Quantification of mephenytoin and its metabolites 4′‐hydroxymephenytoin and nirvanol in human urine using a simple sample processing method

Klaassen, Tobias; Kasel, Dirk; Harlfinger, Stephanie; Fuhr, Uwe

doi:10.1002/rcm.1539

Cited by 9 publications

(6 citation statements)

References 16 publications

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“…The method for the quantification of 4Ј-hydroxymephenytoin with 4Ј-methoxymephenytoin as internal standard in urine by LC-MS/MS has been published in detail (Klaassen et al, 2004). Linearity of the weighted (1/concentration) calibration curves over a concentration range from 15 to 10,000 ng/ml was expressed in correlation coefficients Ͼ0.999.…”

Section: Methodsmentioning

confidence: 99%

Effect of propiverine on cytochrome P450 enzymes: a cocktail interaction study in healthy volunteers

Tomalik-Scharte

Jetter²,

Kinzig‐Schippers³

et al. 2005

Drug Metabolism and Disposition

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ABSTRACT:The present study was conducted to assess a possible in vivo effect of propiverine, an anticholinergic drug to treat urinary incontinence and related disorders, on the activity of intestinal CYP3A4 and of hepatic CYP3A4, CYP2C9, CYP2C19, and CYP1A2. The activity of the respective cytochromes P450 was measured using the following metrics of selective substrates given as a tailored low-dose phenotyping cocktail: intestinal availability of midazolam Propiverine hydrochloride, described below as propiverine, is indicated for the treatment of urinary incontinence, as well as urinary urgency and frequency in patients who have either idiopathic detrusor overactivity (overactive bladder) or neurogenic detrusor overactivity (detrusor hyperreflexia) from spinal cord injuries, e.g., transverse lesion paraplegia. It exhibits antagonistic effects toward muscarinic acetylcholine receptors and calcium channel-modulating properties (Siegmund et al., 1990;Yono et al., 1999;Madersbacher and Mürtz, 2001).After oral administration, propiverine is rapidly and almost completely absorbed from the gastrointestinal tract. The maximal serum concentration is reached approximately 90 min after a single dose of 15 mg. Propiverine undergoes extensive presystemic metabolism via N-oxidation to propiverine-N-oxide with involvement of cytochrome P450 enzymes. Mean elimination half-life after chronic administration of propiverine is about 15 h. The major fraction of propiverine and its metabolites is eliminated in the urine (Haustein and Hüller, 1988;Siepmann et al., 1998). Information on the enzymes mediating phase I metabolism of propiverine has been obtained in several in vitro systems (APOGEPHA, data on file). The primary metabolic route involves the oxidation of the piperidyl-N and is mediated by CYP3A4 and flavin-containing monoxygenases 1 and 3, and leads to the formation of the much less active N-oxide. CYP2C9 and CYP2C19 may also mediate a fraction of overall propiverine elimination, whereas other enzymes (e.g., CYP1A2 and CYP2D6) were involved to a minor extent.Several studies concerning possible drug-drug interactions of propiverine have been published. Müller et al. (1993) demonstrated that there is no effect of the CYP2D6 genotype on propiverine biotransformation in humans, so that no effect of CYP2D6 inhibitors on propiverine pharmacokinetics is expected. Results of a study performed in rats provided no evidence for propiverine to cause relevant drug-drug interactions (Borchert et al., 1986). Studies on the effect of propiverine on drug-metabolizing enzymes in human and rat hepatocyte cultures demonstrated an increase in CYP3A4 mRNA and This study was supported by APOGEPHA Arzneimittel GmbH, Dresden, Germany.Article, publication date, and citation information can be found at

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Section: Methodsmentioning

confidence: 99%

Effect of propiverine on cytochrome P450 enzymes: a cocktail interaction study in healthy volunteers

Tomalik-Scharte

Jetter²,

Kinzig‐Schippers³

et al. 2005

Drug Metabolism and Disposition

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“…Owing to its idiosyncratic side effects, mephenytoin is currently of limited use therapeutically. Nevertheless its enantioselective metabolism has fostered a unique niche in the pharmacogenetics area, particularly as a phenotypic probe of human CYP2C19 (Klaassen et al, 2004). Indeed, in humans, mephenytoin undergoes p-hydroxylation to form 4′-hydroxymephenytoin by CYP2C19, or N-demethylation to form the active nirvanol mainly by CYP2B6 with partial contribution of CYP2C9 (Jansson et al, 2006).…”

Section: Hydantoinsmentioning

confidence: 99%

Chiral chromatographic resolution of antiepileptic drugs and their metabolites: a challenge from the optimization to the application

Fortuna

Alves

2013

Biomedical Chromatography

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A large number of the antiepileptic drugs (AEDs) presently available for clinical practice are chiral compounds while others, although achiral, may originate pharmacologically active chiral metabolites in vivo. The well-known implications of chirality in pharmacokinetics and pharmacodynamics demand the investigation of pharmacological properties for a racemic mixture and each enantiomer. To achieve these objectives, appropriate chiral analytical methods must be available. This article provides the first review of the current state of the art in chiral chromatographic methods available for quantifying enantiomers of AEDs in distinct matrices. Particular attention is paid to the methodological aspects and optimization strategies that successfully allow enantiomeric chromatographic separation of chiral AEDs and/or metabolites. Furthermore, the relevance of these methods in supporting the discovery and development of chiral AEDs is emphasized. In parallel and whenever available, the principal validation parameters are herein considered and related to the stage of drug discovery and development. In an attempt to optimize anticonvulsant activity and simultaneously diminish toxic effects, many pharmaceutical companies have started to manufacture single enantiomers. Therefore, chiral chromatographic techniques will be essential and the information herein compiled can be used as a framework for developing them.

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“…29 Both the fraction of free, unconjugated 4´-hydroxymephenytoin and total 4´-hydroxymephenytoin after β−glucuronidase pre-treatment 29 were measured in samples of study A and B. For study C and D only total 4´-hydroxymephenytoin concentrations up to 12 hours postdose were determined, while nirvanol concentrations were determined for all collection periods of study A, B and C.…”

Section: Urine Analysis By Lc-ms/msmentioning

confidence: 99%

Assessment of urinary mephenytoin metrics to phenotype for CYP2C19 and CYP2B6 activity

Klaassen

Jetter²,

Tomalik-Scharte³

et al. 2007

Eur J Clin Pharmacol

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OBJECTIVES: (S)-Mephenytoin is selectively metabolised to (S)-4'-hydroxymephenytoin by CYP2C19. The urinary excretion of 4'-hydroxymephenytoin reflects the activity of individual enzymes. We evaluated fractioned urinary collection and beta-glucuronidase pre-treatment in order to determine the optimal CYP2C19 metrics. We also assessed whether urinary excretion of N-desmethylmephenytoin (nirvanol) might be a useful CYP2B6 metric in in vivo studies. METHODS: A 50-mg dose of mephenytoin was administered to 52 volunteers as a component of phenotyping cocktails in four separate studies. Urine was collected up to 166 h post-dose. Urinary excretion of 4'-hydroxymephenytoin and nirvanol was quantified by liquid chromatography-tandem mass spectrometry, and common CYP2C19 and CYP2B6 genotypes were determined. RESULTS: Cumulative excretion of 4'-hydroxymephenytoin in urine with beta-glucuronidase treatment collected from before mephenytoin administration up to 12-16 h thereafter showed the greatest difference between CYP2C19 genotypes and the lowest intra-individual variability (7%). Renal elimination of nirvanol was highest for a *4/*4 individual and lowest for individuals carrying the *5/*5 and *1/*7 genotype, but lasted for several weeks, thus making its use in cross-over studies difficult. CONCLUSION: Cumulative urinary excretion of 4'-hydroxymephenytoin 0-12 h post-administration is a sensitive and reproducible metric of CYP2C19 activity, enabling the effect of a drug on CYP2C19 to be assessed in a small sample size of n=6 volunteers. While nirvanol excretion may reflect CYP2B6 activity in vivo, it is not useful for CYP2B6 phenotyping. We evaluated fractioned urinary collection and β-glucuronidase pre-treatment to assess the optimal CYP2C19 metric. Furthermore, we addressed whether urinary excretion of N-desmethylmephenytoin (nirvanol) might be a useful CYP2B6 metric in vivo.Methods: 50 mg of mephenytoin was administered to 52 volunteers as part of phenotyping cocktails in four separate studies. Urine was collected up to 166 hours postdose. Urinary excretion of 4'-hydroxymephenytoin and nirvanol was quantified by LC-MS/MS, and common CYP2C19 and CYP2B6 genotypes were determined.Results: Cumulative excretion of 4'-hydroxymephenytoin in urine with β-glucuronidase treatment collected from before mephenytoin administration up to 12-16 hours thereafter showed the greatest difference between CYP2C19 genotypes and the lowest intraindividual variability (7 %). Renal elimination of nirvanol was highest for a *4/*4 individual and lowest for individuals carrying the *5/*5 and *1/*7 genotype, but lasted for several weeks, thus making its use in cross-over studies difficult. Conclusion:Cumulative urinary excretion of 4'-hydroxymephenytoin 0-12 hours is a sensitive and reproducible metric of CYP2C19 activity, allowing a small sample size of n=6 volunteers to assess the effect of a drug on CYP2C19. While nirvanol excretion may reflect CYP2B6 activity in vivo, it is not useful for CYP2B6 phenotyping.3

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Quantification of mephenytoin and its metabolites 4′‐hydroxymephenytoin and nirvanol in human urine using a simple sample processing method

Cited by 9 publications

References 16 publications

Effect of propiverine on cytochrome P450 enzymes: a cocktail interaction study in healthy volunteers

Effect of propiverine on cytochrome P450 enzymes: a cocktail interaction study in healthy volunteers

Chiral chromatographic resolution of antiepileptic drugs and their metabolites: a challenge from the optimization to the application

Assessment of urinary mephenytoin metrics to phenotype for CYP2C19 and CYP2B6 activity

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