan, People’s Republic of China; 4Division of Clinical Pharmacology, Children’s National Hospital, Washington, DC, USA; 5Departments of Pediatrics, Pharmacology & Physiology, Genomics & Precision Medicine, George Washington University, School of Medicine and Health Sciences, Washington, DC, USA; 6Department of Paediatric Pharmacology and Pharmacometrics, University Children’s Hospital Basel, University of Basel, Basel, SwitzerlandCorrespondence: Wei ZhaoDepartment of Clinical Pharmacy, School of Pharmaceutical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, People’s Republic of ChinaEmail zhao4wei2@hotmail.comPurpose: Inflammation has a significant impact on CYP3A activity. We hypothesized that this effect might be age dependent. Our objective was to conduct a population pharmacokinetic study of midazolam in mice at different developmental stages with varying degrees of inflammation to verify our hypothesis.Methods: Different doses (2 and 5 mg/kg) of lipopolysaccharide (LPS) were used to induce different degrees of systemic inflammation in Swiss mice (postnatal age 9– 42 days, n = 220). The CYP3A substrate midazolam was selected as the pharmacological probe to study CYP3A activity. Postnatal age, current body weight, serum amyloid A protein 1 (SAA1) levels and LPS doses were collected as covariates to perform a population pharmacokinetic analysis using NONMEM 7.2.Results: A population pharmacokinetic model of midazolam in juvenile and adult mice was established. Postnatal age and current body weight were the most significant and positive covariates for clearance and volume of distribution. LPS dosage was the most significant and negative covariate for clearance. LPS dosage can significantly reduce the clearance of midazolam by 21.8% and 38.7% with 2 mg/kg and 5 mg/kg, respectively. Moreover, the magnitude of the reduction was higher in mice with advancing postnatal age.Conclusion: Both inflammation and ontogeny have an essential role in CYP3A activity in mice. The effect of LPS-induced systemic inflammation on midazolam clearance in mice is dependent on postnatal age.Keywords: CYP3A activity, ontogeny, inflammation, pharmacokinetic, mice

Augmented renal clearance (ARC) can cause underexposure to vancomycin, thereby increasing the risk of treatment failure. Our objective was to evaluate population pharmacokinetics and optimize the dosing regimen of vancomycin in a pediatric population with ARC. Sparse pharmacokinetic sampling and therapeutic drug monitoring (TDM) data were collected from pediatric patients with ARC treated with vancomycin. A pharmacokinetic model was developed using NONMEM 7.2. The dosing regimen was optimized using Monte Carlo dose simulations. A total of 242 vancomycin serum concentrations from 113 patients (age range, 0.4 to 14.9 years; 49 females and 64 males) were available. The mean vancomycin dose was 58.8 mg/kg body weight/day (13.6 mg/kg/dose), and the mean vancomycin serum trough concentration was 6.5 mg/liter. A one-compartment pharmacokinetic model with first-order elimination was developed. Body weight and age were the most significant and positive covariates for clearance and volume of distribution. For the pediatric population with ARC, the current recommended vancomycin dose of 60 mg/kg/day was associated with a high risk of underdosing. To reach the target area under the concentration-time curve over 24 h in the steady state divided by the MIC (AUC/MIC) ratio of 400 to 700 in these pediatric patients, the vancomycin dose should be increased to 75 mg/kg/day for infants and children between 1 month and 12 years of age and 70 mg/kg/day for adolescents between 12 and 18 years of age. In conclusion, a one-compartment pharmacokinetic model with first-order elimination was established with body weight and age as significant covariates. An optimal dosing regimen was developed in pediatric patients with ARC aged 1 month to 18 years.

AIMS Early-onset sepsis (EOS) is a common disease in neonates with a high morbidity and mortality rate. Piperacillin/tazobactam has been used extensively and empirically for EOS treatment without clinically validated dosing regimens, although the population pharmacokinetics (PPK) of piperacillin in neonates has been reported. Therefore, we wanted to study the effectiveness and tolerance of a PPK model-based dosing regimen of piperacillin/tazobactam in EOS patients. METHODS A prospective, single-centre, phase II clinical study of piperacillin/tazobactam in neonates with EOS was conducted. The dosing regimen (90 mg·kg-1 , q8h) was determined based on a previous piperacillin PPK model in young infants using NONMEM v7.4. The pharmacodynamics (PD) target (70%fT > MIC, free drug concentration above MIC during 70% of the dosing interval) attainment was calculated using NONMEM combined with an opportunistic sampling design. The clinical treatment data were collected. RESULTS A total of 52 neonates were screened and 49 neonates completed their piperacillin/tazobactam treatment course and were included in this analysis. The median (range) values of postmenstrual age were 33.57 (range 26.14-41.29) weeks. Forty-seven (96%) neonates reached their PD target. Eight (16%) neonates experienced treatment failure clinically. The mean (SD, range) duration of treatment and length of hospitalization were 100.1 (62.2, 36.2-305.8) hours and 31 (30, 5-123) days. There were no obvious adverse events and no infection-related deaths occurred in the first month of life. CONCLUSIONS A model-based dosing regimen of piperacillin/tazobactam was evaluated clinically, was tolerated well and was determined to be effective for EOS treatment.

Background Fosfomycin has the potential to be re-purposed as part of a combination therapy to treat neonatal sepsis where resistance to current standard of care (SOC) is common. Limited data exist on neonatal fosfomycin pharmacokinetics and estimates of bioavailability and CSF/plasma ratio in this vulnerable population are lacking. Objectives To generate data informing the appropriate dosing of IV and oral fosfomycin in neonates using a population pharmacokinetic analysis of plasma and CSF data. Methods The NeoFosfo study (NCT03453177) was a randomized trial that examined the safety and pharmacokinetics of fosfomycin comparing SOC versus SOC plus fosfomycin. Sixty-one neonates received fosfomycin (100 mg/kg IV q12h for 48 h) and then they converted to oral therapy at the same dose. Two plasma pharmacokinetic samples were taken following the first IV and oral doses, sample times were randomized to cover the whole pharmacokinetic profile and opportunistic CSF pharmacokinetic samples were collected. A population pharmacokinetic model was developed in NONMEM and simulations were performed. Results In total, 238 plasma and 15 CSF concentrations were collected. A two-compartment disposition model, with an additional CSF compartment and first-order absorption, best described the data. Bioavailability was estimated as 0.48 (95% CI = 0.347–0.775) and the CSF/plasma ratio as 0.32 (95% CI = 0.272–0.409). Allometric weight and postmenstrual age (PMA) scaling was applied; additional covariates included postnatal age (PNA) on clearance and CSF protein on CSF/plasma ratio. Conclusions Through this analysis a population pharmacokinetic model has been developed that can be used alongside currently available pharmacodynamic targets to select a neonatal fosfomycin dose based on an infant’s PMA, PNA and weight.

The efficacy and safety of a drug is dose or exposure related, and both are used to assess the benefit-risk balance of a given drug and ultimately to decide on the specific drug license, including its dose and indication(s). Unfortunately, both efficacy and safety are much more difficult to establish in neonates, resulting in very few drugs licensed for use in this vulnerable population. This review will focus on dose-related adverse events in neonates. Besides the regulatory classification on seriousness, adverse event assessment includes aspects related to signal detection, causality, and severity. Disentangling confounders from truly dose-related adverse drug events remains a major challenge, as illustrated for drug-induced renal impairment, drug-induced liver injury, and neurodevelopmental outcome. Causality assessment, using either routine tools (Naranjo algorithm, World Health Organization's Uppsala Monitoring Center causality tool) or a Naranjo algorithm tailored to neonates, still does not sufficiently and reliably document causality in neonates. Finally, very recently, a first neonatal severity-grading tool for neonates has been developed. Following the development of advanced pharmacokinetic approaches and techniques to predict and assess drug exposure, additional efforts are needed to truly and fully assess dose adverse drug events. To further operationalize the recently developed tools on causality and severity, reference databases on a palette of biomarkers and outcome variables and their covariates are an obvious next step. These databases should subsequently be integrated in modeling efforts to truly explore safety outcome, including aspects associated with or caused by drug dose or exposure. ispartof: JOURNAL OF CLINICAL PHARMACOLOGY vol:61 issue:Suppl 1 pages:S152-S160 ispartof: location:England status: published

Serum creatinine (sCr) is a commonly measured biomarker to estimate glomerular filtration rate (GFR) and therefore widely used as a covariate in population pharmacokinetic models of renally excreted drugs. In neonates, sCr dynamically changes during the first few weeks after birth. Missing covariates are a common problem in pharmacokinetic modeling of neonates due to the limited availability of blood sampling in number and volume. The objective of this work is to develop a parsimonious population model describing time courses of sCr in neonates with the intent to be incorporated into pharmacokinetic models of various drugs where sCr values are sparse or missing. The data for model development consisted of sCr measurements in 1080 newborns with a gestational age of 24–42 weeks. The model is based on a pharmacokinetic model of sCr that involves GFR, backflow of creatinine from the renal tubules, and urinary flow. Gestational age is the only covariate explaining between-subject variability of sCr. The model adequately describes distinct features of the sCr time course such as a peak and decline to a plateau. For a neonate with a GA of 35 weeks, the typical value of sCr at birth was 0.584 mg/dL, the peak (0.794 mg/dL) occurred 2.3 days after birth, to reach a plateau of 0.255 mg/dL approximately after 24.7 days. Model simulations reveal that in neonates with a similar postnatal age, sCr decreases with increasing GA. In summary, our model is designed to be a part of full random effects pharmacokinetic models where sCr is a significant covariate.

BackgroundThe use of vasoactive agents like arginine vasopressin (AVP) and terlipressin to treat hypotension or persistent pulmonary hypertension in critically ill preterm neonates is increasing. Therefore, a systematic review of the available data on dosing, efficacy and safety of AVP and terlipressin in this patient population appears beneficial.MethodsWe will conduct a systematic review of the available evidence on the use of AVP and terlipressin for the treatment of hypotension or persistent pulmonary hypertension in preterm neonates. We will search Ovid MEDLINE, EMBASE, the Cochrane Central Register of Controlled Trials, Web of Science and Google Scholar from inception to March 2021. Two reviewers will independently screen titles and abstracts, review the full text of eligible studies, extract data, assess the risk of bias and judge the certainty of the evidence. Our primary outcome will be an (1) improvement of end-organ perfusion after initiation of AVP or terlipressin and (2) mortality prior to discharge. Our secondary outcomes will include (1) major neurosensory abnormality and (2) the occurrence of adverse events.DiscussionThe currently available evidence on the efficacy and safety of AVP and terlipressin in preterm neonates is limited. Yet, evidence on the pharmacology of these drugs and the pathophysiology of vasoplegic shock support the biological plausibility for their clinical effectiveness in this population. Therefore, we aim to address this gap concerning the use of vasopressin and terlipressin among critically ill preterm neonates.Trial registrationThis protocol has been submitted for registration to the international database of prospectively registered systematic reviews (PROSPERO, awaiting registration number).

International audience; Background Population pharmacokinetic evaluations have been widely used in neonatal pharmacokinetic studies, while machine learning has become a popular approach to solving complex problems in the current era of big data. Objective The aim of this proof-of-concept study was to evaluate whether combining population pharmacokinetic and machine learning approaches could provide a more accurate prediction of the clearance of renally eliminated drugs in individual neonates. Methods Six drugs that are primarily eliminated by the kidneys were selected (vancomycin, latamoxef, cefepime, azlocillin, ceftazidime, and amoxicillin) as 'proof of concept' compounds. Individual estimates of clearance obtained from population pharmacokinetic models were used as reference clearances, and diverse machine learning methods and nested cross-validation were adopted and evaluated against these reference clearances. The predictive performance of these combined methods was compared with the performance of two other predictive methods: a covariate-based maturation model and a postmenstrual age and body weight scaling model. Relative error was used to evaluate the different methods. Results The extra tree regressor was selected as the best-fit machine learning method. Using the combined method, more than 95% of predictions for all six drugs had a relative error of < 50% and the mean relative error was reduced by an average of 44.3% and 71.3% compared with the other two predictive methods. Conclusion A combined population pharmacokinetic and machine learning approach provided improved predictions of individual clearances of renally cleared drugs in neonates. For a new patient treated in clinical practice, individual clearance can be predicted a priori using our model code combined with demographic data. Bo-Hao Tang and Zheng Guan contributed equally to this work.

Developmental pharmacology describes the impact of maturation on drug disposition (pharmacokinetics, PK) and drug effects (pharmacodynamics, PD) throughout the paediatric age range. This paper, written by a multidisciplinary group of experts, summarizes current knowledge, and provides suggestions to pharmaceutical companies, regulatory agencies and academicians on how to incorporate the latest knowledge regarding developmental pharmacology and innovative techniques into neonatal and paediatric drug development. Biological aspects of drug absorption, distribution, metabolism and excretion throughout development are summarized. Although this area made enormous progress during the last two decades, remaining knowledge gaps were identified. Minimal risk and burden designs allow for optimally informative but minimally invasive PK sampling, while concomitant profiling of drug metabolites may provide additional insight in the unique PK behaviour in children. Furthermore, developmental PD needs to be considered during drug development, which is illustrated by disease- and/or target organ-specific examples. Identifying and testing PD targets and effects in special populations, and application of age- and/or population-specific assessment tools are discussed. Drug development plans also need to incorporate innovative techniques such as preclinical models to study therapeutic strategies, and shift from sequential enrolment of subgroups, to more rational designs. To stimulate appropriate research plans, illustrations of specific PK/PD-related as well as drug safety-related challenges during drug development are provided. The suggestions made in this joint paper of the Innovative Medicines Initiative conect4children Expert group on Developmental Pharmacology and the European Society for Developmental, Perinatal and Paediatric Pharmacology, should facilitate all those involved in drug development. ispartof: BRITISH JOURNAL OF CLINICAL PHARMACOLOGY vol:88 issue:12 pages:4965-4984 ispartof: location:England status: published