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  • 1
    Electronic Resource
    Electronic Resource
    Radioimmunoassay of propranolol (1983)
    s.l. : American Chemical Society
    Analytical chemistry 55 (1983), S. 1572-1575 
    Details
    ISSN: 1520-6882
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac00260a028
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  • 2
    Electronic Resource
    Electronic Resource
    Influence of food on the intravenous and oral dose kinetics of propranolol in the dog (1985)
    Springer
    Journal of pharmacokinetics and pharmacodynamics 13 (1985), S. 229-241 
    Details
    ISSN: 1573-8744
    Keywords: food effects ; propranolol ; kinetics ; dogs ; oral and intravenous doses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The intravenous and oral dose kinetics of propranolol were studied in the dog both in a fasted state and immediately after a meal consisting of 100 g of cooked beef liver. Fifty ΜCi of3H-propranolol was administered intravenously simultaneously with a 40-mg oral dose of unlabeled propranolol. Plasma3H-propranolol was measured by specific extraction and liquid scintillation spectrometry, and unlabeled plasma propranolol was determined by gas chromatography-mass spectrometry. Feeding significantly reduced (25%) the elimination half-life and increased (52%) the systemic clearance of intravenous propranolol. The increase in the systemic clearance of propranolol after feeding was mostly due to an increase (60%) in apparent hepatic blood flow, which appeared to remain elevated for 5–7 hr. The meal had no influence on the apparent volume of distribution or plasma binding. Feeding did not affect the area under the concentration-time curve of oral propranolol, but significantly delayed the rate of oral propranolol absorption, shifting the time to reach peak plasma levels from 60 to 158 min. The results of this study suggest that feeding alters the disposition of propranolol in the dog by producing a sustained increase in hepatic blood flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01065654
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  • 3
    Electronic Resource
    Electronic Resource
    Induction of UDP-Glucuronosyl-Transferase by the Flavonoids Chrysin and Quercetin in Caco-2 Cells (2000)
    Springer
    Pharmaceutical research 17 (2000), S. 21-26 
    Details
    ISSN: 1573-904X
    Keywords: flavonoids ; chrysin ; quercetin ; induction ; glucuronidation ; UDP-glucuronosyltransferase ; Caco-2 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. Dietary flavonoids have been reported to be potent inhibitorsof drug metabolizing enzymes. In the present study we examined theinducing effect of three of these compounds, chrysin, quercetin andgenistein, on UDP-glucuronosyltransferase (UGT) in the humanintestinal cell line Caco-2. Methods. The induction of UGT by flavonoid pretreatment was studiedboth in the intact cells and cell homogenates, measured as theglucuronidation of chrysin, and by immunoblot analysis of the UGT 1A protein. Results. Exposure of Caco-2 cells to 50 μM chrysin resulted in a3.8-fold increase in chrysin glucuronidation in intact cells (p 〈 0.0001)with a 38% decrease in sulfation (p 〈 0.01). In the cell homogenatethe induction was much larger, 14-fold. The induction was slow todevelop with maximum induction after 3–4 days. Interestingly, theisoflavonoid genistein was without effect. Immunoblot analysis ofCaco-2 cell microsomes with a UGT1A subfamily-selective antibodyshowed a markedly increased band at about 59 kDa, consistent withinduction of one or more UGT1A isoforms. A 5-week exposure ofCaco-2 cells to low concentrations (10 μM) of chrysin or quercetinalso showed markedly increased glucuronidation activity. Conclusions. Diet-mediated induction of intestinal UGT may beimportant for the bioavailability of carcinogens and other toxicchemicals as well as therapeutic drugs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007506222436
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  • 4
    Electronic Resource
    Electronic Resource
    Stereoselective sulfate conjugation of isoproterenol in humans: Comparison of hepatic, intestinal, and platelet activity (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 5 (1993), S. 602-609 
    Details
    ISSN: 0899-0042
    Keywords: phenol sulfotransferase ; β-agonist ; drug enantiomers ; stereospecific ; chiral ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The stereochemistry of sulfate conjugation of isoproterenol (ISO) was examined with human liver, intestine, and platelets as the phenolsulfotransferase (PST) enzyme source and PAP35S as the cosubstrate. With the hepatic cytosol, two distinct sulfation reactions were identified, a high affinity reaction (Km 5 to 50 μM) and a low affinity reaction (Km 360 to 2,900 μM). The efficiency of sulfation (Vmax/Km) for both reactions was 5-fold higher for (+)- than for (-)-ISO. When the hepatic PSTs were resolved by ionexchange chromatography, it could be shown that the high affinity reaction was catalyzed by the monoamine (M) form and the low affinity reaction by the phenol (P) form of PST. Only the high affinity (M form) sulfation was detected in the jejunal cytosol with a Vmax/Km value 6.1-fold higher for (+)- than for (-)-ISO. Finally the platelet, as a potentially useful model tissue, also demonstrated only the high affinity M form reaction with a Vmax/Km value 5.7-fold higher for (+)- than for (-)-ISO. In summary, this study has shown that sulfation of ISO by PSTs in various human tissues is stereoselective and favors the inactive (+)-enantiomer over the active (-)-enantiomer by about 5-fold, a finding which should be considered in the therapeutic use of chiral drugs cleared by sulfate conjugation. © 1993 Wiley-Liss, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530050807
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  • 5
    Electronic Resource
    Electronic Resource
    Enantioselective sulfation of β2-receptor agonists by the human intestine and the recombinant M-form phenolsulfotransferase (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 10 (1998), S. 800-803 
    Details
    ISSN: 0899-0042
    Keywords: β2-agonist drugs ; sulfotransferase ; M-form phenolsulfotransferase ; sulfation ; isoproterenol ; metaproterenol ; terbutaline ; albuterol ; salbutamol ; salmeterol ; formoterol ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The β2-receptor agonist class of drugs is metabolized in humans almost exclusively by sulfate conjugation. The objective of this investigation was to determine the influence of chemical structure on the stereoselectivity of the sulfoconjugation of these chiral drugs. The pure enantiomers of six β2-agonists, including those clinically most widely used, were all effectively sulfated both by the cytosol of the human intestine and the recombinant human M-form phenolsulfotransferase (PST). Whereas the apparent Km values (Km,app) for the sulfation of the individual drug enantiomers by the intestinal cytosol varied widely, ranging from 4.8 μM for (S)-isoproterenol to 889 μM for (S)-albuterol, these Km,app values were highly correlated with those obtained with M-PST (correlation coefficient 0.994). In contrast, the M-PST Vmax,app values were similar for all drug enantiomers, ranging from 276 to 914 pmol min-1 mg-1 protein, implying that substrate binding to M-PST by far is the main determinant of the sulfation activity. For isoproterenol, the Km,app for M-PST was 6.1 times higher for the active (R)- than for the inactive (S)-enantiomer. For other β2-agonists, the stereoselectivity decreased towards unity as the Km,app increased. However, for albuterol, containing a hydroxymethyl substituent at the aromatic ring, the stereoselectivity was dramatically reversed, with 10 times higher Km,app for the inactive (S)- than for the active (R)-enantiomer. Chirality 10:800-803, 1998. © 1998 Wiley-Liss, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stereoselective sulfation of terbutaline by the rat liver cytosol: evaluation of experimental approaches (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 121-126 
    Details
    ISSN: 0899-0042
    Keywords: stereoselective metabolism ; sulfate conjugation ; in vitro sulfation ; sympathomimetic amines ; chiral separation ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Little is known about the stereochemistry of sulfation of chiral phenolic drugs. In this study we examined several in vitro approaches to this question, using (+)-, (-)-, or (±)-terbutaline as the substrate and the rat liver cytosol as the phenolsulfotransferase enzyme source. The cosubstrate PAPS was either generated by the cytosol from inorganic sulfate and ATP or added to the cytosol. The intact sulfate conjugates formed were determined by HPLC. Using the PAPS generating system, which is best suited for the production of relatively large quantities of sulfate conjugates, with the individual enantiomers as substrates, (+)-terbutaline was conjugated to a much greater extent than (-)-terbutaline; the (+)/(-)-enantiomer ratio was 7.3 ± 0.3 (mean ± SE). When (±)-terbutaline was the substrate and chiral derivatization was employed to separate the sulfate enantiomers formed, a similar (+)/(-)-enantiomer ratio of 7.9 ± 0.2 was obtained. With PAP35S added to the cytosol, an approach best suited for kinetic studies, the substrate concentration dependence of sulfation could be determined. The Km app for this reaction was identical for (+)- and (-)-terbutaline. However, the Vmax app was 8.1 ± 0.4 times greater for (+)-terbutaline. This study for the first time shows enantioselectivity in sulfation of a chiral phenolic drug. The experimental approaches used should be valuable for human studies of stereoselectiven sulfation of terbutaline and other chiral drugs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010205
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  • 7
    Electronic Resource
    Electronic Resource
    Stereochemistry of tissue distribution of racemic propranolol in the dog (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Chirality 1 (1989), S. 192-196 
    Details
    ISSN: 0899-0042
    Keywords: propranolol enantiomers ; enantiomers ; propranolol ; β-receptor-blocking drugs ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Only limited information is available on the stereochemistry of the in vivo distribution of β-receptor-blocking drugs. In this study we determined the levels of the propranolol enantiomers in plasma, cerebrospinal fluid (CSF) and central nervous system (CNS), and peripheral tissues in the dog following an intravenous dose of a deuterium-labeled pseudoracemate. The appearance of the propranolol enantiomers in the CSF was rapid and nonstereoselective, with maximum concentrations reached at 15 min after dosing. The levels of the enantiomers in both CSF and plasma then declined in a parallel biphasic fashion, with a terminal t1/2 of about 125 min. Except for an early high CSF/plasma concentration ratio of 0.35, the CSF propranolol levels corresponded to the unbound concentration in plasma, CSF/plasma 0.20. All areas of the brain showed a similar uptake of propranolol, with a tissue concentration exceeding that in plasma about 10-fold during the terminal phase of elimination. The uptake of propranolol by peripheral tissues varied widely, ranging from a 50-fold accumulation by the lungs compared to plasma to no accumulation by adipose tissue. However, as for the CSF, there was no evidence of stereoselective uptake of propranolol by any CNS or peripheral tissue except for the liver. A significantly higher level of (+)- vs. (-)-propranolol in liver tissue presumably was a reflection of stereoselective hepatic metabolism of (-)-propranolol by this tissue. The slight stereoselectivity in plasma binding of propranolol known to exist in the dog had no significant influence on tissue or CSF distribution.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/chir.530010303
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  • 8
    Electronic Resource
    Electronic Resource
    Propranolol, alprenolol and oxprenolol metabolism in the dog. Identification of N-Methylated metabolites (1981)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 8 (1981), S. 78-84 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The metabolism of propranolol, alprenolol and oxprenolol was studied in the dog and rat; propranolol in five additional species, including man. Basic, phenolic and neutral metabolites were extracted from urine at pH 9.6 after enzymatic hydrolysis. Separation and identification of parent drug and seven metabolites each for propranolol, alprenolol and oxprenolol in the dog were accomplished by gas chromatography mass spectrometry as the trifluoroacetyl derivatives. A very uniform and predictable fragmentation pattern was observed for all 24 compounds. Seven new metabolites were identified. The metabolism of all three drugs was qualitatively the same, including N-dealkylation followed by N-methylation or deamination of the primary amines. The parent drugs as well as all of their sidechain metabolism products were also partially ring hydroxylated. N-Methylation was only found in the dog and is a minor metabolic pathway. The stereochemical composition of N-methyldesisopropylpropranolol and its immediate precursor N-desisopropylpropranolol showed a marked enrichment of the (+)-isomer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200080206
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  • 9
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    Cancer chemopreventive properties of orally bioavailable flavonoids—Methylated versus unmethylated flavones (2007)
    Elsevier
    Details
    Publication Date: 2007-05-01
    Print ISSN: 0006-2952
    Electronic ISSN: 1873-2968
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Published by Elsevier
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  • 10
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    Pharmacokinetic parameters obtained with racemates (1986)
    Cell Press
    Details
    Publication Date: 1986-01-01
    Print ISSN: 0165-6147
    Electronic ISSN: 1873-3735
    Topics: Biology , Medicine
    Published by Cell Press
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