High amounts of acrylamide in some foods result in an estimated daily mean intake of 50 Mg for a western style diet. Animal studies have shown the carcinogenicity of acrylamide upon oral exposure. However, only sparse human toxicokinetic data is available for acrylamide, which is needed for the extrapolation of human cancer risk from animal data. We evaluated the toxicokinetics of acrylamide in six young healthy volunteers after the consumption of a meal containing 0.94 mg of acrylamide. Urine was collected up to 72 hours thereafter. Unchanged acrylamide, its mercapturic acid metabolite N-acetyl-S-(2-carbamoylethyl)-cysteine (AAMA), its epoxy derivative glycidamide, and the respective metabolite of glycidamide, N-acetyl-S-(2-hydroxy-2-carbamoylethyl)cysteine (GAMA), were quantified in the urine by liquid chromatography-mass spectrometry. Toxicokinetic variables were obtained by noncompartmental methods. Overall, 60.3 F 11.2% of the dose was recovered in the urine. Although no glycidamide was found, unchanged acrylamide, AAMA, and GAMA accounted for urinary excretion of (mean F SD) 4.4 F 1.5%, 50.0 F 9.4%, and 5.9 F 1.2% of the dose, respectively. Apparent terminal elimination half-lives for the substances were 2.4 F 0.4, 17.4 F 3.9, and 25.1 F 6.4 hours. The ratio of GAMA/AAMA amounts excreted was 0.12 F 0.02. In conclusion, most of the acrylamide ingested with food is absorbed in humans. Conjugation with glutathione exceeds the formation of the reactive metabolite glycidamide. The data suggests an at least 2-fold and 4-fold lower relative internal exposure for glycidamide from dietary acrylamide in humans compared with rats or mice, respectively. This should be considered for quantitative cancer risk assessment. (Cancer Epidemiol Biomarkers Prev 2006;15(2):266 -71)

The pharmacokinetics of dextromethorphan (DM) is markedly influenced by cytochrome P450 2D6 (CYP2D6) enzyme polymorphisms. The aim of this study was to quantify the effects of the CYP2D6*1, *2, and *41 variants on DM metabolism in vivo and to identify other sources of pharmacokinetic variability. Concentrations of DM and dextrorphan (DO) in plasma and urine were evaluated in 36 healthy Caucasian men. These volunteers participated in three clinical studies and received a single oral dose of 30 mg DM-HBr. Data were modeled simultaneously using the population pharmacokinetics NONMEM software. A five-compartment model adequately described the data. The activity levels of the alleles assessed differed significantly. The clearance attributable to an individual CYP2D6*1 copy was 2.5-fold higher as compared with CYP2D6*2 (5,010 vs. 2,020 l/h), whereas the metabolic activity of CYP2D6*41 was very low (85 l/h). Urinary pH was confirmed as a significant covariate for DM renal clearance. These results refine genotype-based predictions of pharmacokinetics for DM and presumably for other CYP2D6 substrates as well. were modelled simultaneously using the population pharmacokinetic NONMEM software. A five-compartment model adequately described the data. Activities of the alleles assessed differed significantly. The clearance attributable to an individual CYP2D6*1 copy was 2.5-fold higher compared to CYP2D6*2 (5010 vs 2020 L/h) while the metabolic activity for CYP2D6*41 was very low (85 L/h). Urinary pH was confirmed as a significant covariate for dextromethorphan renal clearance. These results refine genotype-based prediction of pharmacokinetics for dextromethorphan and presumably other CYP2D6 substrates.3

(2008). Effect of an antiretroviral regimen containing ritonavir boosted lopinavir on intestinal and hepatic CYP3A, CYP2D6 and P-glycoprotein in HIV-infected patients. Clinical Pharmacology and Therapeutics, 84 (1) This study aimed to quantify the inhibition of CYP3A, CYP2D6 and P-glycoprotein in HIVinfected patients receiving an antiretroviral therapy containing ritonavir boosted lopinavir, and to identify factors influencing ritonavir and lopinavir pharmacokinetics.We measured activities of CYP3A, CYP2D6 and P-glycoprotein in 28 patients before and during antiretroviral therapy using a cocktail phenotyping approach. Activities, demographics, and genetic polymorphisms in CYP3A, CYP2D6, and P-glycoprotein were tested as covariates.

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