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Fernandez Hernandez S, Barlow B, Pertsovskaya V, Maciel CB. Temperature Control After Cardiac Arrest: A Narrative Review. Adv Ther 2023; 40:2097-2115. [PMID: 36964887 PMCID: PMC10129937 DOI: 10.1007/s12325-023-02494-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 03/08/2023] [Indexed: 03/26/2023]
Abstract
Cardiac arrest (CA) is a critical public health issue affecting more than half a million Americans annually. The main determinant of outcome post-CA is hypoxic-ischemic brain injury (HIBI), and temperature control is currently the only evidence-based, guideline-recommended intervention targeting secondary brain injury. Temperature control is a key component of a post-CA care bundle; however, conflicting evidence challenges its wide implementation across the vastly heterogeneous population of CA survivors. Here, we critically appraise the available literature on temperature control in HIBI, detail how the evidence has been integrated into clinical practice, and highlight the complications associated with its use and the timing of neuroprognostication after CA. Future clinical trials evaluating different temperature targets, rates of rewarming, duration of cooling, and identifying which patient phenotype benefits from different temperature control methods are needed to address these prevailing knowledge gaps.
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Affiliation(s)
| | - Brooke Barlow
- Department of Pharmacy, Memorial Hermann the Woodlands Medical Center, The Woodlands, TX, USA
| | - Vera Pertsovskaya
- The George Washington University School of Medicine and Health Sciences, Washington, DC, 20037, USA
| | - Carolina B Maciel
- Department of Neurology, University of Florida College of Medicine, Gainesville, FL, 32611, USA
- Department of Neurosurgery, University of Florida College of Medicine, Gainesville, FL, 32611, USA
- Comprehensive Epilepsy Center, Department of Neurology, Yale University School of Medicine, New Haven, CT, USA
- Department of Neurology, University of Utah, Salt Lake City, UT, 84132, USA
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Chalia M, Hartmann H, Pressler R. Practical Approaches to the Treatment of Neonatal Seizures. Curr Treat Options Neurol 2022. [DOI: 10.1007/s11940-022-00711-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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3
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Poppe M, Clodi C, Schriefl C, Mueller M, Sunder-Plaßmann R, Reiter B, Rechenmacher M, van Os W, van Hasselt JGC, Holzer M, Herkner H, Schwameis M, Jilma B, Schoergenhofer C, Weiser C. Targeted temperature management after cardiac arrest is associated with reduced metabolism of pantoprazole - A probe drug of CYP2C19 metabolism. Biomed Pharmacother 2021; 146:112573. [PMID: 34959115 DOI: 10.1016/j.biopha.2021.112573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 12/16/2021] [Accepted: 12/19/2021] [Indexed: 11/02/2022] Open
Abstract
OBJECTIVE Targeted temperature management (TTM) is part of standard post-resuscitation care. TTM may downregulate cytochrome enzyme activity and thus impact drug metabolism. This study compared the pharmacokinetics (PK) of pantoprazole, a probe drug of CYP2C19-dependent metabolism, at different stages of TTM following cardiac arrest. METHODS This prospective controlled study was performed at the Medical University of Vienna and enrolled 16 patients following cardiac arrest. The patients completed up to three study periods (each lasting 24 h) in which plasma concentrations of pantoprazole were quantified: (P1) hypothermia (33 °C) after admission, (P2) normothermia after rewarming (36 °C, intensive care), and (P3) normothermia during recovery (normal ward, control group). PK was analysed using non-compartmental analysis and nonlinear mixed-effects modelling. RESULTS 16 patients completed periods P1 and P2; ten completed P3. The median half-life of pantoprazole was 2.4 h (quartiles: 1.8-4.8 h) in P1, 2.8 h (2.1-6.8 h, p = 0.046 vs. P1, p = 0.005 vs. P3) in P2 and 1.2 h (0.9 - 2.3 h, p = 0.007 vs. P1) in P3. A two-compartment model described the PK data best. Typical values for clearance were estimated separately for each study period, indicating 40% and 29% reductions during P1 and P2, respectively, compared to P3. The central volume of distribution was estimated separately for P2, indicating a 64% increase compared to P1 and P3. CONCLUSION CYP2C19-dependent drug metabolism is downregulated during TTM following cardiac arrest. These results may influence drug choice and dosing of similarly metabolized drugs and may be helpful for designing studies in similar clinical situations.
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Affiliation(s)
- Michael Poppe
- Department of Emergency Medicine, Medical University of Vienna, Austria
| | - Christian Clodi
- Department of Emergency Medicine, Medical University of Vienna, Austria
| | | | - Matthias Mueller
- Department of Emergency Medicine, Medical University of Vienna, Austria
| | - Raute Sunder-Plaßmann
- Clinical Institute of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | - Birgit Reiter
- Clinical Institute of Laboratory Medicine, Medical University of Vienna, Vienna, Austria
| | | | - Wisse van Os
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | | | - Michael Holzer
- Department of Emergency Medicine, Medical University of Vienna, Austria
| | - Harald Herkner
- Department of Emergency Medicine, Medical University of Vienna, Austria
| | - Michael Schwameis
- Department of Emergency Medicine, Medical University of Vienna, Austria
| | - Bernd Jilma
- Department of Clinical Pharmacology, Medical University of Vienna, Austria
| | | | - Christoph Weiser
- Department of Emergency Medicine, Medical University of Vienna, Austria
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Bohannon KK, Leung N, Cook AM, Autry E, Gibson J, Naranjo V, Baumann R, Gardner B. Evaluation of Two Fosphenytoin Loading Dose Regimens and Monitoring in Infants and Neonates Less Than Six Months of Age. J Pediatr Pharmacol Ther 2020; 25:617-622. [PMID: 33041716 DOI: 10.5863/1551-6776-25.7.617] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVES The objectives of the study were to compare the free serum concentrations after different fosphenytoin loading dose strategies in patients younger than 6 months old and to investigate the frequency of seizure cessation following a loading dose of fosphenytoin. METHODS This retrospective cohort study included neonates and infants admitted to a 150-bed children's hospital between August 1, 2014, and February 1, 2018. Patients were included if they were younger than 6 months old and had a postload free phenytoin serum concentration collected during the specified time frame. Patients were identified through a database query screening for the inclusion criteria. Patients were separated into 2 groups with the 15 mg/kg group as per protocol and the 20 mg/kg group as noted in common practice. Data collection included demographic information, fosphenytoin dose, time of administration of the fosphenytoin loading dose, time of sampling, free phenytoin serum concentration results, concomitant antiepileptic agents, albumin serum concentration, and total bilirubin serum concentration. RESULTS Forty-one patients were included for analysis, 12 in the 15 mg/kg group and 29 in the 20 mg/kg group. The average free phenytoin concentration after the loading dose was 2.45 ± 0.54 mg/L in the 15 mg/kg group and 2.52 ± 0.66 mg/L in the 20 mg/kg group. Seizure cessation after the fosphenytoin loading dose was achieved in 3 of 12 (25%) patients in the 15 mg/kg group and in 13 of 29 (45%) patients in the 20 mg/kg group (p = 0.305). CONCLUSIONS The study demonstrates that a traditional range of fosphenytoin loading dose (15-20 mg/kg) led to elevated postloading dose free phenytoin serum concentrations in the majority of patients with a seizure cessation rate of approximately 39%. The question remains as to what the optimal dose and target concentration should be in this patient population to achieve the best efficacy without risking associated toxicities.
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Aflaki K, Bhuptani P, Aflaki S. Phenytoin Pharmacokinetics and Cardiopulmonary Bypass: A Case of Seizures in the Postoperative Period. J Cardiothorac Vasc Anesth 2019; 34:747-752. [PMID: 31852595 DOI: 10.1053/j.jvca.2019.10.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 10/22/2019] [Accepted: 10/28/2019] [Indexed: 11/11/2022]
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Eyileten C, Soplinska A, Pordzik J, Siller‐Matula JM, Postuła M. Effectiveness of Antiplatelet Drugs Under Therapeutic Hypothermia: A Comprehensive Review. Clin Pharmacol Ther 2019; 106:993-1005. [DOI: 10.1002/cpt.1492] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Accepted: 04/12/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Ceren Eyileten
- Department of Experimental and Clinical PharmacologyCenter for Preclinical Research and Technology CEPTMedical University of Warsaw Warsaw Poland
| | - Aleksandra Soplinska
- Department of Experimental and Clinical PharmacologyCenter for Preclinical Research and Technology CEPTMedical University of Warsaw Warsaw Poland
| | - Justyna Pordzik
- Department of Experimental and Clinical PharmacologyCenter for Preclinical Research and Technology CEPTMedical University of Warsaw Warsaw Poland
| | | | - Marek Postuła
- Department of Experimental and Clinical PharmacologyCenter for Preclinical Research and Technology CEPTMedical University of Warsaw Warsaw Poland
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Boylan GB, Kharoshankaya L, Mathieson SR. Diagnosis of seizures and encephalopathy using conventional EEG and amplitude integrated EEG. Handb Clin Neurol 2019; 162:363-400. [PMID: 31324321 DOI: 10.1016/b978-0-444-64029-1.00018-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Seizures are more common in the neonatal period than at any other time of life, partly due to the relative hyperexcitability of the neonatal brain. Brain monitoring of sick neonates in the NICU using either conventional electroencephalography or amplitude integrated EEG is essential to accurately detect seizures. Treatment of seizures is important, as evidence increasingly indicates that seizures damage the brain in addition to that caused by the underlying etiology. Prompt treatment has been shown to reduce seizure burden with the potential to ameliorate seizure-mediated damage. Neonatal encephalopathy most commonly caused by a hypoxia-ischemia results in an alteration of mental status and problems such as seizures, hypotonia, apnea, and feeding difficulties. Confirmation of encephalopathy with EEG monitoring can act as an important adjunct to other investigations and the clinical examination, particularly when considering treatment strategies such as therapeutic hypothermia. Brain monitoring also provides useful early prognostic indicators to clinicians. Recent use of machine learning in algorithms to continuously monitor the neonatal EEG, detect seizures, and grade encephalopathy offers the exciting prospect of real-time decision support in the NICU in the very near future.
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Affiliation(s)
- Geraldine B Boylan
- Department of Paediatrics and Child Health, Irish Centre for Fetal and Neonatal Translational Research (INFANT), University College Cork, Cork, Ireland.
| | - Liudmila Kharoshankaya
- Department of Paediatrics and Child Health, Irish Centre for Fetal and Neonatal Translational Research (INFANT), University College Cork, Cork, Ireland
| | - Sean R Mathieson
- Department of Paediatrics and Child Health, Irish Centre for Fetal and Neonatal Translational Research (INFANT), University College Cork, Cork, Ireland
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Abstract
A 60-year-old man with cerebral palsy and epilepsy was admitted with acute lethargy and deterioration in coordination. He was noted to be hypothermic at 35°C on admission. Routine work-up revealed toxic levels of phenytoin. No cause of hypothermia could be identified but as his phenytoin levels normalised, his body temperature also improved. There are three other reported cases of phenytoin- induced hypothermia in the literature. Could this be a rare cause of hypothermia?
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Figueroa SA, Blissitt PA, Livesay S, Wavra T, Guanci MM. Clinical Q & A: Translating Therapeutic Temperature Management from Theory to Practice. Ther Hypothermia Temp Manag 2017; 7:231-234. [PMID: 29058528 DOI: 10.1089/ther.2017.29037.mkb] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Stephen A Figueroa
- 2 Division of Neurocritical Care, The University of Texas Southwestern Medical Center , Dallas, Texas
| | - Patricia A Blissitt
- 3 Harborview Medical Center and Swedish Medical Center, Clinical Faculty, University of Washington School of Nursing , Seattle, Washington
| | - Sarah Livesay
- 4 College of Nursing, Rush University , Chicago, Illinois
| | - Teresa Wavra
- 5 Cardiovascular CNS, Mission Hospital , Mission Viejo, California
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Madden LK, Hill M, May TL, Human T, Guanci MM, Jacobi J, Moreda MV, Badjatia N. The Implementation of Targeted Temperature Management: An Evidence-Based Guideline from the Neurocritical Care Society. Neurocrit Care 2017; 27:468-487. [DOI: 10.1007/s12028-017-0469-5] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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Donovan MD, Griffin BT, Kharoshankaya L, Cryan JF, Boylan GB. Pharmacotherapy for Neonatal Seizures: Current Knowledge and Future Perspectives. Drugs 2016; 76:647-61. [DOI: 10.1007/s40265-016-0554-7] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Šunjić KM, Webb AC, Šunjić I, Palà Creus M, Folse SL. Pharmacokinetic and Other Considerations for Drug Therapy During Targeted Temperature Management: . Crit Care Med 2015; 43:2228-38. [DOI: 10.1097/ccm.0000000000001223] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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13
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Miyamoto H, Matsueda S, Moritsuka A, Shimokawa K, Hirata H, Nakashima M, Sasaki H, Fumoto S, Nishida K. Evaluation of hypothermia on the in vitro metabolism and binding and in vivo disposition of midazolam in rats. Biopharm Drug Dispos 2015; 36:481-9. [PMID: 26037413 DOI: 10.1002/bdd.1960] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 05/10/2015] [Accepted: 05/20/2015] [Indexed: 01/16/2023]
Abstract
The effect of hypothermia on the in vivo pharmacokinetics of midazolam was evaluated, with a focus on altered metabolism in the liver and binding to serum proteins. Rat primary hepatocytes were incubated with midazolam (which is metabolized mainly by CYP3A2) at 37, 32 or 28 °C. The Michaelis-Menten constant (Km) and maximum velocity (Vmax) of midazolam were estimated using the Michaelis-Menten equation. The Km of CYP3A2 midazolam remained unchanged, but the Vmax decreased at 28 °C. In rats, whose temperature was maintained at 37, 32 or 28 °C by a heat lamp or ice pack, the plasma concentrations of midazolam were higher, whereas those in the brain and liver were unchanged at 28 °C. The tissue/plasma concentration ratios were, however, increased significantly. The unbound fraction of midazolam in serum at 28 °C was half that at 37 °C. These pharmacokinetic changes associated with hypothermic conditions were due to reductions in CYP3A2 activity and protein binding.
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Affiliation(s)
| | - Satoshi Matsueda
- Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Akihiro Moritsuka
- Department of Hospital Pharmacy, Nagasaki University Hospital, Japan
| | - Kenta Shimokawa
- Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Haruna Hirata
- Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Mikiro Nakashima
- Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Hitoshi Sasaki
- Department of Hospital Pharmacy, Nagasaki University Hospital, Japan
| | - Shintaro Fumoto
- Graduate School of Biomedical Sciences, Nagasaki University, Japan
| | - Koyo Nishida
- Graduate School of Biomedical Sciences, Nagasaki University, Japan
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Beseda R, Smith S, Veenstra A. Therapeutic hypothermia after cardiac arrest and return of spontaneous circulation: it's complicated. Crit Care Nurs Clin North Am 2014; 26:511-24. [PMID: 25438893 DOI: 10.1016/j.ccell.2014.08.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Providing evidence-based care to patients with return of spontaneous circulation after a cardiac arrest is a recent complex innovation. Once resuscitated patients must be assessed for appropriateness for therapeutic hypothermia, be cooled in a timely manner, maintained while hypothermic, rewarmed within a specified time frame, and then assessed for whether hypothermia was successful for the patient through neuroprognostication. Nurses caring for therapeutic hypothermia patients must be knowledgeable and prepared to provide care to the patient and family. This article provides an overview of the complexity of therapeutic hypothermia for patients with return of spontaneous circulation in the form of a case study.
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Affiliation(s)
- Ryan Beseda
- Department of Critical Care Services, Baylor University Medical Center at Dallas, 3500 Gaston Avenue, Dallas, TX 75246, USA
| | - Susan Smith
- Department of Critical Care Services, Baylor University Medical Center at Dallas, 3500 Gaston Avenue, Dallas, TX 75246, USA.
| | - Amy Veenstra
- Department of Nursing Administration, Baylor University Medical Center at Dallas, 3500 Gaston Avenue, Dallas, TX 75246, USA
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Noyes AM, Lundbye JB. Managing the Complications of Mild Therapeutic Hypothermia in the Cardiac Arrest Patient. J Intensive Care Med 2013; 30:259-69. [PMID: 24371249 DOI: 10.1177/0885066613516416] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Accepted: 09/27/2013] [Indexed: 12/11/2022]
Abstract
Mild therapeutic hypothermia (MTH) is used to lower the core body temperature of cardiac arrest (CA) patients to 32°C from 34°C to provide improved survival and neurologic outcomes after resuscitation from in-hospital or out-of-hospital CA. Despite the improved benefits of MTH, there are potentially unforeseen complications associated during management. Although the adverse effects are transient, the clinician should be aware of the associated complications when managing the patient receiving MTH. We aim to provide the medical community comprehensive information related to the potential complications of survivors of CA receiving MTH, as it is imperative for the clinician to understand the physiologic changes that take place in the patient receiving MTH and how to prepare for them and manage them if they do occur. We hope to provide information of how to manage these potential complications through both a review of the current literature and a reflection of our own experience.
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Affiliation(s)
- Adam M Noyes
- Department of Medicine, University of Connecticut Medical School, Farmington, CT, USA
| | - Justin B Lundbye
- Division of Cardiology, the Hospital of Central Connecticut, Chief of Cardiology, New Britain, CT, USA
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Empey PE, Velez de Mendizabal N, Bell MJ, Bies RR, Anderson KB, Kochanek PM, Adelson PD, Poloyac SM. Therapeutic hypothermia decreases phenytoin elimination in children with traumatic brain injury. Crit Care Med 2013; 41:2379-87. [PMID: 23896831 PMCID: PMC3783553 DOI: 10.1097/ccm.0b013e318292316c] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Preclinical and clinical studies have suggested that therapeutic hypothermia, while decreasing neurologic injury, may also lead to drug toxicity that may limit its benefit. Cooling decreases cytochrome P450 (CYP)-mediated drug metabolism, and limited clinical data suggest that drug levels are elevated. Fosphenytoin is metabolized by cytochrome P450 2C, has a narrow therapeutic range, and is a commonly used antiepileptic medication. The objective of this study was to evaluate the impact of therapeutic hypothermia on phenytoin levels and pharmacokinetics in children with severe traumatic brain injury. DESIGN Pharmacokinetic analysis of subjects participating in a multicenter randomized phase III study of therapeutic hypothermia for severe traumatic brain injury. SETTING ICU at the Children's Hospital of Pittsburgh. PATIENTS Nineteen children with severe traumatic brain injury. INTERVENTIONS None. MEASUREMENTS AND MAIN RESULTS A sum of 121 total and 114 free phenytoin levels were evaluated retrospectively in 10 hypothermia-treated and nine normothermia-treated children who were randomized to 48 hours of cooling to 32-33°C followed by slow rewarming or controlled normothermia. Drug dosing, body temperatures, and demographics were collected during cooling, rewarming, and posttreatment periods (8 d). A trend toward elevated free phenytoin levels in the hypothermia group (p=0.051) to a median of 2.2 mg/L during rewarming was observed and was not explained by dosing differences. Nonlinear mixed-effects modeling incorporating both free and total levels demonstrated that therapeutic hypothermia specifically decreased the time-variant component of the maximum velocity of phenytoin metabolism (Vmax) 4.6-fold (11.6-2.53 mg/hr) and reduced the overall Vmax by ~50%. Simulations showed that the increased risk for drug toxicity extends many days beyond the end of the cooling period. CONCLUSIONS Therapeutic hypothermia significantly reduces phenytoin elimination in children with severe traumatic brain injury leading to increased drug levels for an extended period of time after cooling. Pharmacokinetic interactions between hypothermia and medications should be considered when caring for children receiving this therapy.
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Affiliation(s)
- Philip E Empey
- 1Department of Pharmacy and Therapeutics, Center for Clinical Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA. 2Division of Clinical Pharmacology, School of Medicine and Indiana Clinical and Translational Sciences Institute, Indiana University, Indianapolis, IN. 3Department of Critical Care Medicine, School of Medicine, and the Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA. 4Department of Neurological Surgery, School of Medicine, and the Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA. 5Department of Pharmaceutical Sciences, Center for Clinical Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburgh, PA. 6Division of Neurosurgery/Children's Neuroscience, Department of Child Health, Barrow Neurological Institute, Phoenix Children's Hospital, Phoenix, AZ
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Miyamoto H, Matsueda S, Komori K, Fumoto S, Nakashima M, Yoshikawa N, Hirata H, Shimokawa K, Ohwaki Y, Nishida K. Evaluation for effect of hypothermia on the disposition of 4-nitrophenol in rats by in-vitro metabolism study and rat liver perfusion system. J Pharm Pharmacol 2013; 65:1536-40. [DOI: 10.1111/jphp.12130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Accepted: 07/23/2013] [Indexed: 11/26/2022]
Abstract
Abstract
Objectives
The aim of this study was to evaluate the effect of hypothermia on the in-vivo pharmacokinetics of 4-nitrophenol (4NP) using rat liver homogenate and rat liver perfusion system.
Methods
Rat liver homogenate was incubated with 4NP, which is mainly metabolized by cytochrome P450 2E1, at 37, 34, 32 or 28°C. The Michaelis constant (Km) and maximum elimination velocity (Vmax) of 4NP were calculated by a Hanes–Woolf plot. The hepatic extraction ratio (Eh) of 4NP was evaluated in a rat liver perfusion study at 37, 34, 32 or 28°C. Moreover, the plasma concentration profiles of 4NP after its intravenous (i.v.) administration to rats were analysed by the moment theory and were compared with in-vitro parameters.
Key findings
While the Km of 4NP was not changed, the Vmax and Eh were reduced at low temperatures. The plasma concentrations of 4NP after its i.v. administration to rats were significantly increased at 28°C.
Conclusion
Changes in the pharmacokinetics of 4NP under hypothermic conditions were caused by alterations in Vmax and Eh. We may be able to predict the disposition of a drug by in-vitro studies.
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Affiliation(s)
- Hirotaka Miyamoto
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Satoshi Matsueda
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Kotaro Komori
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Shintaro Fumoto
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Mikiro Nakashima
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Naoki Yoshikawa
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Haruna Hirata
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Kenta Shimokawa
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Yuichi Ohwaki
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Koyo Nishida
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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Bjelland TW, Klepstad P, Haugen BO, Nilsen T, Dale O. Effects of Hypothermia on the Disposition of Morphine, Midazolam, Fentanyl, and Propofol in Intensive Care Unit Patients. Drug Metab Dispos 2012; 41:214-23. [DOI: 10.1124/dmd.112.045567] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Wildschut ED, van Saet A, Pokorna P, Ahsman MJ, Van den Anker JN, Tibboel D. The impact of extracorporeal life support and hypothermia on drug disposition in critically ill infants and children. Pediatr Clin North Am 2012; 59:1183-204. [PMID: 23036251 PMCID: PMC4709257 DOI: 10.1016/j.pcl.2012.07.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Extracorporeal membrane oxygenation (ECMO) support is an established lifesaving therapy for potentially reversible respiratory or cardiac failure. In 10% of all pediatric patients receiving ECMO, ECMO therapy is initiated during or after cardiopulmonary resuscitation. Therapeutic hypothermia is frequently used in children after cardiac arrest, despite the lack of randomized controlled trials that show its efficacy. Hypothermia is frequently used in children and neonates during cardiopulmonary bypass (CPB). By combining data from pharmacokinetic studies in children on ECMO and CPB and during hypothermia, this review elucidates the possible effects of hypothermia during ECMO on drug disposition.
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Affiliation(s)
- Enno D. Wildschut
- Department of Pediatric Surgery, Intensive Care, Erasmus MC-Sophia Children’s Hospital, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands,Corresponding author. Department of Pediatric Surgery, Intensive Care, Erasmus MC-Sophia Children’s Hospital, Dr Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands.
| | - Annewil van Saet
- Department of Pediatric Surgery, Intensive Care, Erasmus MC-Sophia Children’s Hospital, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands,Department of Cardio-Thoracic Anesthesiology, Erasmus MC, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands
| | - Pavla Pokorna
- Department of Pediatric Surgery, Intensive Care, Erasmus MC-Sophia Children’s Hospital, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands,Faculty of Medicine, Department of Pediatrics, PICU/NICU, Charles University, ke Karlovu 2, Praha 2, 121 00 Prague, Czech Republic
| | - Maurice J. Ahsman
- LAP&P Consultants BV, Archimedesweg 31, 2333 CM, Leiden, The Netherlands
| | - John N. Van den Anker
- Department of Pediatric Surgery, Intensive Care, Erasmus MC-Sophia Children’s Hospital, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands,Division of Pediatric Clinical Pharmacology, Children’s National Medical Center, Sheikh Zayed Campus for Advanced Children’s Medicine, 111 Michigan Avenue, NW, Washington, DC 20010, USA,Department of Pediatrics, School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA,Department of Pharmacology & Physiology, School of Medicine and Health Sciences, The George Washington University, Washington, DC, USA
| | - Dick Tibboel
- Department of Pediatric Surgery, Intensive Care, Erasmus MC-Sophia Children’s Hospital, Dr. Molewaterplein 60, 3015 GJ Rotterdam, The Netherlands
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Alam HB, Pusateri AE, Kindzelski A, Egan D, Hoots K, Andrews MT, Rhee P, Tisherman S, Mann K, Vostal J, Kochanek PM, Scalea T, Deal V, Sheppard F, Sopko G. Hypothermia and hemostasis in severe trauma: A new crossroads workshop report. J Trauma Acute Care Surg 2012; 73:809-17. [DOI: 10.1097/ta.0b013e318265d1b8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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23
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Poles JC, Vadeboncoeur TF, Bobrow BJ. Persistent Ventricular Fibrillation During Therapeutic Hypothermia and Prolonged High-Dose Vasopressor Therapy: Case Report. J Emerg Med 2012; 43:36-40. [DOI: 10.1016/j.jemermed.2009.05.027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2009] [Revised: 03/16/2009] [Accepted: 05/08/2009] [Indexed: 10/20/2022]
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de Haan TR, Bijleveld YA, van der Lee JH, Groenendaal F, van den Broek MPH, Rademaker CMA, van Straaten HLM, van Weissenbruch MM, Vermeulen JR, Dijk PH, Dudink J, Rijken M, van Heijst A, Dijkman KP, Gavilanes D, van Kaam AH, Offringa M, Mathôt RAA. Pharmacokinetics and pharmacodynamics of medication in asphyxiated newborns during controlled hypothermia. The PharmaCool multicenter study. BMC Pediatr 2012; 12:45. [PMID: 22515424 PMCID: PMC3358232 DOI: 10.1186/1471-2431-12-45] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2011] [Accepted: 04/19/2012] [Indexed: 01/12/2023] Open
Abstract
Background In the Netherlands, perinatal asphyxia (severe perinatal oxygen shortage) necessitating newborn resuscitation occurs in at least 200 of the 180–185.000 newly born infants per year. International randomized controlled trials have demonstrated an improved neurological outcome with therapeutic hypothermia. During hypothermia neonates receive sedative, analgesic, anti-epileptic and antibiotic drugs. So far little information is available how the pharmacokinetics (PK) and pharmacodynamics (PD) of these drugs are influenced by post resuscitation multi organ failure and the metabolic effects of the cooling treatment itself. As a result, evidence based dosing guidelines are lacking. This multicenter observational cohort study was designed to answer the question how hypothermia influences the distribution, metabolism and elimination of commonly used drugs in neonatal intensive care. Methods/Design Multicenter cohort study. All term neonates treated with hypothermia for Hypoxic Ischemic Encephalopathy (HIE) resulting from perinatal asphyxia in all ten Dutch Neonatal Intensive Care Units (NICUs) will be eligible for this study. During hypothermia and rewarming blood samples will be taken from indwelling catheters to investigate blood concentrations of several antibiotics, analgesics, sedatives and anti-epileptic drugs. For each individual drug the population PK will be characterized using Nonlinear Mixed Effects Modelling (NONMEM). It will be investigated how clearance and volume of distribution are influenced by hypothermia also taking maturation of neonate into account. Similarly, integrated PK-PD models will be developed relating the time course of drug concentration to pharmacodynamic parameters such as successful seizure treatment; pain assessment and infection clearance. Discussion On basis of the derived population PK-PD models dosing guidelines will be developed for the application of drugs during neonatal hypothermia treatment. The results of this study will lead to an evidence based drug treatment of hypothermic neonatal patients. Results will be published in a national web based evidence based paediatric formulary, peer reviewed journals and international paediatric drug references. Trial registration NTR2529.
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Affiliation(s)
- Timo R de Haan
- Department of Neonatology, Emma Children's Hospital, Academic Medical Center, Amsterdam, The Netherlands.
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Empey PE, Miller TM, Philbrick AH, Melick JA, Kochanek PM, Poloyac SM. Mild hypothermia decreases fentanyl and midazolam steady-state clearance in a rat model of cardiac arrest. Crit Care Med 2012; 40:1221-8. [PMID: 22067624 PMCID: PMC3307845 DOI: 10.1097/ccm.0b013e31823779f9] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVES Therapeutic hypothermia is widely employed for neuroprotection after cardiac arrest. However, concern regarding elevated drug concentrations during hypothermia and increased adverse drug reaction risk complicates concurrent pharmacotherapy. Many commonly used medications in critically ill patients rely on the cytochrome P450 3A isoform for their elimination. Therefore, our study objectives were to determine the effect of mild hypothermia on the in vivo pharmacokinetics of fentanyl and midazolam, two clinically relevant cytochrome P450 3A substrates, after cardiac arrest and to investigate the mechanisms of these alterations. DESIGN Prospective, randomized, controlled study. SETTING University research laboratory. SUBJECTS Thirty-two adult male Sprague-Dawley rats. INTERVENTIONS An asphyxial cardiac arrest rat model was used and mild hypothermia (33°C) was induced 1 hr post injury by surface cooling and continued for 10 hrs to mimic the prolonged clinical application of hypothermia accompanied by intensive care interventions. Fentanyl and midazolam were independently administered by intravenous infusion and plasma and brain concentrations were analyzed using ultraperformance liquid chromatography tandem mass spectrometry. Cytochrome P450 3a2 protein expression was measured and a Michaelis-Menten enzyme kinetic analysis was performed at 37°C and 33°C using control rat microsomes. MEASUREMENTS AND MAIN RESULTS Mild hypothermia decreased the systemic clearance of both fentanyl (61.5 ± 11.5 to 48.9 ± 8.95 mL/min/kg; p < .05) and midazolam (89.2 ± 12.5 to 73.6 ± 12.1 mL/min/kg; p < .05) after cardiac arrest. The elevated systemic concentrations did not lead to parallel increased brain exposures of either drug. Mechanistically, no differences in cytochrome P450 3a2 expression was observed, but the in vitro metabolism of both drugs was decreased at 33°C vs. 37°C through reductions in enzyme metabolic capacity rather than substrate affinity. CONCLUSIONS Mild hypothermia reduces the systemic clearances of fentanyl and midazolam in rats after cardiac arrest through alterations in cytochrome P450 3a2 metabolic capacity rather than enzyme affinity as observed with other cytochrome P450s. Contrasting effects on blood and brain levels further complicates drug dosing. Consideration of the impact of hypothermia on medications whose clearance is dependent on P450 3A metabolism is warranted.
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Affiliation(s)
- Philip E Empey
- Department of Pharmacy and Therapeutics, School of Medicine, Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, USA
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Abstract
Infection is common in the critically ill and often results due to the severity of the patient's illness. Recent data suggest 51% of intensive care unit (ICU) patients are infected, and 71% receive antimicrobial therapy. Bacterial infection is the primary concern, although some fungal infections are opportunistic. Infection more than doubles the ICU mortality rate, and the costs associated with infection may be as high as 40% of total ICU expenditures. There are many contemporary antimicrobial resistance concerns that the critical care clinician must consider in managing the pharmacotherapy of infection. Methicillin resistance in Staphylococcus aureus, vancomycin resistance in Enterococci, beta-lactamase resistance in Enterobacteriaceae, multidrug resistance in Pseudomonas aeruginosa and Acinetobacter species, fluoroquinolone resistance in Escherichia coli, and fungal resistance are among the most common issues ICU clinician's must face in managing infection. Critical illness causes changes in pharmacokinetics that influence drug and dosing considerations. Absorption, distribution, metabolism, and excretion may all be affected by the various disease states that define critical illness. Several specific diseases are discussed, including ventilator-associated pneumonia, various fungal infections, gastrointestinal infections due to Clostridium difficile, urinary tract infections, and bloodstream infections. Within each disease section, discussion includes causes and prevention strategies, microbiology, evidence-based guidelines, and important caveats.
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Affiliation(s)
- Steven J Martin
- Department of Pharmacy Practice, College of Pharmacy, The University of Toledo, Toledo, OH 43606, USA.
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Miyamoto H, Miyake H, Yoshikawa N, Hirata H, Ohwaki Y, Fumoto S, Sasaki H, Nakamura J, Nishida K. Evaluation of changes in hepatic disposition of phenolsulfonphthalein, indocyanine green and fluorescein isothiocyanate-dextran at low temperatures using a rat liver perfusion system†. J Pharm Pharmacol 2012; 64:848-54. [DOI: 10.1111/j.2042-7158.2012.01478.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Abstract
Objectives
The aim of this study was to determine the factor changing the hepatic disposition of a drug during hypothermia using a rat liver perfusion system.
Methods
The livers of male Wistar rats were perfused at 37, 32 or 28°C in the single-pass mode. Venous outflow dilution patterns and biliary excretion rate patterns of phenolsulfonphthalein (PSP), indocyanine green (ICG) and fluorescein isothiocyanate (FITC)-dextran (FD-4, MW 4400) after the injection of a bolus into the perfused rat liver were analysed based on statistical moment theory.
Key findings
The first-pass extraction ratio (Eh) of PSP was significantly decreased at 32 and 28°C compared with 37°C. The biliary recovery of PSP and its conjugate was decreased and the biliary excretion was kept at a high concentration and was prolonged by low perfusion temperatures. ICG was almost extracted by a single-pass through the liver even at 32 and 28°C. The biliary recovery of ICG was significantly decreased at low temperature. Although the distribution volume of FD-4 as a vascular reference was not changed by perfusion temperature, the Eh of FD-4 was decreased at 28°C although not markedly.
Conclusion
The change in hepatic disposition of a drug at low perfusion temperatures differed according to disposition processes under hypothermia.
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Affiliation(s)
- Hirotaka Miyamoto
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Hideaki Miyake
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Naoki Yoshikawa
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Haruna Hirata
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Yuichi Ohwaki
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Shintaro Fumoto
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Hitoshi Sasaki
- Department of Hospital Pharmacy, Nagasaki University Hospital, Nagasaki, Japan
| | - Junzo Nakamura
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Koyo Nishida
- Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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Zhou J, Empey PE, Bies RR, Kochanek PM, Poloyac SM. Cardiac arrest and therapeutic hypothermia decrease isoform-specific cytochrome P450 drug metabolism. Drug Metab Dispos 2011; 39:2209-18. [PMID: 21868471 DOI: 10.1124/dmd.111.040642] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mild therapeutic hypothermia is emerging clinically as a neuroprotection therapy for individuals experiencing cardiac arrest (CA); however, its effects combined with disease pathogenesis on drug disposition and response have not been fully elucidated. We determined the activities of four major hepatic-metabolizing enzymes (CYP3A, CYP2C, CYP2D, and CYP2E) during hypothermia after experimental CA in rats by evaluating the pharmacokinetics of their probe drugs as a function of altered body temperature. Animals were randomized into sham normothermia (37.5-38°C), CA normothermia, sham hypothermia (32.5-33°C), and CA hypothermia groups. Probe drugs (midazolam, diclofenac, dextromethorphan, and chlorzoxazone) were given simultaneously by intravenous bolus after temperature stabilization. Multiple blood samples were collected between 0 and 8 h after drug administration. Pharmacokinetic (PK) analysis was conducted using a noncompartmental approach and population PK modeling. Noncompartmental analysis showed that the clearance of midazolam (CYP3A) in CA hypothermia was reduced from sham normothermia rats (681.6 ± 190.0 versus 1268.8 ± 348.9 ml · h(-1) · kg(-1), p < 0.05). The clearance of chlorzoxazone (CYP2E) in CA hypothermia was also reduced from sham normothermia rats (229.6 ± 75.6 versus 561.89 ± 215.9 ml · h(-1) · kg(-1), p < 0.05). Population PK analysis further demonstrated the decreased clearance of midazolam (CYP3A) was associated with CA injury (p < 0.05). The decreased clearance of chlorzoxazone (CYP2E1) was also associated with CA injury (p < 0.01). Hypothermia was found to be associated with the decreased volume of distribution of midazolam (V(1)), dextromethorphan (V(1)), and peripheral compartment for chlorzoxazone (V(2)) (p < 0.05, p < 0.05, and p < 0.01, respectively). Our data indicate that hypothermia, CA, and their interaction alter cytochrome P450-isoform specific activities in an isoform-specific manner.
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Affiliation(s)
- Jiangquan Zhou
- Department of Pharmaceutical Sciences, University of Pittsburgh School of Pharmacy, Pittsburgh, PA 15261, USA
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Abstract
With mounting evidence that hypothermia is neuroprotective in newborns with hypoxic-ischemic encephalopathy (HIE), an increasing number of centers are offering this therapy. Hypothermia is associated with a wide range of physiologic changes affecting every organ system, and awareness of these effects is essential for optimum patient management. Lowering the core temperature also alters pharmacokinetic and pharmacodynamic properties of medications commonly used in asphyxiated neonates, necessitating close attention to drug efficacy and side effects. Rewarming introduces additional risks and challenges as the hypothermia-associated physiologic and pharmacologic changes are reversed. In this review we provide an organ system-based assessment of physiologic changes associated with hypothermia. We also summarize evidence from randomized controlled trials showing lack of serious adverse effects of moderate hypothermia therapy in term and near-term newborns with moderate-to-severe HIE. Finally, we review the effects of hypothermia on drug metabolism and clearance based on studies in animal models and human adults, and limited data from neonates.
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Affiliation(s)
- S Zanelli
- Department of Pediatrics, University of Virginia, Charlottesville, USA.
| | - M Buck
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA,Department of Pharmacy, University of Virginia, Charlottesville, VA, USA
| | - K Fairchild
- Department of Pediatrics, University of Virginia, Charlottesville, VA, USA
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Abstract
Therapeutic hypothermia is becoming an important intervention following acute neurologic injury despite inconclusive results concerning efficacy. This enthusiasm primarily stems from a lack of other effective interventions in this population. With the increase in the use of therapeutic hypothermia, several practical issues must be considered when initiating this intervention. Clinical pharmacists can play an important role in anticipating and addressing some complications such as shivering, slow drug metabolism, and infection. This review will discuss the available literature concerning the efficacy of therapeutic hypothermia in various neurologic injuries, as well as the most common adverse events associated with it.
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Affiliation(s)
- Xi Liu-DeRyke
- Department of Pharmacy, Orlando Regional Medical Center, Orlando, FL 32806, USA.
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Zhou J, Poloyac SM. The effect of therapeutic hypothermia on drug metabolism and response: cellular mechanisms to organ function. Expert Opin Drug Metab Toxicol 2011; 7:803-16. [PMID: 21473710 DOI: 10.1517/17425255.2011.574127] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION Therapeutic hypothermia is being employed clinically due to its neuro-protective benefits. Both critical illness and therapeutic hypothermia significantly affect drug disposition, potentially contributing to drug-therapy and drug-disease interactions. Currently, there is limited information on the known alterations in drug concentration and response during mild hypothermia treatment, and there is a limited understanding of the specific mechanisms that underlie alterations in drug concentrations and the potential clinical importance of these changes. AREAS COVERED A systemic review of the effect of therapeutic hypothermia on drug metabolism, disposition and response is provided. Specifically, the clinical and preclinical evidence of the effects of therapeutic hypothermia on blood flow, specific hepatic metabolism pathways, transporter function, renal excretion, pharmacodynamics and the effects during rewarming are reviewed. EXPERT OPINION Available evidence demonstrates that mild hypothermia decreases the clearance of a variety of drugs with apparently little change in drug-protein binding. Recent evidence suggests that the magnitude of the change is elimination route specific. Further research is needed to determine the impact of these alterations on both drug concentration and response in order to optimize the therapeutic hypothermia in this vulnerable patient population.
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Affiliation(s)
- Jiangquan Zhou
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, 3501 Terrace Street, Pittsburgh, PA 15261, USA
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32
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&NA;. Dosages of some drugs may need to be adjusted in patients undergoing therapeutic hypothermia. Drugs & Therapy Perspectives 2011. [DOI: 10.2165/11206670-000000000-00000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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Dearing N, Norgard NB. Rhabdomyolysis in a Patient Receiving High-Dose Simvastatin After the Induction of Therapeutic Hypothermia. Ann Pharmacother 2010; 44:1994-7. [DOI: 10.1345/aph.1p352] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Objective: To report a case of rhabdomyolysis in a patient receiving high-dose simvastatin after the induction of therapeutic hypothermia. Case Summary: A 45-year-old African American male was brought to the emergency department for a witnessed cardiac arrest. He was placed on a therapeutic hypothermia protocol and his simvastatin dose was increased from 40 to 80 mg at bedtime. Target core temperature (34 °C) was reached within 8 hours and was maintained for 24 hours. His admission creatine kinase was 965 units/L, which decreased to 153 units/L by day 4. On day 5, the patient voided a large quantity of orange-brown urine and had a dramatically increased creatine kinase (8523 unit/L) level and myoglobinuria. Statin therapy was subsequently discontinued. Creatine kinase remained elevated for 2 days, then gradually declined toward normal levels over the following week. Discussion: Simvastatin undergoes extensive first-pass metabolism mediated by CYP3A4, making it susceptible to significant drug interactions. Therapeutic hypothermia has been shown to significantly reduce the clearance of CYP3A4 substrates. We attribute this patient's rhabdomyolysis to a therapy-drug interaction between the therapeutic hypothermia and the administration of high-dose simvastatin. We believe that the induced hypothermia caused a reduction in simvastatin clearance, leading to toxic plasma concentrations. According to the Naranjo probability scale, it was probable that the rhabdomyolysis was related to simvastatin use. The Horn Drug Interaction Probability Scale likewise classified the probability of a causal relationship between the potential therapy-drug interaction and the event as probable. Conclusions: Clinicians must be aware of the pharmacokinetic effects of therapeutic hypothermia to prevent potential drug-therapy interactions. It may be prudent to avoid the use of CYP3A4 substrates that are not essential treatments in patients undergoing therapeutic hypothermia until more information is known about their safety in this patient population.
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Affiliation(s)
- Natalie Dearing
- Department of Pharmacy Practice and Administration, School of Pharmacy, Saint Joseph College, Hartford, CT
| | - Nicholas B Norgard
- Cardiology, School of Pharmacy and Pharmaceutical Sciences, University at Buffalo, Buffalo, NY
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Hostler D, Zhou J, Tortorici MA, Bies RR, Rittenberger JC, Empey PE, Kochanek PM, Callaway CW, Poloyac SM. Mild hypothermia alters midazolam pharmacokinetics in normal healthy volunteers. Drug Metab Dispos 2010; 38:781-8. [PMID: 20164112 DOI: 10.1124/dmd.109.031377] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The clinical use of therapeutic hypothermia has been rapidly expanding due to evidence of neuroprotection. However, the effect of hypothermia on specific pathways of drug elimination in humans is relatively unknown. To gain insight into the potential effects of hypothermia on drug metabolism and disposition, we evaluated the pharmacokinetics of midazolam as a probe for CYP3A4/5 activity during mild hypothermia in human volunteers. A second objective of this work was to determine whether benzodiazepines and magnesium administered intravenously would facilitate the induction of hypothermia. Subjects were enrolled in a randomized crossover study, which included two mild hypothermia groups (4 degrees C saline infusions and 4 degrees C saline + magnesium) and two normothermia groups (37 degrees C saline infusions and 37 degrees C saline + magnesium). The lowest temperatures achieved in the 4 degrees C saline + magnesium and 4 degrees C saline infusions were 35.4 +/- 0.4 and 35.8 +/- 0.3 degrees C, respectively. A significant decrease in the formation clearance of the major metabolite 1'-hydroxymidazolam was observed during the 4 degrees C saline + magnesium compared with that in the 37 degrees C saline group (p < 0.05). Population pharmacokinetic modeling identified a significant relationship between temperature and clearance and intercompartmental clearance for midazolam. This model predicted that midazolam clearance decreases 11.1% for each degree Celsius reduction in core temperature from 36.5 degrees C. Midazolam with magnesium facilitated the induction of hypothermia, but shivering was minimally suppressed. These data provided proof of concept that even mild and short-duration changes in body temperature significantly affect midazolam metabolism. Future studies in patients who receive lower levels and a longer duration of hypothermia are warranted.
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Affiliation(s)
- David Hostler
- Department of Emergency Medicine, Emergency Responder Human Performance Laboratory, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA
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Zanelli S, Fairchild K. Physiologic and Pharmacologic Effects of Therapeutic Hypothermia for Neonatal Hypoxic Ischemic Encephalopathy. ACTA ACUST UNITED AC 2009. [DOI: 10.1053/j.nainr.2008.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Tortorici MA, Mu Y, Kochanek PM, Xie W, Poloyac SM. Moderate hypothermia prevents cardiac arrest-mediated suppression of drug metabolism and induction of interleukin-6 in rats. Crit Care Med 2009; 37:263-9. [PMID: 19050605 DOI: 10.1097/CCM.0b013e3181931ed3] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
OBJECTIVE Therapeutic hypothermia is being clinically used to reduce neurologic deficits after cardiac arrest (CA). Patients receiving hypothermia after CA receive a wide-array of medications. During hypothermia, drug metabolism is markedly reduced. Little, however, is known about the impact of hypothermia on drug metabolism after rewarming. The objective of this study was to examine the effect of CA and hypothermia on the functional regulation of two major drug metabolizing cytochrome P450 (CYP) isoforms. DESIGN Laboratory investigation. SETTING University pharmacy school and animal research facility. SUBJECTS Thirty-six male Sprague-Dawley rats. INTERVENTIONS Hypothermia was induced via surface cooling in a rat CA model and maintained for 3 hrs. Animals were killed at 5 or 24 hrs and liver was analyzed for hepatic activity and mRNA expression of CYP3A2 and CYP2E1. Plasma interleukin-6 (IL-6) concentrations were determined. The effect of IL-6 on pregnane X receptor-mediated transcription of the rat CYP3A2 promoter was evaluated via luciferase reporter in HepG2 cells. MEASUREMENTS AND MAIN RESULTS At 24 hrs after CA a decrease in CYP3A2 and CYP2E1 activity was observed, 55.7% +/- 12.8% and 46.8% +/- 29.7% of control, respectively (p < 0.01). CA decreased CYP3A2 mRNA (p < 0.05), but not CYP2E1 mRNA. Expression of other pregnane X receptor target enzymes and transporter genes were similarly down-regulated. CA also produced an approximately ten-fold increase in plasma IL-6. CA-mediated inhibition of CYP3A2 and CYP2E1 was attenuated by hypothermia, as was the increase in IL-6. Furthermore, IL-6 attenuated pregnane X receptor-mediated transcription of the CYP3A2 promoter. CONCLUSIONS CA produces CYP3A2 down-regulation at 24 hrs, potentially via IL-6 effects on pregnane X receptor-mediated transcription. Also, hypothermia attenuates the CA-mediated down-regulation, thereby normalizing drug metabolism after rewarming.
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Abstract
Abstract Therapeutic hypothermia has emerged as an effective means of improving neurologic outcomes among cardiac arrest survivors. To achieve optimal results, clinicians must understand and anticipate potential adverse effects of cooling and provide rigorous monitoring and/or pharmacologic interventions as appropriate. Using pharmacotherapy to counter adverse effects of cooling or to treat an intrinsic process under hypothermic conditions requires understanding how hypothermia will influence the clinical effects of the drug, including the drug's pharmacokinetics and pharmacodynamics. The pharmacologic aspects of therapeutic hypothermia in relation to physiology and adverse effects are reviewed.
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Affiliation(s)
- Paul A Arpino
- Department of Pharmacy, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
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Róka A, Melinda KT, Vásárhelyi B, Machay T, Azzopardi D, Szabó M. Elevated morphine concentrations in neonates treated with morphine and prolonged hypothermia for hypoxic ischemic encephalopathy. Pediatrics 2008; 121:e844-9. [PMID: 18381513 DOI: 10.1542/peds.2007-1987] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVES Asphyxia and hypothermia may modify drug pharmacokinetics. We investigated whether analgesia with morphine in neonates with hypoxic ischemic encephalopathy undergoing prolonged moderate systemic hypothermia resulted in elevated serum morphine concentrations compared with normothermic infants. PATIENTS AND METHODS Infants from 1 center participating in a multicenter randomized study of moderate whole-body hypothermia after perinatal asphyxia (the Total Body Hypothermia Study) were randomly selected for treatment with hypothermia (n = 10) or for standard care on normothermia (n = 6). Hypothermia (33 degrees C to 34 degrees C) was started before 6 hours of age and maintained for 72 hours. All of the infants were treated with a continuous infusion of morphine-hydrochloride, with the rate adjusted according to clinical status. Serum morphine concentrations were determined at 6, 12, 24, 48, and 72 hours after birth. RESULTS Serum morphine concentrations at 24 to 72 hours after birth were (median [range]) 292 ng/mL (137-767 ng/mL) in the hypothermia-treated infants and 206 ng/mL (88-327 ng/mL) in the infants on normothermia, despite similar morphine infusion rates and cumulative doses. Morphine concentrations correlated with morphine infusion rate, cumulative dose, and treatment with hypothermia. Serum morphine concentrations reached a steady state after 24 hours in the normothermic infants but continued to increase throughout the assessment period in the hypothermia group. Morphine clearance was low in both groups: (median [range]) morphine clearance estimated from area under the curve was 0.69 mL/min per kg (0.58-1.21 mL/min per kg) in hypothermic group and 0.89 mL/min per kg (0.65-1.33 mL/min per kg) in infants on normothermia. Serum morphine concentrations >300 nL/mL occurred more often in the hypothermia group and when the morphine infusion rate was >10 microg/kg per h. CONCLUSIONS Infants with hypoxic ischemic encephalopathy have reduced morphine clearance and elevated serum morphine concentrations when morphine infusion rates are based on clinical state. Potentially toxic serum concentrations of morphine may occur with moderate hypothermia and infusion rates >10 microg/kg per h.
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Affiliation(s)
- Anikó Róka
- First Department of Paediatrics, Semmelweis University, 1083 Budapest Bókay Str 53, Hungary.
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Nishida K, Okazaki M, Sakamoto R, Inaoka N, Miyake H, Fumoto S, Nakamura J, Nakashima M, Sasaki H, Kakumoto M, Sakaeda T. Change in pharmacokinetics of model compounds with different elimination processes in rats during hypothermia. Biol Pharm Bull 2007; 30:1763-7. [PMID: 17827736 DOI: 10.1248/bpb.30.1763] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We compared the pharmacokinetics of model compounds with different elimination processes between hypothermic and normothermic rats, to obtain basic information concerning drug therapy during hypothermia. Male Wistar rats were anesthetized with sodium pentobarbital and kept at temperatures of 37 degrees C (normothermic group) by heat lamp, and 32 degrees C or 28 degrees C (hypothermic group) by external cooling. We chose phenolsulfonphthalein (PSP), indocyanine green (ICG) and fluorescein isothiocyanate (FITC)-dextran (FD-4, Mw 4400) as model compounds to determine changes in clearance pathways during hypothermia therapy. The plasma concentrations of PSP as biliary, urinary and metabolic elimination type were increased significantly in the hypothermic group (32 degrees C, 28 degrees C) after i.v. administration at a dose of 1 mg, compared to the normothermic group (37 degrees C). Each PSP clearance (bile, urine and metabolites) in the hypothermic group was decreased, suggesting an influence of hypothermia on the active elimination process. The decreasing tendency was marked at a temperature of 28 degrees C. Moreover, the plasma concentrations of ICG as the biliary excretion type after i.v. administration to the hypothermic rats at a dose of 1 mg were higher with more than 50% decrease in the total body clearance compared to normothermic rats. On the other hand, there was almost no difference in the i.v. pharmacokinetics of FD-4 as the urinary excretion type between 37 degrees C and 32 degrees C. However, renal clearance of FD-4 was significantly decreased at a temperature of 28 degrees C. Accordingly, the change in pharmacokinetics of a drug in the hypothermic group could differ with the elimination processes.
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Affiliation(s)
- Koyo Nishida
- Department of Clinical Pharmacy, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki 852-8521, Japan.
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Tortorici MA, Kochanek PM, Poloyac SM. Effects of hypothermia on drug disposition, metabolism, and response: A focus of hypothermia-mediated alterations on the cytochrome P450 enzyme system. Crit Care Med 2007; 35:2196-204. [PMID: 17855837 DOI: 10.1097/01.ccm.0000281517.97507.6e] [Citation(s) in RCA: 291] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
OBJECTIVES Therapeutic hypothermia has been shown to decrease neurologic damage in patients experiencing out-of-hospital cardiac arrest. In addition to being treated with hypothermia, critically ill patients are treated with an extensive pharmacotherapeutic regimen. The effects of hypothermia on drug disposition increase the probability for unanticipated toxicity, which could limit its putative benefit. This review examines the effects of therapeutic hypothermia on the disposition, metabolism, and response of drugs commonly used in the intensive care unit, with a focus on the cytochrome P450 enzyme system. DATA SOURCES AND STUDY SELECTION A MEDLINE/PubMed search from 1965 to June 2006 was conducted using the search terms hypothermia, drug metabolism, P450, critical care, cardiac arrest, traumatic brain injury, and pharmacokinetics. DATA EXTRACTION AND SYNTHESIS Twenty-one studies were included in this review. The effects of therapeutic hypothermia on drug disposition include both the effects during cooling and the effects after rewarming on drug metabolism and response. The studies cited in this review demonstrate that the addition of mild to moderate hypothermia decreases the systemic clearance of cytochrome P450 metabolized drugs between approximately 7% and 22% per degree Celsius below 37degreesC during cooling. The addition of hypothermia decreases the potency and efficacy of certain drugs. CONCLUSIONS This review provides evidence that the therapeutic index of drugs is narrowed during hypothermia. The magnitude of these alterations indicates that intensivists must be aware of these alterations in order to maximize the therapeutic efficacy of this modality. In addition to increased clinical attention, future research efforts are essential to delineate precise dosing guidelines and mechanisms of the effect of hypothermia on drug disposition and response.
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Affiliation(s)
- Michael A Tortorici
- University of Pittsburgh School of Pharmacy, Department of Pharmaceutical Sciences, Pittsburgh, PA, USA
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Abstract
A male neonate with a Chiari malformation and a leaking myelomeningocoele underwent ventriculoperitoneal shunt insertion followed by repair of myelomeningocoele. During anaesthesia and surgery, he inadvertently became moderately hypothermic. Intravenous phenytoin was administered during the later part of the surgery for seizure prophylaxis. Following phenytoin administration, the patient developed acute severe bradycardia, refractory to atropine and adrenaline. The cardiac depressant actions of phenytoin and hypothermia can be additive. Administration of phenytoin in the presence of hypothermia may lead to an adverse cardiac event in children. As phenytoin is a commonly used drug, clinicians need to be aware of this interaction.
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Affiliation(s)
- Hemant Bhagat
- Department of Neuroanaesthesiology, Neurosciences Centre, Room No. 709-A, C.N. Centre, All India Institute of Medical Sciences, New Delhi 110029, India.
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Tortorici MA, Kochanek PM, Bies RR, Poloyac SM. Therapeutic hypothermia-induced pharmacokinetic alterations on CYP2E1 chlorzoxazone-mediated metabolism in a cardiac arrest rat model*. Crit Care Med 2006; 34:785-91. [PMID: 16521272 DOI: 10.1097/01.ccm.0000201899.52739.4f] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVES Therapeutic hypothermia has demonstrated considerable benefit in patients experiencing cardiac arrest. Despite increasing clinical use, there is a paucity of information regarding the effect of hypothermia on the disposition of medications, specifically cytochrome P450-mediated drug metabolism. The objective was to determine the effect of hypothermia after cardiac arrest on the in vivo kinetics of a cytochrome P450 (CYP2E1) probe drug, chlorzoxazone, and to investigate the mechanism of these alterations. DESIGN Laboratory investigation. SETTING University pharmacy school and animal research facility. SUBJECTS Sixteen male Sprague-Dawley rats. INTERVENTIONS An asphyxial arrest rat model was used and moderate hypothermia was induced immediately postinsult via surface cooling. Chlorzoxazone was administered as an intravenous bolus, and plasma concentrations were analyzed using high-performance liquid chromatography methods. Protein binding was analyzed using rat control plasma, and Michaelis-Menten enzyme kinetic analysis was performed at 37 degrees C and 30 degrees C using control rat microsomes at varying concentrations of chlorzoxazone. MEASUREMENTS AND MAIN RESULTS Moderate hypothermia after cardiac arrest in rats markedly decreased the systemic clearance of the CYP2E1 substrate, chlorzoxazone, when compared with normothermia after cardiac arrest, 1.26+/-0.34 mL/min vs. 0.580+/-0.37 mL/min (p<.001). No changes in chlorzoxazone protein binding were observed at 37 degrees C and 30 degrees C, and CYP2E1 enzyme capacity (maximum velocity) was not altered at these different incubation temperatures. However, Michaelis-Menten constant was significantly increased at 30 degrees C (551+/-150 microM) compared with incubations at 37 degrees C (255+/-52 microM, p<.01). CONCLUSIONS Moderate hypothermia markedly reduces the systemic clearance of chlorzoxazone in cardiac arrest rats. This results from hypothermia-induced decreases in the CYP2E1 enzyme affinity for the substrate chlorzoxazone. This is the first systematic mechanistic investigation of the effect of hypothermia on CYP2E1-mediated metabolism.
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Affiliation(s)
- Michael A Tortorici
- University of Pittsburgh School of Pharmacy, Department of Pharmaceutical Sciences, and Department of Paediatrics, the Children't Hospital of Pittsburgh, PA, USA
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Jin JS, Sakaeda T, Kakumoto M, Nishiguchi K, Nakamura T, Okamura N, Okumura K. Effect of Therapeutic Moderate Hypothermia on Multi-drug Resistance Protein 1-Mediated Transepithelial Transport of Drugs. Neurol Med Chir (Tokyo) 2006; 46:321-7; discussion 327. [PMID: 16861824 DOI: 10.2176/nmc.46.321] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
To clarify the effect of therapeutic moderate hypothermia on drug distribution, transepithelial transport via multi-drug resistance protein 1 (MDR1) (also called P-glycoprotein or ABCB1) was evaluated at various temperatures in vitro using LLC-GA5-COL150 cells, which were established by transfecting human MDR1 complementary deoxyribonucleic acid into kidney epithelial LLC-PK(1) cells and express MDR1 on the apical membrane. MDR1 is expressed in the blood-brain barrier to limit drug distribution to the brain by exporting exogenous substances including calcium blockers and antiarrhythmic drugs. Digoxin was used as a typical substrate, as well as the non-substrate tetracycline and paracellular marker inulin. MDR1-mediated transport of digoxin decreased at lower temperatures. Transport of tetracycline also decreased at lower temperatures, probably due to changes in membrane fluidity. However, no change was found at over 32 degrees C, suggesting that passive diffusion does not change during moderate hypothermia. The distribution of MDR1 substrates should be considered during hypothermic conditions, as the clinical outcome could be affected.
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Affiliation(s)
- Jiang-shu Jin
- Department of Hospital Pharmacy, School of Medicine, Kobe University, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan
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Fritz HG, Holzmayr M, Walter B, Moeritz KU, Lupp A, Bauer R. The Effect of Mild Hypothermia on Plasma Fentanyl Concentration and Biotransformation in Juvenile Pigs. Anesth Analg 2005; 100:996-1002. [PMID: 15781513 DOI: 10.1213/01.ane.0000146517.17910.54] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Therapeutic hypothermia may alter the required dosage of analgesics and sedatives, but no data are available on the effects of mild hypothermia on plasma fentanyl concentration during continuous, long-term administration. We therefore assessed in a porcine model the effect of prolonged hypothermia on plasma fentanyl concentration during 33 h of continuous fentanyl administration. Seven female piglets (weight: 11.8 +/- 1.1 kg) were anesthetized by IV fentanyl (15 microg . kg(-1) . h(-1)) and midazolam (1.0 mg . kg(-1) . h(-1)). After preparation and stabilization (12 h), the animals were cooled to a core temperature of 31.6 degrees +/- 0.2 degrees C for 6 h and were then rewarmed and kept normothermic at 37.7 degrees +/- 0.3 degrees C for 6 more hours. Plasma fentanyl concentrations were measured by radioimmunoassay, cardiac index by thermodilution, and blood flows of the kidney, spleen, pancreas, stomach, gut, and hepatic artery by a colored microspheres technique. Furthermore, in an additional 4 pigs, temperature dependency of hepatic microsomal cytochrome P450 3A4 (CYP3A4) was determined in vitro by ethylmorphine N-demethylation. Plasma fentanyl concentration increased by 25% +/- 11% (P < 0.05) during hypothermia and remained increased for at least 6 h after rewarming. Hypothermia reduced the cardiac index (41% +/- 15%, P < 0.05), as well as all organ blood flows except the hepatic artery. A strong temperature dependency of CYP3A4 was found (P < 0.01). Mild hypothermia induced a distribution and/or elimination-dependent increase in plasma fentanyl concentration which remained increased for several hours after rewarming. Consequently, a prolonged increase of the plasma fentanyl concentration should be anticipated for appropriate control of the analgesia/sedatives during and early after therapeutic hypothermia.
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Affiliation(s)
- Harald G Fritz
- Departments of *Anesthesiology and Intensive Care Medicine and †Pathobiochemistry, Institute for Pathophysiology and Pathobiochemistry, ‡Department of Neurosurgery and §Institute for Pharmacology and Toxicology, Friedrich-Schiller-University, Jena; and ∥ Institute of Pharmacology, Ernst Moritz Arndt University, Greifswald, Germany
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