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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 35 (1994), S. 213-218 
    ISSN: 1432-0843
    Keywords: Key words Anthracyclines ; Daunorubicin ; Daunorubicinol ; Pharmacokinetics ; Rat ; Tissue concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Recent evidence suggests that 13-hydroxy metabolites of anthracyclines may contribute to cardiotoxicity. This study was designed to determine the pharmacokinetics of daunorubicin and the 13-hydroxy metabolite daunorubicinol in plasma and tissues, including the heart. Fisher 344 rats received 5 mg kg–1 daunorubicin i.v. by bolus injection. Rats were killed at selected intervals for up to 1 week after daunorubicin administration for determination of concentrations of daunorubicin and daunorubicinol in the plasma, heart, liver, kidney, lung, and skeletal muscle. Peak concentrations of daunorubicin were higher than those of daunorubicinol in the plasma (133 ± 7 versus 36 ± 2 ng ml–1; P 〈 0.05), heart (15.2 ± 1.4 versus 3.4 ± 0.4 μg g–1; P 〈 0.05), and other tissues. However, the apparent elimination half-life of daunorubicinol was longer than that of daunorubicin in most tissues, including the plasma (23.1 versus 14.5 h) and heart (38.5 versus 19.3 h). In addition, areas under the concentration/time curves (AUC∞) obtained for daunorubicinol exceeded those found for daunorubicin in almost all tissues, with the ratios being 1.9 in plasma and 1.7 in the heart. The ratio of daunorubicinol to daunorubicin concentrations increased dramatically with time from 〈1 at up to 1 h to 87 at 168 h in cardiac tissue. Thus, following daunorubicin injection, cumulative exposure (AUC∞) to daunorubicinol was greater than that to daunorubicin in the plasma and heart. If daunorubicinol has equivalent or greater potency than daunorubicin in causing impairment of myocardial function, it may make an important contribution to the pathogenesis of cardiotoxicity.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Cancer chemotherapy and pharmacology 35 (1995), S. 213-218 
    ISSN: 1432-0843
    Keywords: Anthracyclines ; Daunorubicin ; Daunorubicinol ; Pharmacokinetics ; Rat ; Tissue concentrations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Recent evidence suggests that 13-hydroxy metabolites of anthracyclines may contribute to cardiotoxicity. This study was designed to determine the pharmacokinetics of daunorubicin and the 13-hydroxy metabolite daunorubicinol in plasma and tissues, including the heart. Fisher 344 rats received 5 mg kg−1 daunorubicin i.v. by bolus injection. Rats were killed at selected intervals for up to 1 week after daunorubicin administration for determination of concentrations of daunorubicin and daunorubicinol in the plasma, heart, liver, kidney, lung, and skeletal muscle. Peak concentrations of daunorubicin were higher than those of daunorubicinol in the plasma (133±7 versus 36±2 ng ml−1;P〈0.05), heart (15.2±1.4 versus 3.4±0.4 μg g−1;P〈0.05), and other tissues. However, the apparent elimination half-life of daunorubicinol was longer than that of daunorubicin in most tissues, including the plasma (23.1 versus 14.5 h) and heart (38.5 versus 19.3 h). In addition, areas under the concentration/time curves (AUC∞) obtained for daunorubicinol exceeded those found for daunorubicin in almost all tissues, with the ratios being 1.9 in plasma and 1.7 in the heart. The ratio of daunorubicinol to daunorubicin concentrations increased dramatically with time from 〈1 at up to 1 h to 87 at 168 h in cardiac tissue. Thus, following daunorubicin injection, cumulative exposure (AUC∞) to daunorubicinol was greater than that to daunorubicin in the plasma and heart. If daunorubicinol has equivalent or greater potency than daunorubicin in causing impairment of myocardial function, it may make an important contribution to the pathogenesis of cardiotoxicity.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0843
    Keywords: Key words Anthracyclines ; Daunorubicin ; Daunorubicinol ; Pharmacokinetics ; Rat ; Aging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Age-related differences in pharmacokinetics may be important in determining altered anthracycline cardiotoxicity in the senescent rat and also in older humans. This study examined the effect of aging on daunorubicin pharmacokinetics in the Fischer 344 rat. Daunorubicin 7.5 mg/kg was administered i.v. to 6-and 24-month-old male Fischer 344 rats and plasma and tissue sampling was performed over 168 h for assay of daunorubicin and daunorubicinol concentrations by high-performance liquid chromatography. Systemic clearance of daunorubicin was decreased in older compared to younger animals (56±4 versus 202±17 ml min-1 kg-1; P〈0.05). In addition, the area under the plasma daunorubicinol concentration/time curve was significantly increased in older rats. In the heart, the area under the concentration/time curve was significantly increased in senescence both in the case of daunorubicin (201±12 versus 86±4 μg h g-1; P〈0.05) and daunorubicinol (1347±118 versus 182±4 μg h g-1; P〈0.05). Furthermore, the peak mean concentrations of daunorubicin were increased in older compared to younger rats both in plasma (1078±82 versus 663±66 ng ml-1; P〈0.05) and in heart (27±1 versus 10±1 μg g-1; P〈0.05). This also was true for daunorubicinol in plasma (284±39 versus 168±27 ng ml-1; P〈0.05) and in myocardium (8.6±0.6 versus 2.4±0.2 μg g-1; P〈0.05). Following daunorubicin injection, the ratio of daunorubicinol to daunorubicin concentrations in tissues increased with time, particularly in plasma and heart in senescent rats. Thus, there are significant age-related changes in daunorubicin and daunorubicinol kinetics in the rat that could alter susceptibility to acute systemic toxicity and to chronic cardiotoxicity.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Malnutrition involving protein deficiency, which commonly occurs in cancer patients receiving anthracycline treatment, is considered to be a risk factor for the development of cardiotoxicity. Protein deficiency has been shown to impair the metabolism of drugs such as theophylline and acetaminophen. If protein deficiency also impairs anthracycline metabolism, it could explain at least in part the enchanced anthracycline toxicity associated with malnutrition. We tested this idea by determining the effect of a low- protein, isocaloric diet on doxorubicin pharmacokinetics in rabbits. The animals were randomized into two groups for 8–12 weeks. Rabbits in group 1 received a low-protein (5%), isocaloric diet, whereas those in group 2 received a normal-protein (15%) diet. Both groups (group 1,n=15; group 2,n=14) were given 5 mg/kg doxorubicin by i.v. bolus. After doxorubicin injection, blood samples were obtained over the next 52 h for the measurement of doxorubicin and doxorubicinol plasma concentrations by high-performance liquid chromatography (HPLC) with fluorometric detection. The low-protein diet significantly decreased doxorubicin clearance (48±3 vs 59±4 ml min−1 kg−1;P〈0.05), prolonged the terminal climination half-life (28±2 vs 22±2 h;P〈0.05), and increased the area under the plasma concentration/time curve extrapolated to infinity (1722±122 vs 1405±71 ng h ml−1;P〈0.05) as compared with the values determined for rabbits fed the standard rabbit chow (15% protein). The volume of distribution for doxorubicin was not altered by the low-protein diet. In addition, in rabbits fed the the low-portein diet, the terminal elimination half-life of the alcohol metabolite, doxorubicinol was prolonged (52±5 vs 40±2 h;P〈0.05). Thus, a low-protein diet causes a reduction in the ability of rabbits to eliminate doxorubicin and possibly its alcohol metabolite doxorubicinol. If a similar alteration in anthracycline pharmacokinetics occurs in malnourished cancer patients, this phenomenon may contribute to their increased risk of developing cardiotoxicity associated with anthracycline therapy.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-0843
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Cumulative dose-related, chronic cardiotoxicity is a serious clinical complication of anthracycline therapy. Clinical and animal studies have demonstrated that continuous infusion, compared to bolus injection of doxorubicin, decreases the risk of cardiotoxicity. Continuous infusion of doxorubicin may result in decreased cardiac tissue concentrations of anthracyclines, including the primary metabolite doxorubicinol, which may also be an important contributor to cardiotoxicity. In this study, doxorubicin and doxorubicinol plasma pharmacokinetics and tissue concentrations were compared in New Zealand white rabbits following intravenous administration of doxorubicin (5 mg·kg−1) by bolus and continuous infusion. Blood samples were obtained over a 72-h period after doxorubicin administration to determine plasma doxorubicin and doxorubicinol concentrations. Rabbits were killed 7 days after the completion of doxorubicin administration and tissue concentrations of doxorubicin and doxorubicinol in heart, kidney, liver, and skeletal muscle were measured. In further experiments, rabbits were killed 1 h after bolus injection of doxorubicin and at the completion of a 24-h doxorubicin infusion (anticipated times of maximum heart anthracycline concentrations) to compare cardiac concentrations of doxorubicin and doxorubicinol following both methods of administration. Peak plasma concentrations of doxorubicin (1739±265 vs 100±10 ng·ml−1) and doxorubicinol (78±3 vs 16±3 ng·ml−1) were significantly higher following bolus than infusion dosing. In addition, elimination half-life of doxorubicinol was increased following infusion. However, other plasma pharmacokinetic parameters for doxorubicin and doxorubicinol, including AUC∞, were similar following both methods of doxorubicin administration. Peak left ventricular tissue concentrations of doxorubicin (16.92±0.9 vs 3.59±0.72 μg·g−1 tissue;P〈0.001) and doxorubicinol (0.24±0.02 vs 0.09±0.01 μg·g−1 tissue;P〈0.01) following bolus injection of doxorubicin were significantly higher than those following infusion administration. Tissue concentrations of parent drug and metabolite in bolus and infusion groups were similar 7 days after dosing. The results suggest that cardioprotection following doxorubicin infusion may be related to attenuation of the peak plasma or cardiac concentrations of doxorubicin and/or doxorubicinol.
    Type of Medium: Electronic Resource
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