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Frymoyer A, Schwenk HT, Zorn Y, Bio L, Moss JD, Chasmawala B, Faulkenberry J, Goswami S, Keizer RJ, Ghaskari S. Model-Informed Precision Dosing of Vancomycin in Hospitalized Children: Implementation and Adoption at an Academic Children's Hospital. Front Pharmacol 2020; 11:551. [PMID: 32411000 PMCID: PMC7201037 DOI: 10.3389/fphar.2020.00551] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Accepted: 04/09/2020] [Indexed: 02/03/2023] Open
Abstract
Background Model-informed precision dosing (MIPD) can serve as a powerful tool during therapeutic drug monitoring (TDM) to help individualize dosing in populations with large pharmacokinetic variation. Yet, adoption of MIPD in the clinical setting has been limited. Overcoming technologic hurdles that allow access to MIPD at the point-of-care and placing it in the hands of clinical specialists focused on medication dosing may encourage adoption. Objective To describe the hospital implementation and usage of a MIPD clinical decision support (CDS) tool for vancomycin in a pediatric population. Methods Within an academic children’s hospital, MIPD for vancomycin was implemented via a commercial cloud-based CDS tool that utilized Bayesian forecasting. Clinical pharmacists were recognized as local champions to facilitate adoption of the tool and operated as end-users. Integration within the electronic health record (EHR) and automatic transmission of patient data to the tool were identified as important requirements. A web-link icon was developed within the EHR which when clicked sends users and needed patient-level clinical data to the CDS platform. Individualized pharmacokinetic predictions and exposure metrics for vancomycin are then presented in the form of a web-based dashboard. Use of the CDS tool as part of TDM was tracked and users were surveyed on their experience. Results After a successful pilot phase in the neonatal intensive care unit, implementation of MIPD was expanded to the pediatric intensive care unit, followed by availability to the entire hospital. During the first 2+ years since implementation, a total of 853 patient-courses (n = 96 neonates, n = 757 children) and 2,148 TDM levels were evaluated using the CDS tool. For the most recent 6 months, the CDS tool was utilized to support 79% (181/230) of patient-courses in which TDM was performed. Of 26 users surveyed, > 96% agreed or strongly agreed that automatic transmission of patient data to the tool was a feature that helped them complete tasks more efficiently; 81% agreed or strongly agreed that they were satisfied with the CDS tool. Conclusions Integration of a vancomycin CDS tool within the EHR, along with leveraging the expertise of clinical pharmacists, allowed for successful adoption of MIPD in clinical care.
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Damian MA, Hammer GB, Elkomy MH, Frymoyer A, Drover DR, Su F. Pharmacokinetics of Dexmedetomidine in Infants and Children After Orthotopic Liver Transplantation. Anesth Analg 2020; 130:209-216. [PMID: 30198929 DOI: 10.1213/ane.0000000000003761] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
BACKGROUND Dexmedetomidine (DEX) is a sedative and analgesic medication that is frequently used postoperatively in children after liver transplantation. Hepatic dysfunction, including alterations in drug clearance, is common immediately after liver transplantation. However, the pharmacokinetics (PK) of DEX in this population is unknown. The objective of this study was to determine the PK profile of DEX in children after liver transplantation. METHODS This was a single-center, open-label PK study of DEX administered as an intravenous loading dose of 0.5 μg/kg followed by a continuous infusion of 0.5 μg/kg/h. Twenty subjects, 1 month to 18 years of age, who were admitted to the pediatric intensive care unit after liver transplantation were enrolled. Whole blood was collected and analyzed for DEX concentration using a dried blood spot method. Nonlinear mixed-effects modeling was used to characterize the population PK of DEX. RESULTS DEX PK was best described by a 2-compartment model with first-order elimination. A typical child after liver transplantation with an international normalized ratio (INR) of 1.8 was found to have a whole blood DEX clearance of 52 L/h (95% confidence interval [CI], 31-73 L/h). In addition, intercompartmental clearance was 246 L/h (95% CI, 139-391 L/h), central volume of distribution was 186 L/70 kg (95% CI, 140-301 L/70 kg), and peripheral volume of distribution was 203 L (95% CI, 123-338 L). Interindividual variability ranged from 11% to 111% for all parameters. Clearance was not found to be associated with weight but was found to be inversely proportional to INR. An increase in INR to 3.2 resulted in a 50% decrease in DEX clearance. Weight was linearly correlated with central volume of distribution. All other covariates, including age, ischemic time, total bilirubin, and alanine aminotransferase, were not found to be significant predictors of DEX disposition. CONCLUSIONS Children who received DEX after liver transplantation have large variability in clearance, which was not found to be associated with weight but is influenced by underlying liver function, as reflected by INR. In this population, titration of DEX dosing to clinical effect may be important because weight-based dosing is poorly associated with blood concentrations. More attention to quality of DEX sedation may be warranted when INR values are changing.
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Berardi A, Bedetti L, Spada C, Lucaccioni L, Frymoyer A. Serial clinical observation for management of newborns at risk of early-onset sepsis. Curr Opin Pediatr 2020; 32:245-251. [PMID: 31851052 DOI: 10.1097/mop.0000000000000864] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Current management approaches for asymptomatic neonates at risk of early onset sepsis remain controversial. Strategies based entirely on clinical observation (SCO, serial clinical observation) have gained consensus. RECENT FINDINGS We briefly compare different strategies for managing asymptomatic newborns suggested in four high-income countries. Then this review details the existing differences in carrying out the SCO in the United Kingdom, the USA, and Italy; the experiences from the studies performed using the SCO; and open questions regarding this strategy. Advantages and limitations of SCO are also discussed. There is a need to assess which symptoms at birth are more predictive of early onset sepsis and therefore require immediate interventions versus those symptoms that can be monitored and re-evaluated. SUMMARY SCO strategy may require changes in the processes of newborn care at birthing centers. Nonetheless, SCO is safe and is associated with fewer laboratory evaluations and unnecessary antibiotics. Thoughtful and thorough practices related to the care of all newborns will benefit any birthing centre. VIDEO ABSTRACT: http://links.lww.com/MOP/A40.
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Wojcicki AV, Kadapakkam M, Frymoyer A, Lacayo N, Chae HD, Sakamoto KM. Repurposing Drugs for Acute Myeloid Leukemia: A Worthy Cause or a Futile Pursuit? Cancers (Basel) 2020; 12:cancers12020441. [PMID: 32069925 PMCID: PMC7072462 DOI: 10.3390/cancers12020441] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 02/05/2020] [Accepted: 02/10/2020] [Indexed: 12/20/2022] Open
Abstract
Acute myeloid leukemia (AML) is a clinically and genetically heterogenous malignancy of myeloid progenitor cells that affects patients of all ages. Despite decades of research and improvement in overall outcomes, standard therapy remains ineffective for certain subtypes of AML. Current treatment is intensive and leads to a number of secondary effects with varying results by patient population. Due to the high cost of discovery and an unmet need for new targeted therapies that are well tolerated, alternative drug development strategies have become increasingly attractive. Repurposing existing drugs is one approach to identify new therapies with fewer financial and regulatory hurdles. In this review, we provide an overview of previously U.S. Food and Drug Administration (FDA) approved non-chemotherapy drugs under investigation for the treatment of AML.
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Frymoyer A, Stockmann C, Hersh AL, Goswami S, Keizer RJ. Individualized Empiric Vancomycin Dosing in Neonates Using a Model-Based Approach. J Pediatric Infect Dis Soc 2019; 8:97-104. [PMID: 29294072 DOI: 10.1093/jpids/pix109] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2017] [Accepted: 12/11/2017] [Indexed: 01/22/2023]
Abstract
BACKGROUND Vancomycin dosing in neonates is challenging because of the large variation in pharmacokinetics. Existing empiric dosing recommendations use table-based formats, within which a neonate is categorized on the basis of underlying characteristics. The ability to individualize dosing is limited because of the small number of "dose categories," and achieving narrow exposure targets is difficult. Our objective was to evaluate a model-based dosing approach (which we designated Neo-Vanco) designed to individualize empiric vancomycin dosing in neonates. METHODS Neo-Vanco was developed on the basis of a published, externally validated population pharmacokinetic model. Using a simulation-based methodology, individualized empiric doses that maximize the probability of attaining a 24-hour area under the curve/minimum inhibitory concentration ratio (AUC24/MIC) of >400 while minimizing troughs >20 mg/L are calculated. To evaluate the Neo-Vanco strategy, retrospective data from neonates treated with vancomycin at 2 healthcare systems were used, and empiric dose recommendations from the following 4 sources were examined: Neo-Vanco, Neofax, Red Book, and Lexicomp. Predicted AUC24 and troughs were calculated and compared. RESULTS Overall, 492 neonates were evaluated (median postmenstrual age, 36 weeks [5th-95th percentiles (90% range), 25-47 weeks]; median weight, 2.4 kg [90% range, 0.6-4.8 kg]). The percentage of neonates predicted to achieve an AUC24/MIC of >400 was 94% with Neo-Vanco, 18% with Neofax, 23% with Red Book, and 55% with Lexicomp (all P < .0001 vs Neo-Vanco). Predicted troughs of >20 mg/L were infrequent and similar across the dosing approaches (Neo-Vanco, 2.8%; Neofax, 1.0% [P = .03]; Red Book, 2.6% [P = .99]; and Lexicomp, 4.1% [P = .27]. CONCLUSION A model-based dosing approach that individualizes empiric vancomycin dosing was predicted to improve achievement of target exposure levels in neonates. Prospective clinical evaluation is warranted.
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Joshi NS, Gupta A, Allan JM, Cohen RS, Aby JL, Kim JL, Benitz WE, Frymoyer A. Management of Chorioamnionitis-Exposed Infants in the Newborn Nursery Using a Clinical Examination-Based Approach. Hosp Pediatr 2019; 9:227-233. [PMID: 30833294 DOI: 10.1542/hpeds.2018-0201] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
BACKGROUND Antibiotic use in well-appearing late preterm and term chorioamnionitis-exposed (CE) infants was reduced by 88% after the adoption of a care approach that was focused on clinical monitoring in the intensive care nursery to determine the need for antibiotics. However, this approach continued to separate mothers and infants. We aimed to reduce maternal-infant separation while continuing to use a clinical examination-based approach to identify early-onset sepsis (EOS) in CE infants. METHODS Within a quality improvement framework, well-appearing CE infants ≥35 weeks' gestation were monitored clinically while in couplet care in the postpartum unit without laboratory testing or empirical antibiotics. Clinical monitoring included physician examination at birth and nurse examinations every 30 minutes for 2 hours and then every 4 hours until 24 hours of life. Infants who developed clinical signs of illness were further evaluated and/or treated with antibiotics. Antibiotic use, laboratory testing, and clinical outcomes were collected. RESULTS Among 319 initially well-appearing CE infants, 15 (4.7%) received antibiotics, 23 (7.2%) underwent laboratory testing, and 295 (92.5%) remained with their mothers in couplet care throughout the birth hospitalization. One infant had group B Streptococcus EOS identified and treated at 24 hours of age based on new-onset tachypnea and had an uncomplicated course. CONCLUSIONS Management of well-appearing CE infants by using a clinical examination-based approach during couplet care in the postpartum unit maintained low rates of laboratory testing and antibiotic use and markedly reduced mother-infant separation without adverse events. A framework for repeated clinical assessments is an essential component of identifying infants with EOS.
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Stockmann C, Olson J, Rashid J, Lubsch L, Young DC, Hersh AL, Frymoyer A, Ampofo K, Liu X, Wang Y, Sherwin CMT, Zobell JT. An Evaluation of Vancomycin Area Under the Curve Estimation Methods for Children Treated for Acute Pulmonary Exacerbations of Cystic Fibrosis Due to Methicillin-Resistant Staphylococcus aureus. J Clin Pharmacol 2018; 59:198-205. [PMID: 30371946 DOI: 10.1002/jcph.1323] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 09/14/2018] [Indexed: 11/12/2022]
Abstract
The prevalence of pulmonary methicillin-resistant Staphylococcus aureus infections in patients with cystic fibrosis (CF) has increased over the last 2 decades. Two concentrations-a postdistributive and a trough-are currently used to estimate the area under the curve (AUC) of vancomycin, an antibiotic routinely used to treat these infections, to achieve the target AUC/minimum inhibitory concentration of ≥400 mg·h/L in ensuring optimal dosing of this drug. This study evaluated precision and bias in estimating vancomycin AUCs obtained either from a population pharmacokinetic (PK) model by using a single trough concentration or from standard PK equation-based 2-point monitoring approach. AUCs were either obtained from a single trough concentration-fitted model or derived from a model fitted by 2 concentration points. Children ≥2 years of age with CF received intravenous vancomycin at 2 centers from June 2012 to December 2014. A population PK model was developed in Pmetrics to quantify the between-subject variability in vancomycin PK parameters, define the sources of PK variability, and leverage information from the population to improve individual AUC estimates. Twenty-three children with CF received 27 courses of vancomycin. The median age was 12.3 (interquartile range [IQR] 8.5-16.6) years. From the individual vancomycin PK parameter estimates from the population PK model, median AUC was 622 (IQR 529-680) mg·h/L. Values were not significantly different from the AUC calculated using the standard PK equation-based approach (median 616 [IQR 540-663] mg·h/L) (P = .89). A standard PK equation-based approach using 2 concentrations and a population PK model-based approach using a single trough concentration yielded unbiased and precise AUC estimates. Findings suggest that options exist to implement AUC-based pediatric vancomycin dosing in patients with CF. The findings of this study reveal that several excellent options exist for centers to implement AUC-based pediatric vancomycin dosing for patients with CF.
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Keizer RJ, Ter Heine R, Frymoyer A, Lesko LJ, Mangat R, Goswami S. Model-Informed Precision Dosing at the Bedside: Scientific Challenges and Opportunities. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2018; 7:785-787. [PMID: 30255663 PMCID: PMC6310898 DOI: 10.1002/psp4.12353] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Accepted: 09/11/2018] [Indexed: 01/31/2023]
Abstract
The development of model-informed precision dosing (MIPD) tools, especially in the form of native or web-based applications to be used at the bedside, has garnered marked attention in recent years. Their potential clinical benefit can be large, but it should be ensured that such tools make optimal use of available clinical data and have adequate predictive ability. Unique scientific challenges specific to MIPD remain, which may require adaptation of commonly used diagnostics in pharmacometrics.
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Chock VY, Frymoyer A, Yeh CG, Van Meurs KP. Renal Saturation and Acute Kidney Injury in Neonates with Hypoxic Ischemic Encephalopathy Undergoing Therapeutic Hypothermia. J Pediatr 2018; 200:232-239.e1. [PMID: 29866591 DOI: 10.1016/j.jpeds.2018.04.076] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2018] [Revised: 04/05/2018] [Accepted: 04/26/2018] [Indexed: 01/17/2023]
Abstract
OBJECTIVE To investigate the range of renal near-infrared spectroscopy (NIRS) measures in neonates undergoing therapeutic hypothermia for hypoxic ischemic encephalopathy (HIE) and to determine the association between renal NIRS measures and the development of acute kidney injury (AKI). STUDY DESIGN A retrospective chart review was conducted of neonates with moderate to severe HIE who received therapeutic hypothermia at a tertiary care center from 2014 to 2016. Neonates had routine continuous NIRS monitoring of cerebral and renal saturation (Rsat) as part of their clinical care for 72 hours of cooling and until 24 hours after rewarming. The outcome of AKI was defined by an abnormal rate of decline of serum creatinine over the first 5 days of life. Mixed effects models determined the association between renal NIRS measures and AKI over time. RESULTS Of 38 neonates with HIE undergoing cooling, 15 (39%) developed AKI. Rsat was lower than cerebral saturation during cooling (P < .01), but Rsat increased over time after rewarming, while renal oxygen extraction levels decreased (P < .0001). Neonates with AKI had higher Rsat levels (P < .01) compared with those without AKI after 24 hours of life. Using receiver operating characteristic curves, Rsat >75% by 24-48 hours predicted AKI with a sensitivity of 79% and specificity of 82% (area under the receiver operating characteristic curve = 0.76). CONCLUSIONS Throughout cooling, neonates with AKI had higher Rsat measures than those without AKI. These differences may reflect lower oxygen extraction by the injured kidney. NIRS monitoring of Rsat may identify neonates with HIE at risk of developing AKI.
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Das M, Padda SK, Frymoyer A, Molina J, Adjei A, Lensing JL, Miles D, Sikic BI, Wakelee HA. A safety, tolerability, and pharmacokinetic analysis of two phase I studies of multitargeted small molecule tyrosine kinase inhibitor XL647 with an intermittent and continuous dosing schedule in patients with advanced solid malignancies. Cancer Chemother Pharmacol 2018; 82:541-550. [DOI: 10.1007/s00280-018-3646-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 07/16/2018] [Indexed: 12/17/2022]
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Joshi NS, Gupta A, Allan JM, Cohen RS, Aby JL, Weldon B, Kim JL, Benitz WE, Frymoyer A. Clinical Monitoring of Well-Appearing Infants Born to Mothers With Chorioamnionitis. Pediatrics 2018; 141:peds.2017-2056. [PMID: 29599112 DOI: 10.1542/peds.2017-2056] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/11/2017] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND The risk of early-onset sepsis is low in well-appearing late-preterm and term infants even in the setting of chorioamnionitis. The empirical antibiotic strategies for chorioamnionitis-exposed infants that are recommended by national guidelines result in antibiotic exposure for numerous well-appearing, uninfected infants. We aimed to reduce unnecessary antibiotic use in chorioamnionitis-exposed infants through the implementation of a treatment approach that focused on clinical presentation to determine the need for antibiotics. METHODS Within a quality-improvement framework, a new treatment approach was implemented in March 2015. Well-appearing late-preterm and term infants who were exposed to chorioamnionitis were clinically monitored for at least 24 hours in a level II nursery; those who remained well appearing received no laboratory testing or antibiotics and were transferred to the level I nursery or discharged from the hospital. Newborns who became symptomatic were further evaluated and/or treated with antibiotics. Antibiotic use, laboratory testing, culture results, and clinical outcomes were collected. RESULTS Among 277 well-appearing, chorioamnionitis-exposed infants, 32 (11.6%) received antibiotics during the first 15 months of the quality-improvement initiative. No cases of culture result-positive early-onset sepsis occurred. No infant required intubation or inotropic support. Only 48 of 277 (17%) patients had sepsis laboratory testing. The implementation of the new approach was associated with a 55% reduction (95% confidence interval 40%-65%) in antibiotic exposure across all infants ≥34 weeks' gestation born at our hospital. CONCLUSIONS A management approach using clinical presentation to determine the need for antibiotics in chorioamnionitis-exposed infants was successful in reducing antibiotic exposure and was not associated with any clinically relevant delays in care or adverse outcomes.
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Piester T, Frymoyer A, Christofferson M, Yu H, Bass D, Park KT. A Mobile Infliximab Dosing Calculator for Therapy Optimization in Inflammatory Bowel Disease. Inflamm Bowel Dis 2018; 24:227-234. [PMID: 29361094 PMCID: PMC6048868 DOI: 10.1093/ibd/izx037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Indexed: 02/02/2023]
Abstract
BACKGROUND Inadequate infliximab (IFX) drug exposure remains a clinical challenge and leads to high loss of response rates and therapy failure in inflammatory bowel disease (IBD). We aimed to determine the feasibility and pilot effectiveness of a novel, web-based, mobile IFX dosing calculator (mIDC) for therapy optimization. METHODS We developed an mIDC leveraging the known clinical variables of C-reative protein (CRP), albumin, patient's weight, disease activity indices, calprotectin, drug trough levels, and antibodies to IFX that significantly affect pharmacokinetics and/or outcomes. A prospective observational cohort study in pediatric and young adult IBD patients receiving maintenance IFX was performed. System-wide practice adoption of mIDC was achieved through a quality improvement (QI) initiative within a hospital-based infusion unit. RESULTS Forty-nine patients (median age: 16.0 years; 55% female; 65% Crohn's disease) were followed over 9 months. mIDC recommendations for dose optimization were followed by the treating physicians in 198 (89%) out of 222 infusions. Twenty-eight (13%) of 222 mIDC recommendations were to escalate IFX dosing; 15 (54%) of 28 escalation recommendations were declined, and these patients were more likely to already be receiving IFX dose intensification compared with those in whom escalation recommendations were followed (P < 0.05). From mIDC initiation to end of follow-up, mean albumin levels remained unchanged at 3.8 g/dL. Median CRP remained unchanged at 2 g/L. Median calprotectin levels showed a downward trend from 30 to 27 μg/g (n = 9, P < 0.05). The percentage of patients undergoing therapeutic drug monitoring in clinical care increased from 34% to 86% with the QI initiative. The target median IFX trough goal of >5 μg/mL was achieved with 81% probability throughout the QI initiative, an increase of 12% compared with pre-QI values. CONCLUSIONS The use of a novel mIDC is feasible and potentially effective, facilitating both standardization and individualization of therapy in clinical care. mIDC appears to be a practical IFX dosing tool for point-of-care use, leveraging individual pharmacokinetic considerations.
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Frymoyer A. Early career investigator highlight. Pediatr Res 2017; 81:850. [PMID: 28430775 DOI: 10.1038/pr.2017.60] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Accepted: 03/01/2017] [Indexed: 11/09/2022]
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Frymoyer A, Juul SE, Massaro AN, Bammler TK, Wu YW. High-dose erythropoietin population pharmacokinetics in neonates with hypoxic-ischemic encephalopathy receiving hypothermia. Pediatr Res 2017; 81:865-872. [PMID: 28099423 PMCID: PMC5476365 DOI: 10.1038/pr.2017.15] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/28/2016] [Indexed: 12/23/2022]
Abstract
BACKGROUND High-dose erythropoietin (Epo) is a promising neuroprotective treatment in neonates with hypoxic-ischemic encephalopathy (HIE) receiving hypothermia. We evaluated the pharmacokinetics and dose-exposure relationships of high-dose Epo in this population to inform future dosing strategies. METHODS We performed a population pharmacokinetic analysis of 47 neonates with HIE treated with hypothermia who received up to six doses of Epo in two previous clinical trials. We compared the ability of different dosing regimens to achieve the target neuroprotective Epo exposure levels determined from animal models of hypoxic-ischemia (i.e., area under the curve during the first 48 h of treatment (AUC48 h) 140,000 mU*h/ml). RESULTS Birth weight scaled via allometry was a significant predictor of Epo clearance and volume of distribution (P < 0.001). After accounting for birth weight, variation in Epo pharmacokinetics between neonates was low (CV% 20%). All 23 neonates who received 1,000 U/kg every 24 h for the first 2 d of therapy achieved the target AUC48 h 140,000 mU*h/ml. No neonate who received a lower dosing regimen achieved this target. CONCLUSION In neonates with HIE receiving hypothermia, Epo 1,000 U/kg every 24 h for the first 2 d of therapy resulted in consistent achievement of target exposures associated with neuroprotection in animal models.
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Frymoyer A, Bonifacio SL, Drover DR, Su F, Wustoff CJ, Van Meurs KP. Decreased Morphine Clearance in Neonates With Hypoxic Ischemic Encephalopathy Receiving Hypothermia. J Clin Pharmacol 2016; 57:64-76. [PMID: 27225747 DOI: 10.1002/jcph.775] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 04/18/2016] [Accepted: 05/19/2016] [Indexed: 12/19/2022]
Abstract
Morphine is commonly used in neonates with hypothermic ischemic encephalopathy (HIE) during therapeutic hypothermia to provide comfort and analgesia. However, pharmacokinetic data to support morphine dosing in this vulnerable population are lacking. A prospective, 2-center clinical pharmacokinetic study of morphine was conducted in 20 neonates (birthweight, 1.82-5.3 kg) with HIE receiving hypothermia. Morphine dosing was per standard of care at each center. Morphine and glucuronide metabolites (morphine-3-glucuronide and morphine-6-gluronide) were measured via a validated dried blood spot liquid chromatography-tandem mass spectrometry assay. From the available concentration data (n = 106 for morphine; n = 106 for each metabolite), a population pharmacokinetic model was developed using nonlinear mixed-effects modeling. The clearance of morphine and glucuronide metabolites was best predicted by birthweight allometrically scaled using an exponent of 1.23. In addition, the clearance of each glucuronide metabolite was influenced by serum creatinine. No other significant predictors of clearance or volume of distribution were found. For a 3.5-kg neonate, morphine clearance was 0.77 L/h (CV, 48%), and the steady-state volume of distribution was 8.0 L (CV, 49%). Compared with previous studies in full-term newborns without HIE, morphine clearance was markedly lower. Dosing strategies customized for this vulnerable population will be needed. Applying the final population pharmacokinetic model, repeated Monte Carlo simulations (n = 1000 per simulation) were performed to evaluate various morphine dosing strategies that optimized achievement of morphine concentrations between 10 and 40 ng/mL. An optimized morphine loading dose of 50 μg/kg followed by a continuous infusion of 5 μg/kg/h was predicted across birthweights.
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Frymoyer A, Su F, Grimm PC, Sutherland SM, Axelrod DM. Theophylline Population Pharmacokinetics and Dosing in Children Following Congenital Heart Surgery With Cardiopulmonary Bypass. J Clin Pharmacol 2016; 56:1084-93. [PMID: 26712558 DOI: 10.1002/jcph.697] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2015] [Accepted: 12/17/2015] [Indexed: 01/11/2023]
Abstract
Children undergoing cardiac surgery requiring cardiopulmonary bypass (CPB) frequently develop acute kidney injury due to renal ischemia. Theophylline, which improves renal perfusion via adenosine receptor inhibition, is a potential targeted therapy. However, children undergoing cardiac surgery and CPB commonly have alterations in drug pharmacokinetics. To help understand optimal aminophylline (salt formulation of theophylline) dosing strategies in this population, a population-based pharmacokinetic model was developed using nonlinear mixed-effects modeling (NONMEM) from 71 children (median age 5 months; 90% range 1 week to 10 years) who underwent cardiac surgery requiring CPB and received aminophylline as part of a previous randomized controlled trial. A 1-compartment model with linear elimination adequately described the pharmacokinetics of theophylline. Weight scaled via allometry was a significant predictor of clearance and volume. In addition, allometric scaled clearance increased with age implemented as a power maturation function. Compared to prior reports in noncardiac children, theophylline clearance was markedly reduced across age. In the final population pharmacokinetic model, optimized empiric dosing regimens were developed via Monte Carlo simulations. Doses 50% to 75% lower than those recommended in noncardiac children were needed to achieve target serum concentrations of 5 to 10 mg/L.
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Elkomy MH, Drover DR, Glotzbach KL, Galinkin JL, Frymoyer A, Su F, Hammer GB. Pharmacokinetics of Morphine and Its Metabolites in Infants and Young Children After Congenital Heart Surgery. AAPS JOURNAL 2015; 18:124-33. [PMID: 26349564 DOI: 10.1208/s12248-015-9826-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2015] [Accepted: 08/26/2015] [Indexed: 11/30/2022]
Abstract
The objective of this study was to characterize morphine glucuronidation in infants and children following cardiac surgery for possible treatment individualization in this population. Twenty children aged 3 days to 6 years, admitted to the cardiovascular intensive care unit after congenital heart surgery, received an intravenous (IV) loading dose of morphine (0.15 mg/kg) followed by subsequent intermittent IV bolus doses based on a validated pain scale. Plasma samples were collected over 6 h after the loading dose and randomly after follow-up doses to measure morphine and its major metabolite concentrations. A population pharmacokinetic model was developed with the non-linear mixed effects software NONMEM. Parent disposition was adequately described by a linear two-compartment model. Effect of growth (size and maturation) on morphine parameters was accounted for by allometric body weight-based models. An intermediate compartment with Emax model best characterized glucuronide concentrations. Glomerular filtration rate was identified as a significant predictor of glucuronide formation time delay and maximum concentrations. Clearance of morphine in children with congenital heart disease is comparable to that reported in children without cardiac abnormalities of similar age. Children 1-6 months of age need higher morphine doses per kilogram to achieve an area under concentration-time curve comparable to that in older children. Pediatric patients with renal failure receiving morphine therapy are at increased risk of developing opioid toxicity due to accumulation of morphine metabolites.
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Das M, Padda SK, Frymoyer A, Zhou L, Riess JW, Neal JW, Wakelee HA. Dovitinib and erlotinib in patients with metastatic non-small cell lung cancer: A drug-drug interaction. Lung Cancer 2015; 89:280-6. [PMID: 26149476 PMCID: PMC4613811 DOI: 10.1016/j.lungcan.2015.06.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2015] [Revised: 06/11/2015] [Accepted: 06/14/2015] [Indexed: 12/20/2022]
Abstract
INTRODUCTION Erlotinib is a FDA approved small molecule inhibitor of epidermal growth factor receptor and dovitinib is a novel small molecule inhibitor of fibroblast growth factor and vascular endothelial growth factor receptor. This phase 1 trial was conducted to characterize the safety and determine the maximum tolerated dose of erlotinib plus dovitinib in patients with previously treated metastatic non-small cell lung cancer. METHODS Escalating dose cohorts of daily erlotinib and dovitinib dosed 5 days on/2 days off, starting after a 2-week lead-in of erlotinib alone, were planned. A potential pharmacokinetic interaction was hypothesized as dovitinib induces CYP1A1/1A2. Only cohort 1 (150 mg erlotinib+300 mg dovitinib) and cohort -1 (150 mg erlotinib+200mg dovitinib) enrolled. Plasma concentrations of erlotinib were measured pre- and post-dovitinib exposure. RESULTS Two of three patients in cohort 1 had a DLT (grade 3 transaminitis and grade 3 syncope). Two of 6 patients in cohort -1 had a DLT (grade 3 pulmonary embolism and grade 3 fatigue); thus, the study was terminated. Erlotinib exposure (average Cmax 2308±698 ng/ml and AUC 0-24 41,030±15,577 ng×h/ml) approximated previous reports in the six patients with pharmacokinetic analysis. However, erlotinib Cmax and AUC0-24 decreased significantly by 93% (p=0.02) and 97% (p<0.01), respectively, during dovitinib co-administration. CONCLUSIONS This small study demonstrated considerable toxicity and a significant pharmacokinetic interaction with a marked decrease in erlotinib exposure in the presence of dovitinib, likely mediated through CYP1A1/1A2 induction. Given the toxicity and the pharmacokinetic interaction, further investigation with this drug combination will not be pursued.
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Trachtman H, Frymoyer A, Lewandowski A, Greenbaum LA, Feig DI, Gipson DS, Warady BA, Goebel JW, Schwartz GJ, Lewis K, Anand R, Patel UD. Pharmacokinetics, Pharmacodynamics, and Safety of Lisinopril in Pediatric Kidney Transplant Patients: Implications for Starting Dose Selection. Clin Pharmacol Ther 2015; 98:25-33. [PMID: 25807932 PMCID: PMC4536255 DOI: 10.1002/cpt.127] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 03/19/2015] [Indexed: 12/24/2022]
Abstract
Hypertension in pediatric kidney transplant recipients contributes to long-term graft loss, yet treatment options--including angiotensin-converting enzyme inhibitors--are poorly characterized in this vulnerable population. We conducted a multicenter, open-label pharmacokinetic (PK) study of daily oral lisinopril in 22 children (ages 7-17 years) with stable kidney transplant function. Standard noncompartmental PK analyses were performed at steady state. Effects on blood pressure were examined in lisinopril-naïve patients (n = 13). Oral clearance declined in proportion to underlying kidney function; however, in patients with low estimated glomerular filtration rate (30-59 ml/min per 1.73m(2)), exposure (standardized to 0.1 mg/kg/day dose) was within the range reported previously in children without a kidney transplant. In lisinopril-naïve patients, 85% and 77% had a ≥ 6 mmHg reduction in systolic and diastolic blood pressure, respectively. Lisinopril was well tolerated. Our study provides initial insight on lisinopril use in children with a kidney transplant, including starting dose considerations.
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Su F, El-Komy MH, Hammer GB, Frymoyer A, Cohane CA, Drover DR. Population pharmacokinetics of etomidate in neonates and infants with congenital heart disease. Biopharm Drug Dispos 2015; 36:104-14. [PMID: 25377074 DOI: 10.1002/bdd.1924] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2014] [Revised: 10/16/2014] [Accepted: 10/25/2014] [Indexed: 11/10/2022]
Abstract
BACKGROUND Etomidate is a rapid-onset, short-acting hypnotic medication administered for the induction of anesthesia. It is currently approved by the Food and Drug Administration for use in older children and adults. Pharmacokinetic data to help guide dosing in neonates and infants are lacking. OBJECTIVE The aim of this study was to determine the pharmacokinetics of etomidate in neonates and infants with congenital heart disease undergoing cardiac surgery. METHODS Four neonates and 16 infants, postnatal age 0.3-11.7 months, requiring open-heart surgery received 0.3 mg/kg of etomidate administered as a single intravenous dose prior to surgery. Blood sampling for plasma etomidate concentration occurred immediately following etomidate administration until the initiation of cardiopulmonary bypass. A population pharmacokinetic approach using nonlinear mixed-effects modeling was applied to characterize etomidate pharmacokinetics. RESULTS The pharmacokinetics of etomidate was described by a two-compartment model with first-order elimination. An allometric weight-based model was applied to scale results to a 70 kg adult. Covariates including age and cardiac physiology were not found significantly to impact etomidate pharmacokinetics. The study population was found to have a central and intercompartmental clearance of 0.624 l/min/70 kg and 0.44 l/min/70 kg, respectively; central and peripheral distribution volume of 9.47 l/70 kgand 22.8 l/70 kg, respectively. Inter-individual variability was 94-142% for all parameters and the residual variability was 29%. CONCLUSIONS The clearance of etomidate is lower in neonates and infants with congenital heart disease compared with published values for older children without congenital heart disease. In addition, etomidate pharmacokinetics is highly variable in this pediatric cardiac population.
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Yago MR, Frymoyer A, Benet LZ, Smelick GS, Frassetto LA, Ding X, Dean B, Salphati L, Budha N, Jin JY, Dresser MJ, Ware JA. The use of betaine HCl to enhance dasatinib absorption in healthy volunteers with rabeprazole-induced hypochlorhydria. AAPS JOURNAL 2014; 16:1358-65. [PMID: 25274610 DOI: 10.1208/s12248-014-9673-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 09/11/2014] [Indexed: 11/30/2022]
Abstract
Many orally administered, small-molecule, targeted anticancer drugs, such as dasatinib, exhibit pH-dependent solubility and reduced drug exposure when given with acid-reducing agents. We previously demonstrated that betaine hydrochloride (BHCl) can transiently re-acidify gastric pH in healthy volunteers with drug-induced hypochlorhydria. In this randomized, single-dose, three-way crossover study, healthy volunteers received dasatinib (100 mg) alone, after pretreatment with rabeprazole, and with 1500 mg BHCl after rabeprazole pretreatment, to determine if BHCl can enhance dasatinib absorption in hypochlorhydric conditions. Rabeprazole (20 mg b.i.d.) significantly reduced dasatinib Cmax and AUC0-∞ by 92 and 78%, respectively. However, coadministration of BHCl significantly increased dasatinib Cmax and AUC0-∞ by 15- and 6.7-fold, restoring them to 105 and 121%, respectively, of the control (dasatinib alone). Therefore, BHCl reversed the impact of hypochlorhydria on dasatinib drug exposure and may be an effective strategy to mitigate potential drug-drug interactions for drugs that exhibit pH-dependent solubility and are administered orally under hypochlorhydric conditions.
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Sampson MR, Frymoyer A, Rattray B, Cotten CM, Smith B, Capparelli E, Bonifacio SL, Cohen-Wolkowiez M. Predictive performance of a gentamicin population pharmacokinetic model in neonates receiving full-body hypothermia. Ther Drug Monit 2014; 36:584-9. [PMID: 25225917 PMCID: PMC4166612 DOI: 10.1097/ftd.0000000000000056] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Population pharmacokinetic (popPK) models derived from small pharmacokinetics (PK) studies in neonates are often underpowered to detect clinically important characteristics that drive dosing. External validation of such models is crucial. In this study, the predictive performance of a gentamicin popPK model in neonates receiving hypothermia was evaluated. METHODS A previously published gentamicin popPK model was developed in neonates with hypoxic ischemic encephalopathy undergoing hypothermia using a retrospective single-institution (University of California-San Francisco) data set. The predictive performance of this model was evaluated in an external retrospective data set from the University of California-San Francisco (validation A) and another from Duke University (validation B). Both institutions used the same hypothermia protocol and collected similar clinical and PK data. Gentamicin dosing and samples were collected per routine care. Predictive performance was evaluated by quantifying the accuracy and precision of model predictions and using simulation-based diagnostics to detect bias in predictions. RESULTS Forty-one neonates (n = 18 validation A; n = 23 validation B) with median (range) gestational age of 40 weeks (33-42) and birth weight of 3.3 kg (1.9-4.6) and 76 samples (55% troughs, 33% and 28% drawn at 24 and 36 hours after dose, respectively) were analyzed. The model adequately predicted gentamicin concentrations from the same institution (validation A; median average fold error = 1.1 and numerical prediction distribution error P > 0.05) but underpredicted concentrations from the outside institution (validation B; median average fold error = 0.6 and numerical prediction distribution error P < 0.05). CONCLUSIONS The model demonstrated adequate predictive performance for an external data set in the same institution but not from an outside institution. Larger sample sizes, use of data from multiple institutions, and external evaluation in development of popPK models in neonates may improve generalizability of dosing recommendations arising from single-institution studies.
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Smelick GS, Heffron TP, Chu L, Dean B, West DA, Duvall SL, Lum BL, Budha N, Holden SN, Benet LZ, Frymoyer A, Dresser MJ, Ware JA. Prevalence of acid-reducing agents (ARA) in cancer populations and ARA drug-drug interaction potential for molecular targeted agents in clinical development. Mol Pharm 2013; 10:4055-62. [PMID: 24044612 DOI: 10.1021/mp400403s] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Acid-reducing agents (ARAs) are the most commonly prescribed medications in North America and Western Europe. There are currently no data describing the prevalence of their use among cancer patients. However, this is a paramount question due to the potential for significant drug-drug interactions (DDIs) between ARAs, most commonly proton pump inhibitors (PPIs), and orally administered cancer therapeutics that display pH-dependent solubility, which may lead to decreased drug absorption and decreased therapeutic benefit. Of recently approved orally administered cancer therapeutics, >50% are characterized as having pH-dependent solubility, but there are currently no data describing the potential for this ARA-DDI liability among targeted agents currently in clinical development. The objectives of this study were to (1) determine the prevalence of ARA use among different cancer populations and (2) investigate the prevalence of orally administered cancer therapeutics currently in development that may be liable for an ARA-DDI. To address the question of ARA use among cancer patients, a retrospective cross-sectional analysis was performed using two large healthcare databases: Thomson Reuters MarketScan (N = 1,776,443) and the U.S. Department of Veterans Affairs (VA, N = 1,171,833). Among all cancer patients, the total prevalence proportion of ARA use (no. of cancer patients receiving an ARA/total no. of cancer patients) was 20% and 33% for the MarketScan and VA databases, respectively. PPIs were the most commonly prescribed agent, comprising 79% and 65% of all cancer patients receiving a prescription for an ARA (no. of cancer patients receiving a PPI /no. of cancer patients receiving an ARA) for the MarketScan and VA databases, respectively. To estimate the ARA-DDI liability of orally administered molecular targeted cancer therapeutics currently in development, two publicly available databases, (1) Kinase SARfari and (2) canSAR, were examined. For those orally administered clinical candidates that had available structures, the pKa's and corresponding relative solubilities were calculated for a normal fasting pH of 1.2 and an "ARA-hypochlorhydric" pH of 4. Taking calculated pKa's and relative solubilities into consideration, clinical candidates were classified based on their risk for an ARA-DDI. More than one-quarter (28%) of the molecules investigated are at high risk for an ARA-DDI, and of those high risk molecules, nearly three-quarters (73%) are being clinically evaluated for at least one of five cancer types with the highest prevalence of ARA use (gastrointestinal, pancreatic, lung, glioblastoma multiforme, gastrointestinal stromal tumor (GIST)). These data strongly suggest that with the clinical development of ARA-DDI-susceptible cancer therapeutics will come continued challenges for drug-development scientists, oncologists, and regulatory agencies in ensuring that patients achieve safe and efficacious exposures of their cancer therapeutics and thus optimal patient outcomes.
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Frymoyer A. Vancomycin Dosing Practices, Trough Concentrations, and Predicted Area Under the Curve in Children With Suspected Invasive Staphylococcal Infections. J Pediatric Infect Dis Soc 2013; 2:291-2. [PMID: 26619486 DOI: 10.1093/jpids/pit031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Frymoyer A, Meng L, Bonifacio SL, Verotta D, Guglielmo BJ. Gentamicin pharmacokinetics and dosing in neonates with hypoxic ischemic encephalopathy receiving hypothermia. Pharmacotherapy 2013; 33:718-26. [PMID: 23553582 DOI: 10.1002/phar.1263] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
STUDY OBJECTIVE To evaluate the pharmacokinetics of gentamicin in neonates with hypoxic ischemic encephalopathy (HIE) receiving hypothermia and to identify an empiric gentamicin dosing strategy in this population that optimizes achievement of target peak and trough concentrations. DESIGN Population pharmacokinetic study using retrospective medical record data. SETTING Tertiary neonatal intensive care unit. PATIENTS A total of 29 full-term neonates diagnosed with HIE treated with hypothermia who received gentamicin and underwent therapeutic drug monitoring MEASUREMENT AND MAIN RESULTS Patient demographics and gentamicin concentration data were retrospectively collected over a 2-year period. A population-based pharmacokinetic model was developed using nonlinear mixed-effects modeling (NONMEM). Using the developed model, Monte Carlo simulations were performed to evaluate the probability of achieving target peak (> 6 mg/L) and trough (< 2 mg/L) gentamicin concentrations for various potential dosing regimens. A one-compartment model best described the available gentamicin concentration data. Birthweight and serum creatinine significantly influenced gentamicin clearance. For the typical study neonate (birthweight 3.3 kg, serum creatinine 0.9 mg/dl), clearance was 0.034 L/hour/kg and volume was 0.52 L/kg. At a 24-hour dosing interval, Monte Carlo simulations predicted target gentamicin peak and trough concentrations could not be reliably achieved at any dose. At a 36-hour dosing interval, a dose of 4-5 mg/kg is predicted to achieve target gentamicin peak and trough concentrations in more than 90% of neonates. CONCLUSIONS Gentamicin clearance is decreased in neonates with HIE treated with hypothermia compared with previous reports in nonasphyxiated normothermic full-term neonates. A prolonged 36-hour dosing interval will be needed to achieve target gentamicin trough concentrations in this population. Further prospective evaluation of this dosing recommendation is needed.
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