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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 42 (1992), S. 587-591 
    ISSN: 1432-1041
    Schlagwort(e): Codeine ; Quinidine ; CYP2D6 ; hypolagesia ; drug interaction
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary We have studied the hypoalgesic effect of codeine (100 mg) after blocking the hepatic O-demethylation of codeine to morphine via the sparteine oxygenase (CYP2D6) by quinidine (200 mg). The study was performed in 16 extensive metabolizers of sparteine, using a double-blind, randomized, four-way, cross-over design. The treatments given at 3 h intervals during the four sessions were placebo/placebo, quinidine/placebo, placebo/codeine, and quinidine/codeine. We measured pin-prick pain and pain tolerance thresholds to high energy argon laser stimuli before and 1, 2, and 3 h after codeine or placebo. After codeine and placebo, the peak plasma concentration of morphine was 6–62 (median 18) nmol·.l−1. When quinidine pre-treatment was given, no morphine could be detected (〈4 nmol·l−1) after codeine. The pin-prick pain thresholds were significantly increased after placebo/codeine, but not after quinidine/codeine compared with placebo/placebo. Both placebo/codeine and quinidine/codeine increased pain tolerance thresholds significantly. Quinidine/codeine and quinidine/placebo did not differ significantly for either pin-prick or tolerance pain thresholds. These results are compatible with local CYP2D6 mediated formation of morphine in the brain, not being blocked by quinidine. Alternatively, a hypoalgesic effect of quinidine might have confounded the results.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 30 (1986), S. 43-49 
    ISSN: 1432-1041
    Schlagwort(e): imipramine ; desipramine ; hydroxymetabolites ; plasma concentration monitoring ; dose-dependent kinetics ; drug interaction ; levomeprazine ; perphenazine ; therapeutic response ; sparteine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary Seventeen hospitalized patients (age 39–66 years), received a loading dose of 100 mg imipramine HCl and then 50 mg b.i.d. The 12-h plasma concentration at steady-state varied between 40–637 nmol/l for imipramine, 49–1148 nmol/l for desipramine and 89–1603 nmol/l for imipramine + desipramine. Guided by plasma level monitoring, a final therapeutic plasma level between 548–910 nmol/l for imipramine + desipramine was achieved (therapeutic dose range: 50–400 mg/day). Mean time to reach the therapeutic level was 19 days. The mean 2-OH-imipramine/imipramine ratio was 0.24 and mean 2-OH-desipramine/desipramine ratio was 0.56. There was a significant intrapatient correlation between the two ratios, both during 100 mg imipramine/d and at the therapeutic dose level. A low ratio was associated with high imipramine and particularly with a high desipramine level. Well defined steady state levels were established at two different dose levels in 12 patients and at three dose levels in 5 patients. With increasing dose there was a marked and disproportionate rise in the desipramine level and to some extent in the imipramine level. Saturation of imipramine and desipramine hydroxylation appeared to be responsible for the dose-dependent kinetics. Concomitant treatment with levomepromazine and perphenazine in one patient resulted in a significant rise both in imipramine and desipramine concentration, apparently due to inhibition of the hydroxylation. Eleven out of twelve endogenously depressed patients responded completely to treatment, whereas the response was poor in the non-endogenously depressed patients despite optimal drug levels.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 37 (1989), S. 155-160 
    ISSN: 1432-1041
    Schlagwort(e): imipramine ; desipramine ; quinidine ; sparteine oxidation ; cytochrome P450 isoforms ; genetic polymorphism ; drug interaction ; metabolic clearance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary On separate occasions 6 extensive metabolizers of sparteine took a single oral dose of 100 mg imipramine and desipramine before and during the intake of quinidine sulphate 200 mg/day. During quinidine the total oral clearance of imipramine on average was reduced by 35%, and that of desipramine by 85%. The clearance of imipramine via demethylation was not significantly reduced during quinidine administration, whereas its clearance by other pathways, largely 2-hydroxylation, was reduced by more than 50%. 2-OH-Imipramine and 2-OH-desipramine were detected in plasma before (maximum concentrations 30–100 nmol · l−1) but not during quinidine. It appears that quinidine is a potent inhibitor of the sparteine/debrisoquine oxygenase, P450dbl, which is responsible for the 2-hydroxylation of imipramine and desipramine, but not of the P450 isozyme responsible for the demethylation of imipramine.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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