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  • CYP3A  (1)
  • Cytochrom-P450  (1)
  • antiarrhythmic drug  (1)
  • 1
    ISSN: 1432-1912
    Keywords: Key words Cytochrome P 450 ; CYP3A ; Human lung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have previously demonstrated expression of cytochrome P 450 3A (CYP3A) protein in pulmonary carcinomas and surrounding normal tissue, using immunohistochemistry. These results suggested that different CYP3A enzymes may be expressed in normal and tumour tissue. Therefore, the aim of the present study was to identify specific CYP3A enzymes expressed in normal human lung and lung tumours. Both normal lung tissue and tumour tissue from eight patients was analyzed for CYP3A4, CYP3A5 and CYP3A7 mRNA using a specific RT-PCR (reverse transcriptase-polymerase chain reaction) method. Identical samples were subjected to immunohistochemical analysis of CYP3A protein. CYP3A5 was the major enzyme of the CYP3A subfamily present at the mRNA level in both normal human lung and lung tumours. CYP3A5 mRNA was detected in normal lung tissue in all eight cases and in tumour tissue in four cases. CYP3A7 mRNA was detected in five cases in normal tissue and in one tumour. Notably, no CYP3A4 mRNA was found in any of the samples. Immunohistochemical staining for CYP3A protein was found in normal lung tissue in each case. Interestingly, all pulmonary carcinomas showed immunostaining for CYP3A, while mRNA for CYP3A enzymes was found in only four cases. In summary, our study indicates a specific expression pattern of the members of the CYP3A subfamily in normal human lung and lung tumours. These findings have potential clinical significance, since it has been recently shown that CYP3A5 catalyzes the activation of the anticancer pro-drugs cyclophosphamide and ifosfamide. Thus, local activation of these agents may take place in pulmonary carcinomas and surrounding normal tissues.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: Propafenone ; Renal failure ; glucuronides ; age ; antiarrhythmic drug ; plasma levels ; stereoisomers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The aim of this study was to investigate the disposition of propafenone and its Phase I and II metabolites in relation to kidney function under steady-state conditions. The mechanism of the renal handling of propafenone glucuronides (filtration, secretion) was also examined. Racemic (R/S) propafenone was administered to 7 young volunteers, to 5 older patients with a normal glomerular filtration rate and to 4 patients with chronic renal failure. No difference was found in the plasma concentrations of propafenone and 5-hydroxypropafenone between the three groups. The propafenone glucuronide (PPFG) concentration was elevated in the older compared to the younger subjects (S-PPFG: 544 vs. 222 nmol · ml−1 · mol−1; R-PPFG: 576 vs. 304 nmol · ml−1 · mol−1). Although Glomerular filtration rate did not differ, the renal clearance of propafenone glucuronides was reduced in the former group, which could be attributed to their impaired renal secretion. A dramatic increase in propafenone glucuronide concentration was observed in the patients with renal failure (S-PPFG: 2783 nmol · ml−1 · mol−1; R-PPFG: 7340 nmol · ml−1 · mol−1). In summary, the disposition of propafenone and of its active metabolite 5-hydroxypropafenone was not affected by kidney dysfunction, indicating that no dose adjustment is necessary in patients with renal failure. The accumulation of drug glucuronides in older patients with apparently normal kidney function should be taken into account as a possible factor modifying drug therapy.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Der Internist 41 (2000), S. 338-343 
    ISSN: 1432-1289
    Keywords: Schlüsselwörter ; Arzneimittelinteraktionen ; Cytochrom-P450 ; Transporter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zum Thema Die klinische Relevanz von Arzneimittelinteraktionen zeigt sich besonders in der internistischen Praxis, wo ein hoher Anteil der Patienten mehr als ein Arzneimittel gleichzeitig verordnet bekommt. Der vorliegende Artikel beschreibt zwei wesentliche Mechanismen, die bei dem Auftreten von Arzneimittelinteraktionen eine Rolle spielen können. Besondere Bedeutung für die Praxis haben zum einen die metabolischen Wechselwirkungen, die immer dann auftreten, wenn sich zwei gleichzeitig gegebene Arzneimittel in ihrem Stoffwechsel gegenseitig beeinflussen. Daneben soll auf die erst seit jüngerer Zeit bekannte Rolle von Transportern (P-Glykoprotein), die insbesondere die Resorption von Arzneimitteln beeinflussen können, eingegangen werden. Ziel dieser Übersicht ist es, die klinische Relevanz von Arzneistoffinteraktionen zu unterstreichen und vor dem Hintergrund neuer Erkenntnisse die Vorhersagbarkeit von Interaktionen zu verbessern und damit die Therapiesicherheit zu erhöhen.
    Type of Medium: Electronic Resource
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