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Therapeutic hypothermia decreases phenytoin elimination in children with traumatic brain injury.

ABSTRACT: 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.Pharmacokinetic analysis of subjects participating in a multicenter randomized phase III study of therapeutic hypothermia for severe traumatic brain injury.ICU at the Children's Hospital of Pittsburgh.Nineteen children with severe traumatic brain injury.None.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.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.

SUBMITTER: Empey PE

PROVIDER: S-EPMC3783553 | biostudies-literature | 2013 Oct

REPOSITORIES: biostudies-literature

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Therapeutic hypothermia decreases phenytoin elimination in children with traumatic brain injury.

Empey Philip E PE Velez de Mendizabal Nieves N Bell Michael J MJ Bies Robert R RR Anderson Kacey B KB Kochanek Patrick M PM Adelson P David PD Poloyac Samuel M SM

Critical care medicine 20131001 10

<h4>Objective</h4>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 th ...[more]

PMID: 23896831

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Project description:BACKGROUND:Hypothermia has been used in the treatment of brain injury for many years. Encouraging results from small trials and laboratory studies led to renewed interest in the area and some larger trials. OBJECTIVES:To determine the effect of mild hypothermia for traumatic brain injury (TBI) on mortality, long-term functional outcomes and complications. SEARCH METHODS:We ran and incorporated studies from database searches to 21 March 2016. We searched the Cochrane Injuries Group's Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library), MEDLINE (OvidSP), Embase Classic+Embase (OvidSP), PubMed, ISI Web of science (SCI-EXPANDED, SSCI, CPCI-S & CPSI-SSH), clinical trials registers, and screened reference lists. We also re-ran these searches pre-publication in June 2017; the result from this search is presented in 'Studies awaiting classification'. SELECTION CRITERIA:We included randomised controlled trials of participants with closed TBI requiring hospitalisation who were treated with hypothermia to a maximum of 35 ºC for at least 12 consecutive hours. Treatment with hypothermia was compared to maintenance with normothermia (36.5 to 38 ºC). DATA COLLECTION AND ANALYSIS:Two review authors assessed data on mortality, unfavourable outcomes according to the Glasgow Outcome Scale, and pneumonia. MAIN RESULTS:We included 37 eligible trials with a total of 3110 randomised participants; nine of these were new studies since the last update (2009) and five studies had been previously excluded but were re-assessed and included during the 2017 update. We identified two ongoing studies from searches of clinical trials registers and database searches and two studies await classification.Studies included both adults and children with TBI. Most studies commenced treatment immediately on admission to hospital or after craniotomies and all treatment was maintained for at least 24 hours. Thirty-three studies reported data for mortality, 31 studies reported data for unfavourable outcomes (death, vegetative state or severe disability), and 14 studies reported pneumonia. Visual inspection of the results for these outcomes showed inconsistencies among studies, with differences in the direction of effect, and we did not pool these data for meta-analysis. We considered duration of hypothermia therapy and the length of follow-up in collected data for these subgroups; differences in study data remained such that we did not perform meta-analysis.Studies were generally poorly reported and we were unable to assess risk of bias adequately. Heterogeneity was evident both in the trial designs and participant inclusion. Inconsistencies in results may be explained by heterogeneity among study participants or bias introduced by individual study methodology but we did not explore this in detail in subgroup or sensitivity analyses. We used the GRADE approach to judge the quality of the evidence for each outcome and downgraded the evidence for mortality and unfavourable outcome to very low. We downgraded the evidence for the pneumonia outcome to low. AUTHORS' CONCLUSIONS:Despite a large number studies, there remains no high-quality evidence that hypothermia is beneficial in the treatment of people with TBI. Further research, which is methodologically robust, is required in this field to establish the effect of hypothermia for people with TBI.

Project description:Preclinical and clinical studies have shown therapeutic potential of mild-to-moderate hypothermia for treatments of stroke and traumatic brain injury (TBI). Physical cooling in humans, however, is usually slow, cumbersome, and necessitates sedation that prevents early application in clinical settings and causes several side effects. Our recent study showed that pharmacologically induced hypothermia (PIH) using a novel neurotensin receptor 1 (NTR1) agonist, HPI-201 (also known as ABS-201), is efficient and effective in inducing therapeutic hypothermia and protecting the brain from ischemic and hemorrhagic stroke in mice. The present investigation tested another second-generation NTR1 agonist, HPI-363, for its hypothermic and protective effect against TBI. Adult male mice were subjected to controlled cortical impact (CCI) (velocity=3?m/sec, depth=1.0?mm, contact time=150?msec) to the exposed cortex. Intraperitoneal administration of HPI-363 (0.3?mg/kg) reduced body temperature by 3-5°C within 30-60?min without triggering a shivering defensive reaction. An additional two injections sustained the hypothermic effect in conscious mice for up to 6?h. This PIH treatment was initiated 15, 60, or 120?min after the onset of TBI, and significantly reduced the contusion volume measured 3 days after TBI. HPI-363 attenuated caspase-3 activation, Bax expression, and TUNEL-positive cells in the pericontusion region. In blood-brain barrier assessments, HPI-363 ameliorated extravasation of Evans blue dye and immunoglobulin G, attenuated the MMP-9 expression, and decreased the number of microglia cells in the post-TBI brain. HPI-363 decreased the mRNA expression of tumor necrosis factor-? and interleukin-1? (IL-1?), but increased IL-6 and IL-10 levels. Compared with TBI control mice, HPI-363 treatments improved sensorimotor functional recovery after TBI. These findings suggest that the second generation NTR-1 agonists, such as HPI-363, are efficient hypothermic-inducing compounds that have a strong potential in the management of TBI.

Project description:IntroductionResearch into therapeutic hypothermia following traumatic brain injury has been characterised by small trials of poor methodological quality, producing variable results. The Cochrane review, published in 2009, now requires updating. The aim of this systematic review is to assess the effectiveness of the application of therapeutic hypothermia to reduce death and disability when administered to adult patients who have been admitted to hospital following traumatic brain injury.MethodsTwo authors extracted data from each trial. Unless stated in the trial report, relative risks and 95% confidence intervals (CIs) were calculated for each trial. We considered P?<?0?·?05 to be statistically significant. We combined data from all trials to estimate the pooled risk ratio (RR) with 95% confidence intervals for death, unfavourable outcome, and pneumonia. All statistical analyses were performed using RevMan 5.1 (Cochrane IMS, Oxford, UK) and Stata (Intercooled Version 12.0, StataCorp LP). Pooled RRs were calculated using the Mantel-Haenszel estimator. The random effects model of DerSimonian and Laird was used to estimate variances for the Mantel-Haenszel and inverse variance estimators.ResultsTwenty studies are included in the review, while 18 provided mortality data. When the results of 18 trials that evaluated mortality as one of the outcomes were statistically aggregated, therapeutic hypothermia was associated with a significant reduction in mortality and a significant reduction in poor outcome. There was a lack of statistical evidence for an association between use of therapeutic hypothermia and increased onset of new pneumonia.ConclusionsIn contrast to previous reviews, this systematic review found some evidence to suggest that therapeutic hypothermia may be of benefit in the treatment of traumatic brain injury. The majority of trials were of low quality, with unclear allocation concealment. Low quality trials may overestimate the effectiveness of hypothermia treatment versus standard care. There remains a need for more, high quality, randomised control trials of therapeutic hypothermia after traumatic brain injury.

Project description:PURPOSE:Therapeutic hypothermia management remains controversial in patients with traumatic brain injury. We conducted a meta-analysis to evaluate the risks and benefits of therapeutic hypothermia management in patients with traumatic brain injury. METHODS:We searched the Web of Science, PubMed, Embase, Cochrane (Central) and Clinical Trials databases from inception to January 17, 2019. Eligible studies were randomised controlled trials that investigated therapeutic hypothermia management versus normothermia management in patients with traumatic brain injury. We collected the individual data of the patients from each included study. Meta-analyses were performed for 6-month mortality, unfavourable functional outcome and pneumonia morbidity. The risk of bias was evaluated using the Cochrane Risk of Bias tool. RESULTS:Twenty-three trials involving a total of 2796 patients were included. The randomised controlled trials with a high quality show significantly more mortality in the therapeutic hypothermia group [risk ratio (RR) 1.26, 95% confidence interval (CI) 1.04 to 1.53, p?=?0.02]. Lower mortality in the therapeutic hypothermia group occurred when therapeutic hypothermia was received within 24?h (RR 0.83, 95% CI 0.71 to 0.96, p?=?0.01), when hypothermia was received for treatment (RR 0.66, 95% CI 0.49 to 0.88, p?=?0.006) or when hypothermia was combined with post-craniectomy measures (RR 0.69, 95% CI 0.48 to 1.00, p?=?0.05). The risk of unfavourable functional outcome following therapeutic hypothermia management appeared to be significantly reduced (RR 0.78, 95% CI 0.67 to 0.91, p?=?0.001). The meta-analysis suggested that there was a significant increase in the risk of pneumonia with therapeutic hypothermia management (RR 1.48, 95% CI 1.11 to 1.97, p?=?0.007). CONCLUSIONS:Our meta-analysis demonstrated that therapeutic hypothermia did not reduce but might increase the mortality rate of patients with traumatic brain injury in some high-quality studies. However, traumatic brain injury patients with elevated intracranial hypertension could benefit from hypothermia in therapeutic management instead of prophylaxis when initiated within 24?h.

Project description:ObjectivesTo identify injury patterns and characteristics associated with severe traumatic brain injury course and outcome, within a well-characterized cohort, which may help guide new research and treatment initiatives.DesignA secondary analysis of a phase 3, randomized, controlled trial that compared therapeutic hypothermia versus normothermia following severe traumatic brain injury in children.SettingFifteen sites in the United States, Australia, and New Zealand.PatientsChildren (< 18 yr old) with severe traumatic brain injury.Measurements and main resultsBaseline, clinical, and CT characteristics of patients (n = 77) were examined for association with mortality and outcome, as measured by the Glasgow Outcome Scale-Extended Pediatric Revision 3 months after traumatic brain injury. Data are presented as odds ratios with 95% CIs. No demographic, clinical, or CT characteristic was associated with mortality in bivariate analysis. Characteristics associated with worse Glasgow Outcome Scale-Extended Pediatric Revision in bivariate analysis were two fixed pupils (14.17 [3.38-59.37]), abdominal Abbreviated Injury Severity score (2.03 [1.19-3.49]), and subarachnoid hemorrhage (3.36 [1.30-8.70]). Forward stepwise regression demonstrated that Abbreviated Injury Severity spine (3.48 [1.14-10.58]) and midline shift on CT (8.35 [1.05-66.59]) were significantly associated with mortality. Number of fixed pupils (one fixed pupil 3.47 [0.79-15.30]; two fixed pupils 13.61 [2.89-64.07]), hypoxia (5.22 [1.02-26.67]), and subarachnoid hemorrhage (3.01 [1.01-9.01]) were independently associated with worse Glasgow Outcome Scale-Extended Pediatric Revision following forward stepwise regression.ConclusionsSevere traumatic brain injury is a clinically heterogeneous disease that can be accompanied by a range of neurologic impairment and a variety of injury patterns at presentation. This secondary analysis of prospectively collected data identifies several characteristics associated with outcome among children with severe traumatic brain injury. Future, larger trials are needed to better characterize phenotypes within this population.

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Therapeutic hypothermia decreases phenytoin elimination in children with traumatic brain injury.

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Therapeutic hypothermia decreases phenytoin elimination in children with traumatic brain injury.

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