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  • 1
    Electronic Resource
    Electronic Resource
    P-glycoprotein does not actively transport nicotine and cotinine (2005)
    Oxford, UK : Blackwell Publishing Ltd
    Addiction biology 10 (2005), S. 0 
    Details
    ISSN: 1369-1600
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The ABCB1 gene transporter P-glycoprotein (P-gp) exists in the blood – brain barrier (BBB) and placenta and limits many drugs passing through the BBB and placenta. Several recent studies have raised confounding results regarding the roles of P-gp in nicotine disposition. To ascertain this question, we examined the effects of nicotine and its major oxidative metabolite, cotinine, on ATPase activity using P-gp containing membranes, in which nicotine and cotinine-stimulated inorganic P i was used as a marker of the binding affinity of nicotine and cotinine to P-gp. At concentrations ranging from 5 to 1000 ?μm, both nicotine and cotinine produced modest stimulative effects on ATPase activity in the P-gp containing membrane. The Clint values of nicotine and cotinine were 0.01 and 0.007 minute  − 1  × 10  − 3, respectively. The positive control, verapamil, at concentrations ranging from 1 to 100?μ m, created apparent stimulative effects on ATPase activity, with a Clint value of 1.7 minute  − 1  × 10  − 3, consistent with previously reported results. The results of the current study suggest that nicotine and cotinine were not actively transported by P-gp out of the cells. The observed carrier-mediated nicotine transport in various cell lines may be mediated by other transporter proteins but not P-gp.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1080/13556210500122995
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  • 2
    Electronic Resource
    Electronic Resource
    The analysis and disposition of imipramine and its active metabolites in man (1984)
    Springer
    Psychopharmacology 82 (1984), S. 310-317 
    Details
    ISSN: 1432-2072
    Keywords: Imipramine ; Desipramine ; 2-Hydroxyimipramine ; 2-Hydroxydesipramine ; Active metabolites ; Metabolite disposition ; Pharmacokinetics ; First-pass metabolism ; Transit time ; Availability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Single oral and intramuscular (i.m.) doses of imipramine (IMI) were administered to four normal males. Serum and urine concentrations of IMI, desipramine (DMI) and their unconjugated 2-hydroxy metabolites were measured by high-pressure liquid chromatography (HPLC). Urinary conjugated 2-hydroxy metabolites were also measured after enzyme hydrolysis. Computer analysis of serum concentration and urinary excretion rate data allowed confirmation of drug and metabolite kinetics, and calculation of pharmacokinetic parameters. The rapid appearance of the metabolites in serum indicates that sequential firstpass metabolism of IMI involves both hydroxylation and demethylation. However, the dose-normalized areas under the serum concentration-time curves indicate that the fractions of the doses converted to metabolites were similar after both routes of IMI administration. Similar total fractions of the i.m. and oral doses recovered in urine indicate complete absorption of the oral doses. Inclusion of the metabolites increased the apparent availability of active components after oral IMI from 22%–50% to 45%–94%. Both the 2-hydroxy metabolites exhibited formation rate-limited kinetics, whereas DMI kinetics were elimination rate-limited. The t 1/2 of IMI and 2-hydroxyimipramine (2-OH-IMI) was 6–18 h, while that of DMI and 2-hydroxydesipramine (2-OH-DMI) was 12–36 h. The t 1/2 of these compounds was 1.5–2 times longer after the i.m. doses. The metabolite/parent ratios and the disposition of the individual metabolites confirm findings that chronic dosing results in only limited accumulation of hydroxy metabolites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00427676
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  • 3
    Electronic Resource
    Electronic Resource
    Metabolism and Pharmacokinetics of Selective Serotonin Reuptake Inhibitors (1999)
    Springer
    Cellular and molecular neurobiology 19 (1999), S. 443-466 
    Details
    ISSN: 1573-6830
    Keywords: selective serotonin reuptake inhibitors ; metabolism ; pharmacokinetics ; fluoxetine ; fluvoxamine ; paroxetine ; sertraline ; citalopram ; cytochrome P450
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract 1. Five drugs with the predominant pharmacologic effect of inhibiting the neuronal reuptake of serotonin are available worldwide for clinical use. This class of psychoactive drugs, known as selective serotonin reuptake inhibitors (SSRIs), is comprised of fluoxetine, sertraline, paroxetine, fluvoxamine, and citalopram. 2. The SSRIs appear to share similar pharmacodynamic properties which translate to efficacy in the treatment of depression and anxiety syndromes. The drugs are differentiated by their pharmacokinetic properties with regard to stereochemistry, metabolism, inhibition of cytochrome enzymes, and participation in drug–drug interactions. Studies focusing on the relationship of plasma drug concentration to therapeutic and adverse effects have not confirmed the value of plasma concentration monitoring. 3. This review summarizes the metabolism and relevant pharmacokinetic properties of the SSRIs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006934807375
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    Paper (German National Licenses)
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