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Management of critically ill patients requires simultaneous administration of many medications. Treatment for patient comorbidities may lead to drug–drug interactions which decrease drug efficacy or increase adverse reactions. Current practices rely on a one-size-fits-all dosing approach. Pharmacogenetic testing is generally reserved for addressing problems rather than used proactively to optimize care. We hypothesized that burn and surgery patients will have one or more genetic variants in drug metabolizing pathways used by one or more medications administered during the patient’s hospitalization. The aim of this study was to determine the frequency of variants with abnormal function in the primary drug pathways and identify which medications may be impacted. Genetic (19 whole exome and 11 whole genome) and medication data from 30 pediatric burn and surgery patients were analyzed to identify pharmacogene–drug associations. Nineteen patients were identified with predicted altered function in one or more of the following genes: CYP2C9, CYP2C19, CYP2D6, and CYP3A4. The majority had decreased function, except for several patients with CYP2C19 rapid or ultrarapid variants. Some drugs administered during hospitalization that rely on these pathways include hydrocodone, oxycodone, methadone, ibuprofen, ketorolac, celecoxib, diazepam, famotidine, diphenhydramine, and glycopyrrolate. Approximately one-third of the patients tested had functionally impactful genotypes in each of the primary drug metabolizing pathways. This study suggests that genetic variants may in part explain the vast variability in drug efficacy and suggests that future pharmacogenetics research may optimize dosing regimens.

An extended-release formulation of the NSAID meloxicam (MSR) is used to provide 72 h of continuous analgesia in many species, including rodents. Although standard formulations of meloxicam are frequently used in rats with no observable injection-site reactions, the potential adverse effects from MSR have not been characterized sufficiently nor has a prospective study of these effects been performed in rats. To address this deficiency, we evaluated injection-site reactions after a single subcutaneous administration of MSR (n = 16) or sterile saline (SC, n = 6) in the flank of age- and sex-matched Sprague–Dawley rats. Mass and erythema scores were measured daily for 2 wk, and injection sites were collected for histopathology after euthanasia. Rats were randomly selected for euthanasia at 7 d (n = 12) or 14 d (n = 10) after injection to capture the subacute and chronic phases of mass and erythematic lesion formation. No rats in the SC group developed lesions, whereas all 16 MSR-treated rats developed masses. The median time to first mass in the MSR treatment group was 3 d (95% CI, 2–3 d), and nearly 8 d for erythema (95% CI, 6.7–9.1 d). The trajectory of mass lesion severity showed rapid progression from score 1 at onset (day 2 or 3) to score 2 for almost all animals by day 5 or 6. Histopathology was characterized by localized inflammation with central necrosis and peripheral fibrosis, with some sections showing developing draining tracts. Given the high prevalence and severity of localized skin reactions, MSR analgesia should be considered carefully for Sprague–Dawley rats.

Author(s): Langer, Henning T; Mossakowski, Agata A; Willis, Brandon J; Grimsrud, Kristin N; Wood, Joshua A; Lloyd, Kevin CK; Zbinden-Foncea, Hermann; Baar, Keith | Abstract: BackgroundDesminopathy is a clinically heterogeneous muscle disease caused by over 60 different mutations in desmin. The most common mutation with a clinical phenotype in humans is an exchange of arginine to proline at position 350 of desmin leading to p.R350P. We created the first CRISPR-Cas9 engineered rat model for a muscle disease by mirroring the R350P mutation in humans.MethodsUsing CRISPR-Cas9 technology, Des c.1045-1046 (AGG g CCG) was introduced into exon 6 of the rat genome causing p.R349P. The genotype of each animal was confirmed via quantitative PCR. Six male rats with a mutation in desmin (n = 6) between the age of 120-150 days and an equal number of wild type littermates (n = 6) were used for experiments. Maximal plantar flexion force was measured in vivo and combined with the collection of muscle weights, immunoblotting, and histological analysis. In addition to the baseline phenotyping, we performed a synergist ablation study in the same animals.ResultsWe found a difference in the number of central nuclei between desmin mutants (1 ± 0.4%) and wild type littermates (0.2 ± 0.1%; P l 0.05). While muscle weights did not differ, we found the levels of many structural proteins to be altered in mutant animals. Dystrophin and syntrophin were increased 54% and 45% in desmin mutants, respectively (P l 0.05). Dysferlin and Annexin A2, proteins associated with membrane repair, were increased two-fold and 32%, respectively, in mutants (P l 0.05). Synergist ablation caused similar increases in muscle weight between mutant and wild type animals, but changes in fibre diameter revealed that fibre hypertrophy in desmin mutants was hampered compared with wild type animals (P l 0.05).ConclusionsWe created a novel animal model for desminopathy that will be a useful tool in furthering our understanding of the disease. While mutant animals at an age corresponding to a preclinical age in humans show no macroscopic differences, microscopic and molecular changes are already present. Future studies should aim to further decipher those biological changes that precede the clinical progression of disease and test therapeutic approaches to delay disease progression.

Introduction Management of critically ill patients requires simultaneous administration of many medications. These patients may have co-morbidities and drug-drug interactions which may result in decreased drug efficacy or increased risk of adverse reactions. Children are of particular concern as they may be even more sensitive to adverse drug reactions. Current practices rely on a one-size-fits-all approach for most medication dosing. Alternatively, precision medicine evaluates an individual’s genetic profile and adjusts individual therapeutic dosing. Pharmacogenetic testing is not generally implemented but is reserved for addressing an established problem rather than being used proactively to optimize clinical care. A greater understanding of the frequency of clinically significant genetic variants in drug pathways and identification of the drugs most commonly impacted by genetic makeup is needed to incorporate pharmacogenetics into medical care. We hypothesize several patients will have one or more genetic variants in drug metabolizing pathways used by one or more medications administered during hospitalization. The aims of this study are to determine the frequency of abnormal genetic variants in the primary drug pathways and assess what medications may be impacted. Methods Genetic data from 30 pediatric burn and surgery patients was collected to identify genetic variants in drug metabolizing pathways. We also evaluated drugs potentially impacted by these variants that were administered during the hospitalization. 19 whole exome and 11 whole genome sequencing datasets were analyzed using Aldy allelic decomposition software to identify haplotypes in cytochrome P450 (CYP) metabolizing enzyme genes. Results 17 patients were identified with predicted altered function in 1 or more of the following CYP genes: 2C9, 2C19, 2D6, 3A4 and 3A5. The majority had decreased function, except for several patients with CYP2C19 variants with rapid or ultrarapid phenotypes. Drugs administered during hospitalization that rely on these pathways for primary metabolism include hydrocodone, oxycodone, methadone, ibuprofen, ketorolac, celebrex, diazepam, famotidine, diphenhydramine and glycopyrrolate. Conclusions This research demonstrates that approximately 1/4 to 1/3 of patients have functionally impactful haplotypes in the primary drug metabolizing pathways. There is great need for future clinical research to further evaluate the clinical relevance of these haplotypes and the additional impact of drug-drug interactions and other clinical confounders that additionally impact drug efficacy.

The Mutant Mouse Resource and Research Center (MMRRC) Program is the pre-eminent public national mutant mouse repository and distribution archive in the USA, serving as a national resource of mutant mice available to the global scientific community for biomedical research. Established more than two decades ago with grants from the National Institutes of Health (NIH), the MMRRC Program supports a Consortium of regionally distributed and dedicated vivaria, laboratories, and offices (Centers) and an Informatics Coordination and Service Center (ICSC) at three academic teaching and research universities and one non-profit genetic research institution. The MMRRC Program accepts the submission of unique, scientifically rigorous, and experimentally valuable genetically altered and other mouse models donated by academic and commercial scientists and organizations for deposition, maintenance, preservation, and dissemination to scientists upon request. The four Centers maintain an archive of nearly 60,000 mutant alleles as live mice, frozen germplasm, and/or embryonic stem (ES) cells. Since its inception, the Centers have fulfilled 13,184 orders for mutant mouse models from 9591 scientists at 6626 institutions around the globe. Centers also provide numerous services that facilitate using mutant mouse models obtained from the MMRRC, including genetic assays, microbiome analysis, analytical phenotyping and pathology, cryorecovery, mouse husbandry, infectious disease surveillance and diagnosis, and disease modeling. The ICSC coordinates activities between the Centers, manages the website (mmrrc.org) and online catalog, and conducts communication, outreach, and education to the research community. Centers preserve, secure, and protect mutant mouse lines in perpetuity, promote rigor and reproducibility in scientific experiments using mice, provide experiential training and consultation in the responsible use of mice in research, and pursue cutting edge technologies to advance biomedical studies using mice to improve human health. Researchers benefit from an expansive list of well-defined mouse models of disease that meet the highest standards of rigor and reproducibility, while donating investigators benefit by having their mouse lines preserved, protected, and distributed in compliance with NIH policies.

Opioids are essential first line analgesics for pain management after burn injury. Opioid dosing remains challenging in burn patients, particularly in children, due to the immense variability in efficacy between patients. Opioid pharmacokinetics are altered in burned children, increasing variability and obviating dosing regimens extrapolated from adult-data. The present study aimed to characterize variability in fentanyl pharmacokinetics and identify significant contributors to variability in children with ≥10% total body surface area burn requiring fentanyl during routine wound care. We recorded patient demographics and clinical data. Blood samples were collected following fentanyl administration for pharmacokinetics at time 0, 30, 60, 120, and 240 minutes on day of admission and repeated on days 3 and 7. Serum fentanyl concentrations were quantified using tandem liquid chromatography mass spectrometry. Population analysis was used to estimate pharmacokinetics parameters. Fourteen patients, 1.2–17 years, with burns from 10–50.5% were included in analysis. A two-compartment model with body weight as a covariate best described fentanyl pharmacokinetics for the overall population. The population clearance and intercompartmental clearance were 7.19 and 2.16 L/hour, respectively, and the volume of distribution for the central and peripheral compartments was 4.01 and 25.1 L, respectively. Individual patient parameter estimates had extensive variability. This study confirmed the high variability in pediatric burn patient fentanyl pharmacokinetics and demonstrates similarities and differences to other populations reported in literature. Further research is needed with a larger number of patients to extensively investigate the impact of burns, genetic polymorphisms, and other factors on fentanyl efficacy and patient outcomes.

The sustained-release formulation of meloxicam (MSR) is a compounded NSAID that may provide pain relief for as long as 72 h after administration. MSR injection-site skin reactions have occurred in several species but have not previously been observed in mice. We investigated the development and progression of localized skin reactions after a single injection of MSR in Crl:CD1(ICR), C57BL/6J, and BALB/cJ mice. Each mouse received a subcutaneous injection of MSR (n = 60), standard-formulation meloxicam (MEL; n = 24) or saline (control; SC; n = 24) and was scored daily according to a 5-point system for erythema and mass characteristics. Mice were euthanized at either 7 or 14 d after injection and underwent postmortem analysis. MSR-treated mice had more erythematous and mass reactions than did MEL and SC mice. Mass lesions developed in 49 MSR mice (82%; 95% CI, 70% to 90%), 5 MEL animals (21%; 95% CI, 7% to 42%), and 1 SC mouse. MSR-treated BALB/cJ developed erythematous lesions less frequently than similarly treated Crl:CD1(ICR) or C57BL/6J. Lesions often were ventrolateral to the injection site. The median times to the appearance of mass and erythematous lesions were 2 d and 3 d, respectively. Histologically, the erythematous and mass reactions correlated with necrotizing to pyogranulomatous injection-site panniculitis. Inflammation severity scores at 7 and 14 d after injection were greater in the MSR-treated group than the other 2 groups. No strain- or sex-associated differences emerged except that inflammation severity scores at day 14 were higher in Crl:CD1(ICR) females than males. The character of the inflammatory response in MSR-treated mice did not differ between 7 and 14 d after injection, indicating that MSR-induced inflammation is slow to resolve. The ventral migration and delayed onset of MSR injection-site reactions could result in their being attributed to another cause or not being identified. Researchers and clinicians should be aware of the potential for slowly resolving injection-site reactions with MSR.

The Roux-en-Y Gastric Bypass (RYGB) mouse model is a vital tool for studying the pathophysiology of bariatric surgery and contributes greatly to research on obesity and diabetes. However, complications including postsurgical hypoglycemia can have profoundly negative effects. Unlike in humans, blood glucose (BG) is not typically managed in postoperative rodents, despite their critical role as translational models; without this management, rodents can experience hypoglycemia, potentially impairing wound healing, decreasing survivability, complicating interpretation of research data, and limiting translational utility. In this project, we sought to identify an optimal method for minimally invasive administration of dextrose in C57BL/6N (n = 16; 8 male, 8 female) mice. To do so, we characterized BG pharmacokinetic profiles after subcutaneous and oral–transmucosal (OTM) administration of dextrose. Compared with OTM dosage, the subcutaneous route provided more consistent and reliable delivery of glucose and did not cause significant adverse reactions. We then evaluated the frequency of hypoglycemic events after RYGB in C57BL/6N mice (n = 16; 8 male, 8 female) and the effects of subcutaneous dextrose supplementation on morbidity and mortality. BG measurement and behavioral pain assessment (grimace test) were performed for 3 d after surgery. Hypoglycemic (BG ≤ 60 mg/dL) animals were assigned to dose (5% dextrose SC) or no-dose treatment groups. Nearly all (87%) mice became hypoglycemic; 2 of these mice died. No significant intergroup difference in grimace score or mortality was detected. Overall, our results demonstrate that hypoglycemia is a frequent adverse event after RYGB in mice and that subcutaneous injection of dextrose is a safe and effective way to manage hypoglycemia. Further studies are necessary to optimize the intervention threshold and optimal dosage; regardless, we recommend glycemic management after RYGB surgery in mice.

BACKGROUND: Ceroid lipofuscinosis type 8 belongs to a heterogenous group of vision and life-threatening neurodegenerative diseases, neuronal ceroid lipofuscinosis (NCL). Effective therapy is limited to a single drug for treatment of ceroid lipofuscinosis type 2, necessitating animal disease models to facilitate further therapeutic development. Murine models are advantageous for therapeutic development due to easy genetic manipulation and rapid breeding, however appropriate genetic models need to be identified and characterized before being used for therapy testing. To date, murine models of ocular disease associated with ceroid lipofuscinosis type 8 have only been characterized in motor neuron degeneration mice. METHODS: Cln8(−/−) mice were produced by CRISPR/Cas9 genome editing through the International Mouse Phenotyping Consortium. Ophthalmic examination, optical coherence tomography, electroretinography, and ocular histology was performed on Cln8(−/−) mice and controls at 16 weeks of age. Quantification of all retinal layers, retinal pigmented epithelium, and the choriocapillaris was performed using images acquired with ocular coherence tomography and planimetry of histologic sections. Necropsy was performed to investigate concurrent systemic abnormalities. Clinical correlation with human patients with CLN8-associated retinopathy is provided. RESULTS: Retinal degeneration characterized by retinal pigment epithelium mottling, scattered drusen, and retinal vascular attenuation was noted in all Cln8(−/−) mice. Loss of inner and outer photoreceptor segment demarcation was noted on optical coherence tomography, with significant thinning of the whole retina (P=1e-9), outer nuclear layer (P=1e-9), and combined photoreceptor segments (P=1e-9). A global reduction in scotopic and photopic electroretinographic waveforms was noted in all Cln8(−/−) mice. Slight thickening of the inner plexiform layer (P=0.02) and inner nuclear layer (P=0.004), with significant thinning of the whole retina (P=0.03), outer nuclear layer (P=0.01), and outer photoreceptor segments (P=0.001) was appreciated on histologic sections. Scattered lipid vacuoles were noted in splenic red pulp of all Cln8(−/−) mice, though no gross systemic abnormalities were detected on necropsy. Retinal findings are consistent with those seen in patients with ceroid lipofuscinosis type 8. CONCLUSIONS: This study provides detailed clinical characterization of retinopathy in adult Cln8(−/−) mice. Findings suggest that Cln8(−/−) mice may provide a useful murine model for development of novel therapeutics needed for treating ocular disease in patients with ceroid lipofuscinosis type 8.

Pain management is critical for burn care. Unfortunately, interindividual variation in pharmacokinetics (PK) due to burn hypermetabolism and genetic polymorphisms can lead to treatment failures in this at-risk population. Analgesics may be affected by genetic polymorphisms affecting cytochrome P450 (CYP) drug metabolizing enzymes. Fentanyl is a common opiate primarily metabolized by CYP3A4 subtypes. Recent studies demonstrate CYP2D6 variants, affecting fentanyl PK. Functional CYP polymorphisms can significantly alter opiate levels resulting in inadequate analgesia or life-threatening toxicity. The goal of our study was to evaluate fentanyl PK and assess associations with CYP polymorphisms. We obtained samples from the previously banked blood of 13 patients (eight males and five females) with >20% TBSA burns. Mean (SD) patient age was 41.7 (14.5) years, and mean burn size was 25.8 (15.3) %TBSA. Plasma fentanyl was quantified, and CYP genotyping was performed. Pharmacokinetic analysis was performed using Monolix software (Lixsoft, France) with a two-compartment population model best-representing fentanyl profiles. Three CYP slow-metabolizing genotypes were identified, which included CYP2D6*9, CYP2D6*29, and CYP3A4*1B. All three patients with variant polymorphisms had increased serum fentanyl concentrations due to impaired clearance. This pilot study supports the need for further research in this topic, and CYP genotyping of individual patients prior to receiving opiate analgesics to inform precision-guided decisions, improve therapeutic efficacy, and, most importantly, increase patient well-being and safety.

Introduction Opioids are the predominant analgesic for pediatric burn patients. Burned children are frequently critically ill and require prolonged hospitalization with multiple surgical interventions. Pain associated with burns is severe, and failure to appropriately manage burn pain acutely can lead to long term negative consequences for these children. Prolonged opioid use, however, can lead to tolerance. While tolerance is anecdotally observed to develop at different rates in individual patients, the impact of genetic variability on the rate of development of tolerance is not known. This prospective study assesses the impact of genetic variability on opiate requirement in burned children. Methods A pilot study of pediatric burn patients was performed. Whole exome sequencing was used to evaluate genes involved in the metabolism and response to opioids. Oral morphine equivalents by weight (OME/kg) were calculated by day. Tolerance was determined by evaluating the rate of decline of OME/kg following the final major surgical procedure. Patients in the lowest third for rate of decline of opioid use were compared to other patients. Results Nine pediatric burn patients with median total body surface area of burn of 22% (IQR 12–36) and median age 7 years (IQR 5–13) were analyzed. Significant variability in the rate of decline of OME was observed, ranging from a decline 0.0971 OMEs/kg/day to an incline of 0.0057 OME/kg/day. Patients with a rate of decline in the lower third had a high frequency of missense mutations with predicted functional impact in the mu opioid receptor: 67% had a variant predicted to have functional impact, compared to 50% of patients in the upper two thirds. Two patients overall had missense mutations with predicted functional impact in the delta opioid receptor, with one having more rapidly developed tolerance. Conclusions The rate at which pediatric burn patients develop tolerance is variable. Variants in the mu opioid receptor may contribute to the rate at which patients develop tolerance. The function of many variants identified in this study is unknown, and their contribution to the development of tolerance requires further studies. Large scale studies to evaluate the rate of variants in the population and their relationship to tolerance development are critical to formulate personalized pain management for burned children.

Introduction ”One-size fits all” opioid dosing often results in a lack of efficacy or toxic consequences. Patients are heterogeneous; their drug sensitivity varies, potentially impacting therapeutic outcomes. Implementation of pharmacogenetic testing in the clinical setting is needed to improve precision dosing, especially in the critically ill (e.g. burns). However, due to the lack of comprehensive data addressing the functional impact of genetic variants, universal implementation of genetic screening is not yet possible. While animal models provide valuable data, they do not capture the vast heterogeneity and comorbidities of patients. Clinical pharmacogenetic studies are needed to advance our understanding of genetic variability and clinical impacts on opioid efficacy. The purpose of this report is to describe the challenges of clinical opioid pharmacogenetic studies in burn patients. Methods We performed two studies: 1) a pilot study evaluating CYP gene haplotypes in 13 adult burn patients receiving fentanyl using remnant samples and 2) a pediatric burn patient fentanyl pharmacogenetic study. In the pediatric study, we initially screened with a customized 18 gene panel (opioid pathway specific), and later expanded to whole exome analysis. Results We identified 3 adult slow-metabolizers, one with a CYP3A4 and two with CYP2D6 haplotypes and an average of 80+ variants identified in the 18 genes in preliminary analysis of pediatric patients. Multiple challenges were identified in conducting clinical observational studies. Although remnant samples can be hypothesis-generating, clinical data linkage is limited, decreasing the ability for covariate analysis to investigate clinical factors contributing to altered fentanyl metabolism. The use of a commercial haplotype panel, while convenient, only identifies known haplotypes and doesn’t identify all variants in patients. Research protocols must be tailored to clinical workflow. Repeated dosing of fentanyl, which is standard of care but may not be detailed in medical record charting, predisposes research analysis to inaccuracies. Sparse blood sampling, errors in blood draw methodology and loss of vascular access, particularly in pediatrics, can render data sets unanalyzable. Conclusions While we have faced many challenges, overall, these studies have produced valuable data to enable better future clinical research design. Educating bedside nurses on study goals, teaching investigators about clinical workflow, and trouble-shooting proper sample collection and charting are essential elements of a successful study. Finally, minimizing sample volume and optimizing sample time points allows for better study adherence and more accurate analysis. Applicability of Research to Practice Lessons learned from these studies will aid in the optimization of study design of future burns pharmacogenetic clinical studies.

Studies indicate that the gut microbiota (GM) can significantly influence both local and systemic host physiologic processes. With rising concern for optimization of experimental reproducibility and translatability, it is essential to consider the GM in study design. However, GM profiles can vary between rodent producers making consistency between models challenging. To circumvent this, we developed outbred CD1 mouse colonies with stable, complex GM profiles that can be used as donors for a variety of GM transfer techniques including rederivation, co-housing, cross-foster, and fecal microbiota transfer (FMT). CD1 embryos were surgically transferred into CD1 or C57BL/6 surrogate dams that varied by GM composition and complexity to establish four separate mouse colonies harboring GM profiles representative of contemporary mouse producers. Using targeted 16S rRNA amplicon sequencing, subsequent female offspring were found to have similar GM profiles to surrogate dams. Furthermore, breeding colonies of CD1 mice with distinct GM profiles were maintained for nine generations, demonstrating GM stability within these colonies. To confirm GM stability, we shipped cohorts of these four colonies to collaborating institutions and found no significant variation in GM composition. These mice are an invaluable experimental resource that can be used to investigate GM effects on mouse model phenotype.

© 2018 National Academy of Sciences. All Rights Reserved. Heart failure (HF) following myocardial infarction (MI) is associated with high incidence of cardiac arrhythmias. Development of therapeutic strategy requires detailed understanding of electrophysiological remodeling. However, changes of ionic currents in ischemic HF remain incompletely understood, especially in translational largeanimal models. Here, we systematically measure the major ionic currents in ventricular myocytes from the infarct border and remote zones in a porcine model of post-MI HF. We recorded eight ionic currents during the cell's action potential (AP) under physiologically relevant conditions usingselfAP-clamp sequential dissection. Compared with healthy controls, HF-remote zone myocytes exhibited increased late Na+ current, Ca2+-activated K+ current, Ca2+-activated Cl- current, decreased rapid delayed rectifier K+current, and altered Na+/Ca2+exchange current profile. In HF-border zone myocytes, the above changes also occurred but with additional decrease of L-type Ca2+current, decrease of inward rectifier K+current, and Ca2+release-dependent delayed after-depolarizations. Our data reveal that the changes in any individual current are relatively small, but the integrated impacts shift the balance between the inward and outward currents to shorten AP in the border zone but prolong AP in the remote zone. This differential remodeling in post-MI HF increases the inhomogeneity of AP repolarization, which may enhance the arrhythmogenic substrate. Our comprehensive findings provide a mechanistic framework for understanding why single-channel blockers may fail to suppress arrhythmias, and highlight the need to consider the rich tableau and integration of many ionic currents in designing therapeutic strategies for treating arrhythmias in HF.

Special populations, including women (non-pregnant and pregnant), pediatrics, and the elderly, require additional consideration with regard to clinical research. There are very specific regulatory laws, which protect these special populations, that need to be understood and adhered to in order to perform clinical research. This review provides a broad overview of some of the physiological differences in special populations and discusses how these differences may affect study design and regulatory considerations. These various special populations, with respect to regulatory affairs, are clearly defined within the Code of Federal Regulations. The definition of "special population" exists to provide enhanced awareness of their vulnerabilities, thereby allowing the creation of regulatory guidance aimed to decrease injury or outright harm. Currently, progress is being made to be more inclusive of special populations in clinical trials. This reflects changing attitudes towards drug information, with it being more representative of those patients that will ultimately be prescribed or exposed to the therapy. However, all research undertaken in these populations should be performed in a manner that ensures all protections of each participant are upheld.

Severe burn injury results in a multifaceted physiological response that significantly alters drug pharmacokinetics and pharmacodynamics (PK/PD). This response includes hypovolemia, increased vascular permeability, increased interstitial hydrostatic pressure, vasodilation, and hypermetabolism. These physiologic alterations impact drug distribution and excretion-thus varying the drug therapeutic effect on the body or microorganism. To this end, in order to optimize critical care for the burn population it is essential to understand how burn injury alters PK/PD parameters. The purpose of this article is to describe the relationship between burn injury and drug PK/PD. We conducted a literature review via PubMed and Google to identify burn-related PK/PD studies. Search parameters included "pharmacokinetics," "pharmacodynamics," and "burns." Based on our search parameters, we located 38 articles that studied PK/PD parameters specifically in burns. Twenty-seven articles investigated PK/PD of antibiotics, 10 assessed analgesics and sedatives, and one article researched an antacid. Out of the 37 articles, there were 19 different software programs used and eight different control groups. The mechanisms behind alterations in PK/PD in burns remain poorly understood. Dosing techniques must be adapted based on burn injury-related changes in PK/PD parameters in order to ensure drug efficacy. Although several PK/PD studies have been undertaken in the burn population, there is wide variation in the analytical techniques, software, and study sample sizes used. In order to refine dosing techniques in burns and consequently improve patient outcomes, there must be harmonization among PK/PD analyses.

Background To define the pharmacokinetic profile of propofol 5% microemulsion formulation in horses. Methods First, propofol was administered as bolus injection (2 mg kg−1) to six xylazine-sedated horses. Secondly, after sedation and bolus injection, propofol was maintained with continuous infusion for 3 h [8.1 (sd 3.2) mg kg−1 h−1] to the same six horses. Thirdly, in two horses, a commercial propofol was used for comparison. Response to noxious stimulation was used to evaluate analgesia. Venous blood samples were obtained to measure propofol plasma concentration using liquid chromatography-mass spectrometry analysis. The plasma concentrations were related to the anaesthesia characteristics to determine the ED50. Results The pharmacokinetic profile of propofol is best characterized by a non-compartmental model. The mean (confidence interval) for area under plasma concentration–time curve, elimination half-life, mean residence time, and clearance was 41 min µg ml−1 (±7.7), 44.8 min (±21.3), 13.7 min (±3.2), and 45.8 ml min−1 kg−1 (±6.5), respectively. Linear regression analysis showed a correlation between plasma concentration and infusion rate (r2=0.47). Most propofol infusion rates did not inhibit the response to noxious stimulation and rates above 11.9 mg kg−1 h−1 caused involuntary muscle contractions. Better recoveries were associated with lower propofol plasma concentrations. Propofol plasma concentration frequently increased when horses woke from anaesthesia. Conclusions Caution is warranted when propofol is used for continuous infusion due to variable kinetics, myoclonal activity, poor analgesia, and less desirable recovery quality.

Objective To determine if binge ethanol consumption before ovulation affects oocyte quality, gene expression, and subsequent embryo development. Design Binge levels of ethanol were given twice weekly for 6 months, followed by a standard in vitro fertilization cycle and subsequent natural mating. Setting National primate research center. Animal(s) Adult female rhesus monkeys. Intervention(s) Binge levels of ethanol, given twice weekly for 6 months before a standard in vitro fertilization cycle with or without embryo culture. With in vivo development, ethanol treatment continued until pregnancy was identified. Main Outcome Measure(s) Oocyte and cumulus/granulosa cell gene expression, embryo development to blastocyst, and pregnancy rate. Result(s) Embryo development in vitro was reduced; changes were found in oocyte and cumulus cell gene expression; and spontaneous abortion during very early gestation increased. Conclusion(s) This study provides evidence that binge drinking can affect the developmental potential of oocytes even after alcohol consumption has ceased.

Inorganic polyphosphate (polyP) is a naturally occurring polyanion made of ten to several hundred orthophosphates linked together by phosphoanhydride bonds. Specific physiological roles of polyP vary dramatically depending on its size, concentration, tissue and subcellular localization. Recently we reported that mitochondria of rabbit ventricular myocytes contain significant amounts (280 ± 60 pmol/mg of protein) of polyP with an average length of 25 orthophosphates, and that polyP is involved in Ca2+-dependent activation of the mitochondrial permeability transition pore (mPTP). Using DAPI as a probe for polyP, we showed that polyP levels depend on the activity of the mitochondrial respiratory chain. Here, we visualized intracellular polyP distribution in cardiomyocytes using the affinity of the Xpress epitope-tagged recombinant polyphosphate-binding domain (PPBD) of E. coli exopolyphosphatase and immunocytochemical approach. Primarily mitochondrial location of polyP was demonstrated in both control and heart failure (HF) myocytes from two different HF models: (1), non-ischemic rabbit HF model induced by combined aortic insufficiency and stenosis and (2), targeted microbead embolization of the first diagonal branch of left anterior descending coronary artery in Yucatan mini-pigs. However, enhanced formation of polyP dense spots was observed in HF conditions. Furthermore, polyP dense spots overlapped with poly-beta-hydroxybutyrate (PHB) accumulation areas in HF myocytes as detected with specific PHB antibodies (anti-PHB IgG) raised against a synthetic 8-mer of PHB. It is known that polyP can form channels with Ca2+ and PHB, a polymerized form of the ketone body beta-hydroxybutyrate, with characteristics similar to mPTP. These data suggest that polyP-PHB complex formation in HF myocytes could contribute to the enhanced propensity of mPTP opening despite decreased mitochondrial Ca2+ uptake.

The present study characterizes the pharmacokinetic (PK) and pharmacodynamic (PD) relationships of the α2-adrenergic receptor agonists detomidine (DET), medetomidine (MED) and dexmedetomidine (DEX) in parallel groups of horses from in vivo data after single bolus doses. Head height (HH), heart rate (HR), and blood glucose concentrations were measured over 6 h. Compartmental PK and minimal physiologically based PK (mPBPK) models were applied and incorporated into basic and extended indirect response models (IRM). Population PK/PD analysis was conducted using the Monolix software implementing the stochastic approximation expectation maximization algorithm. Marked reductions in HH and HR were found. The drug concentrations required to obtain inhibition at half-maximal effect (IC50 ) were approximately four times larger for DET than MED and DEX for both HH and HR. These effects were not gender dependent. Medetomidine had a greater influence on the increase in glucose concentration than DEX. The developed models demonstrate the use of mechanistic and mPBPK/PD models for the analysis of clinically obtainable in vivo data.

BackgroundIntravenous racemic ketamine is commonly administered for procedural sedation, although few pharmacokinetic studies have been conducted among children. Moreover, an optimal sampling schedule has not been derived to enable the conduct of pharmacokinetic studies that minimally inconvenience study participants.MethodsConcentration-time data were obtained from 57 children who received 1-1.5 mg.kg(-1) of racemic ketamine as an intravenous bolus. A population pharmacokinetic analysis was conducted using nonlinear mixed effects models, and the results were used as inputs to develop a D-optimal sampling schedule.ResultsThe pharmacokinetics of ketamine were described using a two-compartment model. The volume of distribution in the central and peripheral compartments were 20.5 l.70 kg(-1) and 220 l.70 kg(-1), respectively. The intercompartmental clearance and total body clearance were 87.3 and 87.9 l.h(-1).70 kg(-1), respectively. Population parameter variability ranged from 34% to 98%. Initially, blood samples were drawn on 3-6 occasions spanning a range of 14-152 min after dosing. Using these data, we determined that four optimal sampling windows occur at 1-5, 5.5-7.5, 10-20, and 90-180 min after dosing. Monte Carlo simulations indicated that these sampling windows produced precise and unbiased ketamine pharmacokinetic parameter estimates.ConclusionAn optimal sampling schedule was developed that allowed assessment of the pharmacokinetic parameters of ketamine among children requiring short-term procedural sedation.

The aim of the study was to describe the pharmacokinetics and selected pharmacodynamics of intravenous dexmedetomidine in horses. Eight adult horses received 5 μg/kg dexmedetomidine IV. Blood samples were collected before and for 10 h after drug administration to determine dexmedetomidine plasma concentrations. Pharmacokinetic parameters were calculated using noncompartmental analysis. Data from one outlier were excluded from the statistical summary. Behavioral and physiological responses were recorded before and for 6 h after dexmedetomidine administration. Dexmedetomidine concentrations decreased rapidly (elimination half-life of 8.03 ± 0.84 min). Time of last detection varied from 30 to 60 min. Bradycardia was noted at 4 and 10 min after drug administration (26 ± 8 and 29 ± 8 beats/min respectively). Head height decreased by 70% at 4 and 10 min and gradually returned to baseline. Ability to ambulate was decreased for 60 min following drug administration, and mechanical nociceptive threshold was increased during 30 min. Blood glucose peaked at 30 min (134 ± 24 mg/dL) and borborygmi were decreased for the first hour after dexmedetomidine administration. Dexmedetomidine was quickly eliminated as indicated by the rapid decrease in plasma concentrations. Physiological, behavioral, and analgesic effects observed after dexmedetomidine administration were of short duration.

Objective To describe the pharmacodynamics and pharmacokinetics following an intravenous (IV) bolus dose of medetomidine in the horse. Study design Prospective experimental trial. Animals Eight, mature healthy horses age 11.7 ± 4.6 (mean ± SD) years, weighing 557 ± 54 kg. Methods Medetomidine (10 μg kg −1 ) was administered IV. Blood was sampled at fixed time points from before drug administration to 48 hours post administration. Behavioral, physiological and biochemical data were obtained at predetermined time points from 0 minutes to 24 hours post administration. An algometer was also used to measure threshold responses to noxious stimuli. Medetomidine concentrations were determined by liquid chromatography-Mass Spectrometry and used for calculation of pharmacokinetic parameters using noncompartmental and compartmental analysis. Results Pharmacokinetic analysis estimated that medetomidine peaked (8.86 ± 3.87 ng mL −1 ) at 6.4 ± 2.7 minutes following administration and was last detected at 165 ± 77 minutes post administration. Medetomidine had a clearance of 39.6 ± 14.6 mL kg −1 minute −1 and a volume of distribution of 1854 ± 565 mL kg −1 . The elimination half-life was 29.1 ± 12.5 minutes. Glucose concentration reached a maximum of 176 ± 46 mg dL −1 approximately 1 hour post administration. Decreased heart rate, respiratory rate, borborygmi, packed cell volume, and total protein concentration were observed following administration. Horses lowered their heads from 107 ± 12 to 20 ± 10 cm within 10 minutes of drug administration and gradually returned to normal. Horse mobility decreased after drug administration. An increased mechanical threshold was present from 10 to 45 minutes and horses were less responsive to sound. Conclusion and clinical relevance Behavioral and physiological effects following intravenous administration positively correlate with pharmacokinetic profiles from plasma medetomidine concentrations. Glucose concentration gradually transiently increased following medetomidine administration. The analgesic effect of the drug appeared to have a very short duration.

Summary Reasons for performing study: Detomidine is commonly used i.v. for sedation and analgesia in horses, but the pharmacokinetics and metabolism of this drug have not been well described. Objectives: To describe the pharmacokinetics of detomidine and its metabolites, 3-hydroxy-detomidine (OH-detomidine) and detomidine 3-carboxylic acid (COOH-detomidine), after i.v. and i.m. administration of a single dose to horses. Methods: Eight horses were used in a balanced crossover design study. In Phase 1, 4 horses received a single dose of i.v. detomidine, administered 30 μg/kg bwt and 4 a single dose i.m. 30 ug/kg bwt. In Phase 2, treatments were reversed. Plasma detomidine, OH-detomidine and COOH-detomidine were measured at predetermined time points using liquid chromatography-mass spectrometry. Results: Following i.v. administration, detomidine was distributed rapidly and eliminated with a half-life (t1/2(el)) of approximately 30 min. Following i.m. administration, detomidine was distributed and eliminated with t1/2(el) of approximately one hour. Following, i.v. administration, detomidine clearance had a mean, median and range of 12.41, 11.66 and 10.10–18.37 ml/min/kg bwt, respectively. Detomidine had a volume of distribution with the mean, median and range for i.v. administration of 470, 478 and 215–687 ml/kg bwt, respectively. OH-detomidine was detected sooner than COOH-detomidine; however, COOH-detomidine had a much greater area under the curve. Conclusions and potential relevance: These pharmacokinetic parameters provide information necessary for determination of peak plasma concentrations and clearance of detomidine in mature horses. The results suggest that, when a longer duration of plasma concentration is warranted, the i.m. route should be considered.