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  • 1
    ISSN: 1432-1440
    Keywords: Polymorphic drug oxidation ; Metoprolol ; Propafenone ; Diltiazem ; Sparteine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 47-year-old patient suffering from coronary artery disease was admitted to the CCU in shock with IIIo AV block, severe hypotension, and impairment of ventricular function. One week prior to admission a therapy with standard doses of metoprolol (100 mg t.i.d. and then 100 mg b.i.d.) had been initiated. Two days before admission diltiazem (60 mg b.i.d.) was prescribed in addition. Analyses of a blood sample revealed unusually high plasma concentrations of metoprolol (〉 3000 ng/ml) and diltiazem (526 ng/ml). The patient recovered within 1 week following discontinuation of antianginal therapy. Three months later the patient was exposed to a single dose of metoprolol, diltiazem, propafenone (since he had received this drug in the past), and sparteine (as a probe for the debrisoquine/sparteine type polymorphism of oxidative drug metabolism). It was found that he was a poor metabolizer of all four drugs, indicating that their metabolism is under the same genetic control. Therefore, patients belonging to the poor-metabolizer phenotype of sparteine/debrisoquine polymorphism in drug metabolism, which constitutes 6.4% of the German population, may experience adverse drug reactions when treated with standard doses of one of these drugs alone. Moreover, the coadministration of these frequently used drugs is expected to be especially harmful in this subgroup of patients.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 62 (1984), S. 885-886 
    ISSN: 1432-1440
    Keywords: Cephalosporins ; Vitamin K1-epoxide ; Coumarin-like action
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In three patients treated with cephalosporins (one patient with latamoxef, two patients with cefazedone) vitamin K1 was injected to investigate whether this was followed by an increase in vitamin K1 2,3-epoxide plasma concentrations as compared to controls. Such a rise in K1-epoxide concentrations in the plasma can be demonstrated following treatment with coumarins. This reflects an inhibition of the vitamin K1-epoxide reductase in the liver. Coumarins are thought to induce hypoprothrombinaemia by such a mechanism. In all three patients we found a considerable increase in the vitamin K1-epoxide plasma concentrations following injection of 10 mg vitamin K1, whereas in normal subjects only traces of K1-epoxide could be detected (〈0.030 µg/ml). The K1-epoxide concentrations found in our three patients treated with cephalosporins were 0.12, 0.16 and 0.19 µg/ml, respectively. This indicates that latamoxef or cefazedone might reduce clotting factor synthesis by a coumarin-like mechanism of action in these patients. Although the effect of cephalosporins in enhancing vitamin K1-epoxide plasma concentrations is less than that of coumarins, it might cause severe hypoprothrombinaemia in the presence of latent vitamin K deficiency.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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