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  • Cotinine  (1)
  • pharmacokinetics  (1)
  • 1
    ISSN: 1432-1041
    Keywords: Key words Transdermal ; Nicotine ; Plasma concen-trations ; Cotinine ; Smoking cessation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: Interindividual variability in plasma concentrations of nicotine and its proximate metabolite, cotinine, is considerable during smoking and transdermal nicotine treatment, even among individuals taking in nominally similar doses of nicotine. This report explores the determinants of this variability and the utility of baseline (smoking) plasma concentrations to predict concentrations during transdermal nicotine treatment. Methods: Data were analysed from a smoking cessation study (n = 466), and from a pharmacokinetic study (n = 12). Multiple regression models examined the relationships of plasma concentrations to individual characteristics such as smoking pattern, absorbed dose of nicotine, and pharmacokinetic parameters. Results: Plasma concentrations of nicotine and cotinine were highly variable in both studies. Indirect estimates of plasma clearance (baseline plasma concentration divided by cigarettes per day) together with other factors could account for 18 to 33% of the variability during transdermal nicotine treatment in the smoking cessation study. In contrast, 75 to 99% was accounted for by direct measurements of plasma clearances and systemic dose of nicotine in the pharmacokinetic study. Conclusion: Plasma concentrations of nicotine and cotinine during transdermal nicotine treatment are poorly predicted by clinical history or baseline plasma concentrations. This is a result of inadequate characterisation of highly variable individual pharmacokinetic parameters and absorbed dose of nicotine. Considering the interindividual variability of plasma nicotine and cotinine concentrations together with the lack of clinical end-points for transdermal nicotine dosing, it seems logical to investigate the utility of a therapeutic drug monitoring approach for transdermal nicotine treatment – particularly for high dose regimens (〉 22 mg per 24 hours).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 37 (1989), S. 533-536 
    ISSN: 1432-1041
    Keywords: bismuth ; absorption ; elimination ; pharmacokinetics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The pharmacokinetics of bismuth subcitrate were studied in plasma and urine under conditions of single and multiple dosing (28–56 days) using atomic absorption technique. Single dose plasma pharmacokinetics showed peak concentrations of 5.5–57.5 µg·l−1 (mean=24.7 µg·l−1), reached between 30 and 60 min post dosing with an apparent biphasic elimination pattern. Multiple dose studies showed a continuing rise in plasma concentration and urine excretion rate reaching apparent steady-state levels over 7–29 days (mean=18 days). Washout studies in 6 individuals reciprocated accumulation. Maximum equilibrated plasma levels of 7.6–58.3 µg·l−1 (mean=38.3 µg·l−1) were well below those associated with encephalopathy. The half-life of bismuth elimination was 20.7 days. Present patterns of intermittent dosing with bismuth are unlikely to be associated with bismuth accumulation despite slow accumulation and elimination.
    Type of Medium: Electronic Resource
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