Evan D Kharasch

Washington University in St. Louis, San Luis, Missouri, United States

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Publications (258)1312.54 Total impact

  • Evan D Kharasch, Markus W Hollmann
    Anesthesia and analgesia 05/2015; 120(5):983-4. DOI:10.1213/ANE.0000000000000667 · 3.42 Impact Factor
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    ABSTRACT: The bio-enabled synthesis of a novel class of surface enhanced Raman scattering probes is presented for functional imaging with built-in and accessible electromagnetic hotspots formed between densely packed satellites grown on a plasmonic core. The superstructures serve as nanoscale sensors to spatiotemporally map intravesicular pH changes along endocytic pathways inside live cells. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Advanced Healthcare Materials 05/2015; DOI:10.1002/adhm.201500227 · 4.88 Impact Factor
  • Evan D Kharasch, Christina Friedel, Sarah Gadel
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    ABSTRACT: Methadone is a long-acting opioid with considerable unexplained interindividual variability in clearance. Cytochrome P4502B6 (CYP2B6) mediates clinical methadone clearance and metabolic inactivation via N-demethylation to 2-ethyl-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP). Retrospective studies suggest that individuals with the CYP2B6*6 allelic variant have higher methadone plasma concentrations. Catalytic activities of CYP2B6 variants are highly substrate- and expression-system dependent. This investigation evaluated methadone N-demethylation by expressed human CYP2B6 allelic variants in an insect cell co-expression system containing P450 reductase. Additionally, the influence of co-expressing cytochrome b5, whose role in metabolism can be inhibitory or stimulatory, and dependent on the CYP isoform and substrate, on methadone metabolism was evaluated. EDDP formation from therapeutic (0.25-1 μM) R- and S-methadone concentrations was CYP2B6.4 ≥ CYP2B6.1 ≥ CYP2B6.5 > CYP2B6.9 ≈ CYP2B6.6, and undetectable from CYP2B6.18. Co-expression of b5 had small and variant-specific effects at therapeutic methadone concentrations, but at higher concentrations stimulated EDDP formation by CYP2B6.1, CYP2B6.4, CYP2B6.5, and CYP2B6.9 but not CYP2B6.6. In vitro intrinsic clearances were generally CYP2B6.4 ≥ CYP2B6.1 > CYP2B6.5 > CYP2B6.9 ≥ CYP2B6.6. Stereoselective methadone metabolism (S>R) was maintained with all CYP2B6 variants. These results show that methadone N-demethylation by CYP2B6.4 is greater compared with CYP2B6.1, while CYP2B6.9 and CYP2B6.6 (which both contain the 516G>T, Q172H polymorphism), are catalytically deficient. The presence or absence of b5 in expression systems may explain previously reported disparate catalytic activities of CYP2B6 variants for specific substrates. Differences in methadone metabolism by CYP2B6 allelic variants provide a mechanistic understanding for pharmacogenetic variability in clinical methadone metabolism and clearance. The American Society for Pharmacology and Experimental Therapeutics.
    Drug metabolism and disposition: the biological fate of chemicals 04/2015; 43(7). DOI:10.1124/dmd.115.064352 · 3.33 Impact Factor
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    ABSTRACT: Drug interactions involving methadone and/or HIV antiretrovirals can be problematic. Mechanisms whereby antiretrovirals induce clinical methadone clearance are poorly understood. Methadone is N-demethylated to 2-ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) by CYP2B6 and CYP3A4 in vitro, but by CYP2B6 in vivo. This investigation evaluated human hepatocytes as a model for methadone induction, and tested the hypothesis that methadone and EDDP are substrates for human drug transporters. Human hepatocyte induction by several antiretrovirals of methadone N-demethylation, and CYP2B6 and CYP3A4 transcription, protein expression and catalytic activity, and pregnane X receptor (PXR) activation were evaluated. Methadone and EDDP uptake and efflux by overexpressed transporters were also determined. Methadone N-demethylation was generally not significantly increased by the antiretrovirals. CYP2B6 mRNA and activity (bupropion N-demethylation) were induced by several antiretrovirals, as were CYP3A4 mRNA and protein expression, but only indinavir increased CYP3A activity (alfentanil dealkylation). CYP upregulation appeared related to PXR activation. Methadone was not a substrate for uptake (OCT1, OCT2, OCT3, OATP1A2, OATP1B1, OATP1B3, OATP2B1) or efflux (P-gp, BCRP) transporters. EDDP was a good substrate for P-gp, BCRP, OCT1, OCT3, OATP1A2, and OATP1B1. OATP1A2- and OCT3-mediated EDDP uptake, and BCRP-mediated EDDP efflux transport, were inhibited by several antiretrovirals. Results show that hepatocyte methadone N-demethylation resembles expressed and liver microsomal metabolism more than clinical metabolism. Compared with clinical studies, hepatocytes underreport induction of methadone metabolism by HIV drugs. Hepatocytes are not a good predictive model for clinical antiretroviral induction of methadone metabolism and not a substitute for clinical studies. EDDP is a transporter substrate, and is susceptible to transporter-mediated interactions.
    Biochemical pharmacology 03/2015; 95(2). DOI:10.1016/j.bcp.2015.03.007 · 4.65 Impact Factor
  • Evan D Kharasch
    Anesthesiology 03/2015; 122(5). DOI:10.1097/ALN.0000000000000634 · 6.17 Impact Factor
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    ABSTRACT: Prolonged administration of nitrous oxide causes an increase in plasma homocysteine in children via vitamin B12 inactivation. However, it is unclear whether nitrous oxide doses used in clinical practice cause adverse hematological effects in pediatric patients. This retrospective study included 54 pediatric patients undergoing elective spinal surgery: 41 received nitrous oxide throughout anesthesia (maintenance group), 9 received nitrous oxide for induction and/or emergence (induction/emergence group), and 4 did not receive nitrous oxide (nitrous oxide-free group). Complete blood counts obtained before and up to 4 days after surgery were assessed for anemia, macrocytosis/microcytosis, anisocytosis, hyperchromatosis/hypochromatosis, thrombocytopenia, and leukopenia. The change (Δ) from preoperative to the highest postoperative value was calculated for mean corpuscular volume (MCV) and red cell distribution width (RDW). No pancytopenia was present in any patient after surgery. All patients had postoperative anemia, and none had macrocytosis. Postoperative MCV (mean [99% confidence interval]) peaked at 86 fL (85-88 fL), 85 fL (81-89 fL), and 88 fL (80-96 fL) and postoperative RDW at 13.2% (12.8-13.5%), 13.3% (12.7-13.8%), and 13.0% (11.4-14.6%) for the maintenance group, the induction/emergence group, and the nitrous oxide-free group. Two patients in the maintenance group (5%) developed anisocytosis (RDW >14.6%), but none in the induction/emergence group or in the nitrous oxide-free group (P = 0.43). Both ΔMCV (P = 0.52) and ΔRDW (P = 0.16) were similar across all groups. Nitrous oxide exposure for up to 8 hours is not associated with megaloblastic anemia in pediatric patients undergoing major spinal surgery.
    Anesthesia & Analgesia 02/2015; DOI:10.1213/ANE.0000000000000642 · 3.42 Impact Factor
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    ABSTRACT: To evaluate the sensitivity and specificity of urine aquaporin 1 (AQP1) and perilipin 2 (PLIN2) concentrations to diagnose clear cell or papillary renal cell carcinoma (RCC) by comparing urine concentrations of these unique biomarkers in patients with RCC, noncancer renal masses, bladder cancer, and prostate cancer. From February 1, 2012, through October 31, 2012, preoperative urine samples were obtained from patients with a presumptive diagnosis of RCC based on an imaged renal mass, prostate cancer, or transitional cell bladder cancer. Imaged renal masses were diagnosed postnephrectomy-as malignant or benign-by histology. Urine AQP1 and PLIN2 concentrations were measured by using a sensitive and specific Western blot and normalized to urine creatinine concentration. Median concentrations of urine AQP1 and PLIN2 in patients with clear cell and papillary RCC (n=47) were 29 and 36 relative absorbance units/mg urine creatinine, respectively. In contrast, median concentrations in patients with bladder cancer (n=22) and prostate cancer (n=27), patients with chromophobe tumors (n=7), and patients with benign renal oncocytomas (n=9) and angiomyolipomas (n=7) were all less than 10 relative absorbance units/mg urine creatinine (Kruskal-Wallis test, P<.001 vs RCC for both biomarkers) and comparable with those in healthy controls. The area under the receiver operating characteristic curve ranged from 0.99 to 1.00 for both biomarkers. These results support the specificity and sensitivity of urine AQP1 and PLIN2 concentrations for RCC. These novel tumor-specific proteins have high clinical validity and high potential as specific screening biomarkers for clear cell and papillary RCC as well as in the differential diagnosis of imaged renal masses. clinicaltrials.gov Identifier: NCT00851994. Copyright © 2015 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.
    Mayo Clinic Proceedings 01/2015; 90(1):35-42. DOI:10.1016/j.mayocp.2014.10.005 · 5.81 Impact Factor
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    ABSTRACT: Long-acting opioid agonists methadone and l-α-acetylmethadol (LAAM) prevent withdrawal in opioid-dependent persons. Attempts to synthesize [11C]-methadone for PET evaluation of brain disposition were unsuccessful. Owing, however, to structural and pharmacologic similarities, we aimed to develop [11C]LAAM as a PET ligand to probe the brain exposure of long-lasting opioids in humans. This manuscript describes [11C]LAAM synthesis and its biodistribution in mice. The radiochemical synthetic strategy afforded high radiochemical yield, purity and specific activity, thereby making the synthesis adaptable to automated modules.
    Applied Radiation and Isotopes 09/2014; 91:135–140. DOI:10.1016/j.apradiso.2014.05.019 · 1.06 Impact Factor
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    ABSTRACT: Interindividual variability and drug interaction studies suggest that blood-brain barrier drug transporters mediate human methadone brain biodistribution. In vitro and animal studies suggest that methadone is a substrate for the efflux transporter P-glycoprotein, and that P-glycoprotein-mediated transport influences brain access and pharmacologic effect. This investigation tested whether methadone is a transporter substrate in humans.
    Anesthesiology 07/2014; 121(6). DOI:10.1097/ALN.0000000000000391 · 6.17 Impact Factor
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    ABSTRACT: Ritonavir, an HIV protease inhibitor, is successfully used for the prevention and treatment of HIV infections. Ritonavir pharmacokinetics are complicated by inhibition, induction and pharmacogenetics of cytochrome P450 (CYP) enzymes mediating its clearance. This investigation revealed that CYP2J2, along with CYP3A4/5 and CYP2D6, efficiently metabolizes ritonavir, and to a CYP2J2-specific (minor) metabolite. Chemical inhibition of ritonavir metabolism, clearance, KI/kinact and abundance of CYP2J2 in liver microsomes were evaluated and then applied to an in vitro-in vivo static scaling model to estimate the contribution of each isozyme, as a function of CYP abundance, activity, and genotype. Disposition of the CYP2J2- specific metabolite was also evaluated in vivo. In plasma, metabolite abundance was well above previously reported levels with circulating concentrations measured at 2μM for the main hydroxylisopropyl metabolite. Ritonavir and metabolite plasma profiles were simulated using Simcyp®. A modest (2-6%) contribution of CYP2J2 to ritonavir clearance is predicted which increases to more than 20% in subjects carrying CYP2D6 poor metabolizer polymorphisms and CYP3A4 irreversible inhibition. These results indicate that minor drug metabolizing enzymes could become quantitatively important in RTV clearance if main metabolic pathways are impeded.
    Biochemical Pharmacology 06/2014; DOI:10.1016/j.bcp.2014.06.020 · 4.65 Impact Factor
  • The Journal of Urology 04/2014; 191(4):e383. DOI:10.1016/j.juro.2014.02.1075 · 3.75 Impact Factor
  • The Journal of Urology 04/2014; 191(4):e382. DOI:10.1016/j.juro.2014.02.1074 · 3.75 Impact Factor
  • Source
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    ABSTRACT: Printable multi-marker biochips that enable simultaneous quantitative detection of multiple target biomarkers in point-of-care and resource-limited settings are a holy grail in the field of biodiagnostics. However, preserving the functionality of biomolecules, which are routinely employed as recognition elements, during conventional printing approaches remains challenging. In this article, we introduce a simple yet powerful approach, namely plasmonic calligraphy, for realizing multiplexed label-free bioassays. Plasmonic calligraphy involves a regular ballpoint pen filled with biofunctionalized gold nanorods as plasmonic ink for creating isolated test domains on paper substrates. Biofriendly plasmonic calligraphy approach serves as a facile method to miniaturize the test domain size to few mm(2), which significantly improves the sensitivity of the plasmonic biosensor compared to bioplasmonic paper fabricated using immersion approach. Furthermore, plasmonic calligraphy also serves as a simple and efficient means to isolate multiple test domains on a single test strip, which facilitates multiplexed biodetection and multi-marker biochips. Plasmonic calligraphy, which can be potentially automated by implementing with a robotic arm, serves as an alternate path forward to overcome the limitations of conventional ink-jet printing.
    Biosensors & Bioelectronics 03/2014; 59C:208-215. DOI:10.1016/j.bios.2014.03.043 · 6.45 Impact Factor
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    ABSTRACT: Codeine is bioactivated to morphine, a strong opioid agonist, by the hepatic cytochrome P450 2D6 (CYP2D6); hence, the efficacy and safety of codeine are governed by CYP2D6 activity. Polymorphisms are a major cause of CYP2D6 variability. We summarize evidence from the literature supporting this association and provide therapeutic recommendations for codeine based on CYP2D6 genotype. This document is an update to the 2012 Clinical Pharmacogenetics Implementation Consortium (CPIC) guidelines for CYP2D6 genotype and codeine therapy.
    Clinical Pharmacology &#38 Therapeutics 01/2014; 95(4-4):376-82. DOI:10.1038/clpt.2013.254 · 7.39 Impact Factor
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    ABSTRACT: Printable multi-marker biochips that enable simultaneous quantitative detection of multiple target biomarkers in point-of-care and resource-limited settings are a holy grail in the field of biodiagnostics. However, preserving the functionality of biomolecules, which are routinely employed as recognition elements, during conventional printing approaches remains challenging. In this article, we introduce a simple yet powerful approach, namely plasmonic calligraphy, for realizing multiplexed label-free bioassays. Plasmonic calligraphy involves a regular ballpoint pen filled with biofunctionalized gold nanorods as plasmonic ink for creating isolated test domains on paper substrates. Biofriendly plasmonic calligraphy approach serves as a facile method to miniaturize the test domain size to few mm2, which significantly improves the sensitivity of the plasmonic biosensor compared to bioplasmonic paper fabricated using immersion approach. Furthermore, plasmonic calligraphy also serves as a simple and efficient means to isolate multiple test domains on a single test strip, which facilitates multiplexed biodetection and multi-marker biochips. Plasmonic calligraphy, which can be potentially automated by implementing with a robotic arm, serves as an alternate path forward to overcome the limitations of conventional ink-jet printing.
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    ABSTRACT: We demonstrate that gold nanocages (AuNCs) with built-in artificial antibodies enable the detection of kidney injury biomarker from synthetic urine down to a concentration of 25 ng/ml. Molecularly imprinted AuNCs exhibit excellent selectivity against numerous interfering urinary proteins and remarkable stability over a wide range of pH and specific gravity.
    Journal of Materials Chemistry 11/2013; 2(2). DOI:10.1039/C3TB21551B · 7.44 Impact Factor
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    ABSTRACT: To evaluate the trends in urine aquaporin-1 (AQP1) and perilipin 2 (PLIN2) concentrations in patients with clear cell and papillary renal cell carcinoma (RCC), we determined the relationship between the urine concentration of these biomarkers and tumor size, grade, and stage. The biomarker concentrations were determined by sensitive and specific Western blot procedures normalized to the urine creatinine excretion. The analysis included 61 patients undergoing partial or radical nephrectomy for clear cell or papillary RCC and 43 age- and sex-matched control patients. Relationships between urine biomarker concentrations and tumor size, stage, and grade were assessed. Patients with RCC had 35-fold and 9-fold higher median urinary AQP1 and PLIN2 concentrations, respectively, compared with controls. Both tumor markers decreased after tumor resection to concentrations equivalent to those of controls. The sensitivity and specificity were both 100% for AQP1 and 92% and 100%, respectively, for PLIN2. A significant linear correlation was found between the tumor size and the prenephrectomy AQP1 (Spearman coefficient 0.78, P <.001) and PLIN2 (Spearman coefficient 0.69, P <.001) concentrations. A correlation was found for both markers with tumor stage (overall P = .030), when the stage was dependent primarily on the tumor size (stages T1 and T2), but not with stage T3, which reflected extrarenal spread. Neither marker showed a significant correlation with tumor grade. AQP1 and PLIN2 were significantly increased in patients with clear cell and papillary RCC compared with controls. The preoperative urinary concentrations of these markers reflected the tumor size and stage.
    Urology 11/2013; DOI:10.1016/j.urology.2013.09.026 · 2.13 Impact Factor
  • Evan D Kharasch, Kristi Stubbert
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    ABSTRACT: Plasma concentrations of orally administered methadone are reduced by the HIV protease inhibitor combination ritonavir/lopinavir, but the mechanism is unknown. Methadone metabolism, clearance and drug interactions have been attributed to CYP3A4, but this remains controversial. This investigation assessed effects of acute (2d) and steady-state (2 weeks) ritonavir/lopinavir on intravenous and oral methadone metabolism and clearance, hepatic and intestinal CYP3A4/5 activity (using the probe substrate intravenous and oral alfentanil), and intestinal transporter activity (using oral fexofenadine), in healthy volunteers. Plasma and urine concentrations of methadone and metabolite enantiomers, and other analytes, were determined by mass spectrometry. Acute and chronic ritonavir/lopinavir reduced plasma methadone enantiomer concentrations in half, with an average 2.6- and 1.5-fold induction of systemic and apparent oral methadone clearances. Induction was attributable to stereoselectively increased hepatic methadone N-demethylation, hepatic extraction, and hepatic clearance, and there was a strong correlation between methadone N-demethylation and clearance. Methadone renal clearance was unchanged. Alfentanil systemic clearance and hepatic extraction, apparent oral clearance, and intestinal extraction were reduced to 25%, 16% and 35% of control, indicating strong inhibition of hepatic and intestinal CYP3A activities. Ritonavir/lopinavir (acute>chronic) increased fexofenadine exposure, suggesting intestinal P-glycoprotein inhibition. There was no correlation between methadone clearance and CYP3A activity. Acute and steady-state ritonavir/lopinavir stereoselectively induced methadone N-demethylation and clearance, despite significant inhibition of hepatic and intestinal CYP3A activity. Ritonavir/lopinavir inhibited intestinal transporters activity, but had no effect on methadone bioavailability. These results do not support a significant role for CYP3A or ritonavir/lopinavir-inhibitable intestinal transporters in single-dose methadone disposition.
    Drug metabolism and disposition: the biological fate of chemicals 09/2013; 41(12). DOI:10.1124/dmd.113.053991 · 3.33 Impact Factor
  • Karen J Regina, Evan D Kharasch
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    ABSTRACT: A new method using ultra-fast liquid chromatography and tandem mass spectrometry (UFLC-MS/MS) was developed for the simultaneous determination of buprenorphine and the metabolites norbuprenorphine, buprenorphine-3β-glucuronide, and norbuprenorphine-3β-glucuronide in plasma and urine. Sample handling, sample preparation and solid-phase extraction procedures were optimized for maximum analyte recovery. All four analytes of interest were quantified by positive ion electrospray ionization tandem mass spectrometry after solid-phase microextraction. The lower limits of quantification in plasma were 1pg/mL for buprenorphine and buprenorphine glucuronide, and 10pg/mL for norbuprenorphine and norbuprenorphine glucuronide. The lower limits of quantitation in urine were 10pg/mL for buprenorphine, norbuprenorphine and their glucuronides. Overall extraction recoveries ranged from 68-100% in both matrices. Interassay precision and accuracy was within 10% for all four analytes in plasma and within 15% in urine. The method was applicable to pharmacokinetic studies of low-dose buprenorphine.
    Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 09/2013; 939C:23-31. DOI:10.1016/j.jchromb.2013.09.004 · 2.69 Impact Factor

Publication Stats

7k Citations
1,312.54 Total Impact Points

Institutions

  • 2007–2015
    • Washington University in St. Louis
      • Department of Anesthesiology
      San Luis, Missouri, United States
  • 2009
    • Saint Louis University
      Сент-Луис, Michigan, United States
  • 1988–2008
    • University of Washington Seattle
      • • Department of Medicinal Chemistry
      • • Department of Pharmaceutics
      • • Department of Psychiatry and Behavioral Sciences
      Seattle, Washington, United States
  • 2006
    • Temple University
      • Department of Pharmacology
      Filadelfia, Pennsylvania, United States
  • 2005
    • Norwegian University of Science and Technology
      • Department of Circulation and Medical Imaging
      Nidaros, Sør-Trøndelag, Norway
  • 2004
    • Purdue University
      ウェストラファイエット, Indiana, United States
    • Ankara University
      • Department of Pharmaceutical Chemistry
      Ankara, Ankara, Turkey
  • 2002
    • St. Jude Children's Research Hospital
      • Department of Pharmaceutical Sciences
      Memphis, Tennessee, United States
  • 1997–1999
    • VA Puget Sound Health Care System
      Washington, Washington, D.C., United States
  • 1998
    • Medical College of Wisconsin
      • Department of Anesthesiology
      Milwaukee, Wisconsin, United States