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  • 1
    ISSN: 1569-8041
    Keywords: melanoma ; pharmacodynamics ; pharmacokinetics ; temozolomide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The DNA repair protein O6-alkylguanine-DNA alkyl transferase (AT) mediates resistance to chloroethylnitrosoureas. Agents depleting AT such as DTIC and its new analogue temozolomide (TMZ) can reverse resistance to chloroethylnitrosoureas. We report the results of a dose finding study of TMZ in association with fotemustine. Patients and methods: Twenty-four patients with metastatic melanoma or recurrent glioma were treated with escalating dose of oral or intravenous TMZ ranging from 300 to 700 mg/m2, divided over two days. Fotemustine 100 mg/m2 was given intravenously on day 2, 4 hours after TMZ. AT depletion was measured in peripheral blood mononuclear cells (PBMCs) and in selected cases in melanoma metastases and was compared to TMZ pharmacokinetics. Results: The maximum tolerated dose (MTD) of TMZ was 400 mg/m2 (200 mg/m2/d) when associated with fotemustine the 2nd day with myelosuppression as dose limiting toxicity. The decrease of AT level in PBMCs was progressive and reached 34% of pretreatment values on day 2. There was however wide interindividual variability. AT reduction was neither dose nor route dependent and did not appear to be related to TMZ systemic exposure (AUC). In the same patients, AT depletion in tumour did not correlate with the decrease of AT observed in PBMCs. Conclusions: PBMCs may not be used as a surrogate of tumour for AT depletion. Further study should concentrate on the pharmacokinetic pharmacodynamic relationship in tumour to provide the basis for individually tailored therapy.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1569-8041
    Keywords: docetaxel ; doxorubicin ; interaction ; mice ; paclitaxel ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Background: The combination of doxorubicin (Dx) with paclitaxel or docetaxel is clinically effective but there are concerns regarding the higher incidence of cardiotoxicity of the combination compared with Dx alone. The mechanism of the increased toxicity is still unclear. Purpose: To assess whether there is a pharmacokinetic interaction between paclitaxel, docetaxel or their vehicles and Dx in mice. Materials and methods: CDF1 male mice were treated with Dx either alone (10 mg/kg i.v.) or in combination with paclitaxel (25 mg/kg) or docetaxel (25 mg/kg) or their vehicles, i.e., cremophor-ethanol-glucose (cremophor) or polysorbate80-ethanol-glucose (polysorbate). Four mice were killed 4, 8 or 24 hours after Dx in each experimental group and Dx was assayed in serum and in heart, liver, kidney and spleen by HPLC. Results: Four hours after treatment the concentrations of Dx in heart, liver and kidney were much higher in mice concomitantly treated with paclitaxel, docetaxel (dissolved in either cremophor or polysorbate) and cremophor. At subsequent times the differences were modest and only reached statistical significance in a few cases. Dx metabolites were modified by concomitant treatment with taxanes or their vehicles. In particular, the levels of Dx aglycone in liver and kidney were significantly lower in mice treated with the combination than in mice given Dx alone. Conclusions: paclitaxel, docetaxel and cremophor when given together with Dx modify its distribution and metabolism, increasing Dx levels in many tissues including the heart. This might have some bearing on the toxicity of regimens in which Dx is combined with taxanes.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 22 (1993), S. 351-357 
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We used gas chromatography/mass spectrometry to identify and quantitate some aphidicolin metabolites in plasma and urine of patients receiving aphidicolin-17-glycinate. The major metabolite found in plasma was 3-ketoaphidicolin, present at about one thent the concentrations of aphidicolin. 3-Ketoaphidicolin undergoes dehydroxymethylation to give 18-nor-3-ketoaphidicolin. This metabolite was also found in plasma and its concentration reached a maximum of 1% of aphidicolin.Small amounts of aphidicolin and 3-ketoaphidicolin were found free in urine but almost all of the drug was conjugated to glucuronic acid, as shown by mass spectrometric analysis of urine extracts and by enzymatic digestion with β-glucoronidase followed by gas chromatographic/mass spectrometric analysis.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 10 (1983), S. 485-488 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: High pressure liquid chromatography was used in combination with mass spectrometry to confirm that the main products of in vitro metabolism of 1-(4-acetylphenyl)-3,3-dimethyltriazene are 1-(4-acetylphenyl-3-methyltriazene and 4-aminoacetophenone. In addition a novel metabolite, 1-[4-(1-hydroxyethyl)-phenyl]-3,3-dimethyltriazene, possessing antitumour activity similar to the parent drug, was identified.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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