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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 55 (2000), S. 821-825 
    ISSN: 1432-1041
    Keywords: Key words Phenobarbitone ; CYP2C19 ; Genetic polymorphism ; Pharmacokinetics ; NONMEM
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objective: The aim of this study was to clarify the effect of genetic polymorphisms of CYP2C19 on the pharmacokinetics of phenobarbitone (PB) using a nonlinear mixed-effects model (NONMEM) analysis in Japanese adults with epilepsy. Methods: A total of 144 serum PB concentrations were obtained from 74 subjects treated with both PB and phenytoin but without valproic acid. All patients were classified into three groups by CYP2C19 genotyping: G1, G2 and G3 were homozygous for the wild type of CYP2C19 (*1/*1), heterozygous extensive metabolizers (EMs), (*1/*2 or *1/*3), and poor metabolizers (PMs), (*2/*2, *2/*3), respectively. All data were analyzed using NONMEM to estimate pharmacokinetic parameters of PB with respect to the CYP2C19 genotype. Results: Thirty-three patients belonged to G1 (44.6%), 35 to G2 (47.3%), and 6 to G3 (8.1%). The total clearance (CL) of PB significantly decreased by 18.8% in PMs (G3) relative to EMs (G1 and G2). The CL tended to be lower in G2 than in G1. Conclusion: In this study, we first demonstrated the effect of the CYP2C19 polymorphism on pharmacokinetics of PB by genotyping. The contribution of other metabolic enzymes in the metabolism of PB in humans remains to be elucidated; however, it appears that the disposition of PB is mediated in part by this enzyme. The estimated population clearance values in the three genotype groups can be used to predict the PB dose required to achieve an appropriate serum concentration in an individual patient.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1041
    Keywords: Key words CYP2C9 ; Genetic polymorphism ; Diclofenac
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract Objectives: Evidence exists to suggest that diclofenac is metabolised by CYP2C9. The present study was undertaken in order to evaluate the effect of the single CYP2C9*3 variant on drug metabolism using diclofenac as a probe drug. Methods: A single dose of diclofenac was administered orally to 12 healthy subjects in whom the genotype of CYP2C9 had been determined previously. The disposition kinetics of diclofenac were compared between homozygotes for the wild type (CYP2C9*1/*1, n=6) and heterozygotes for the Leu359 variant (CYP2C9*1/*3, n=6). Results: For diclofenac, the following kinetic parameters were observed in the CYP2C9*1/*1 and CYP2C9*1/*3 subjects, respectively (mean ± SD): apparent oral clearance (ml/kg/h) 355.8 ± 56.9 and 484.4 ± 155.3; area under plasma concentration–time curve (μg h/ml) 2.7 ± 0.7 and 1.9 ± 0.6. The formation clearance of 4′-hydroxydiclofenac (ml/kg/h) was 63.6 ± 19.1 in the CYP2C9*1/*1 subjects compared with 75.9 ± 27.6 in the CYP2C9*1/*3 subjects. There were no significant differences in any of the kinetic parameters for either diclofenac disposition or formation clearance of 4′-hydroxydiclofenac between the two genotype groups. Conclusion: Since the disposition kinetics of diclofenac does not change in subjects with the single CYP2C9*3 mutant allele, it is suggested that the effects of CYP2C9 polymorphisms on the drug metabolism tend to be substrate specific.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 5 (1978), S. 220-223 
    ISSN: 0306-042X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A highly sensitive and specific method for the determination of nifedipine in plasma is described. Nifedipine was oxidized to its pyridine analogue with nitrous acid and determined by selected ion monitoring. Deuterium labeled nifedipine was used as an internal standard. Plasma levels as low as 5 ng ml-1 were measured. The usefulness of the method was demonstrated by obtaining plasma concentration curves for humans after an oral dose of 10 mg.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The pharmacokinetics of 2-(N-benzyl-N-methylamino)ethyl methyl 2, 6-dimethyl 4-(m-nitrophenyl)-1, 4-dihydropyridine-3, 5-dicarboxylate hydrochloride (nicardipine hydrochloride) was studied in dogs by using two deuterium labelled compounds (N-[2H3]methyl and N-[2H7]benzyl derivatives). The biological isotope effect of the [2H7]derivative, which was calculated from the half-lives in vivo and the metabolic rates in vitro, was 1.37 and 1.36, respectively, suggesting that debenzylation in the liver was one of the rate limiting steps of elimination of the drug, while the [2H3] derivative did not show this effect. The [2H3] derivative was administered orally or intravenously to dogs 2 h after oral administration of the non-labelled compound, and the plasma concentration of the [2H3] derivative was determined by the selected ion monitoring method. The biological half-lives, AUC and systemic availability increased with increasing doses of non-labelled nicardipine hydrochloride, while plasma clearance decreased, suggesting that the hepatic enzyme activity metabolizing the drug was partly saturated by the drug or its metabolites.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 18 (1987), S. 153-155 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman optical activity (ROA) spectra of some azo dyes binding to cyclodextrins have been measured. This appears to be the first successful attempt to measure the ROA induced in achiral molecules by intermolecular interaction with chiral molecules. There was no relationship between the ROA signals and the Raman shifts accompanying inclusion phenomenon. From comparison of the ROA spectra of methyl orange with α-cyclodextrin and congo red with γ-cyclodextrin, it seems that the ROA spectra reflect the difference in the positions of the SO3- groups in the guest molecules.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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