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  • 1
    Electronic Resource
    Electronic Resource
    The Use of Human Hepatocytes to Select Compounds Based on Their Expected Hepatic Extraction Ratios in Humans (1997)
    Springer
    Pharmaceutical research 14 (1997), S. 152-155 
    Details
    ISSN: 1573-904X
    Keywords: human hepatocytes ; extraction ratio ; pharmacokinetics ; clearance ; in vitro models
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Purpose. The present investigation retrospectively evaluates the use of human hepatocytes to classify compounds into low, intermediate or high hepatic extraction ratio in man. Methods. A simple approach was used to correlate the in vivo hepatic extraction ratio of a number of compounds in man (literature and in-house data) with the corresponding in vitro clearance which was determined in human hepatocytes. The present approach assumes that, for compounds eliminated mainly through liver metabolism, intrinsic clearance is the major determinant for their in vivo hepatic extraction ratio and subsequently their bioavailability in man. The test compounds were selected to represent a broad range of extraction ratios and a variety of metabolic pathways. Results. The present data show that in vitro clearances in human hepatocytes are predictive for the hepatic extraction ratios in vivo in man. Most of the test compounds (n = 19) were successfully classified based upon human hepatocyte data into low, intermediate or high hepatic extraction compounds, i.e. compounds with potential for high, intermediate or low bioavailabilities in humans. Conclusions. The present approach, validated so far with 19 test compounds, appears to be a valuable tool to screen for compounds with respect to liver first-pass metabolism at an early phase of drug discovery.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1012036324237
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  • 2
    Electronic Resource
    Electronic Resource
    Quantitative analysis of 5-fluorouracil and 5,6-dihydrofluorouracil in plasma by gas chromatography mass spectrometry (1982)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 9 (1982), S. 336-339 
    Details
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 5-Fluorouracil and 5,6-dihydro-5-fluorouracil were analysed in the plasma of patients by combined gas chromatography mass spectrometry. 5-Bromouracil was the internal standard. After extraction from plasma with an isopropanol-diethyl ether mixture (20/80) the components were pentylated and the derivatives produced extracted into diethyl ether. Electron impact mass spectrometry was used for the simultaneous quantitative determinations of 5-fluorouracil and 5,6-dihydro-5-fluorouracil (detection limit 10 ng mI-1 5-fluorouracil, 80 ng mI-1 5,6-dihydro-5-fluorouracil). Chemical ionization was utilized to measure 5,6-dihydro-5-fluorouracil concentrations 〈80 ng mI-1 (sensitivity 10 ng mI-1). The biological applicability of these two techniques was demonstrated by analysing plasma samples from patients after administration of 5-fluorouracil or 5′-deoxyfluorouridine by intravenous injections and infusions.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200090806
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  • 3
    Electronic Resource
    Electronic Resource
    Determination of flurazepam and its hydroxyethyl and dealkyl metabolites by some packed and capillary ECD-GLC methods: Application to pharmacokinetic studies (1984)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 7 (1984), S. 258-264 
    Details
    ISSN: 0935-6304
    Keywords: Gas-liquid chromatography ; Packed and capillary columns ; Plasma anaysis ; Pharmacokinetic studies ; Benzodiazepines ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A sensitive gas-liquid chromatographic assay was developed for plasma determinations of flurazepam (F), N1-desalkylflurazepam (DF), and N1-hydroxyethylflurazepam (HF). The internal standards used were delorazepam for F and DF and 1 ã-hydroxymidazolam for HF. Following extraction and derivatization for HF, these compounds were analyzed by ECD-GLC, using either glass packed columns (poly A 103 for F and DF, OV 225 for HF) or CP-Sil 5 capillary columns for DF and HF. The detection limit of the packed-column assay was approximately 3ng/ml for HF and DF, and 5ng/ml for F; with capillary GLC analysis, the sensitivity limit for HF and DF was lower than 1 ng/ml. These methods were used for pharmacokinetic investigations after i. v. administration of these compunds.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240070505
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