| 1. |
- Desbans, Coraline, et al.
(författare)
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Accurate prediction of variability in CLint and Fm via 3A4 is only obtained by assessing a series of individual cryopreserved human hepatocyte batches
- 2010
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Ingår i: Drug metabolism reviews (Softcover ed.). - New York : Informa Healthcare. - 0360-2532 .- 1097-9883. ; 42:Suppl. 1, s. 274-274
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Tidskriftsartikel (refereegranskat)abstract
- Multiple in-vitro and in-vivo methods are currently assessed and under discussion to predict human clearance and pharmacokinetics from preclinical studies. A combination of high fm with a high fraction metabolism via a single pathway, e.g. via CYP3A4 (fmCYP3A4), has been recognized as a high risk factor for Drug Drug Interactions (DDI) in the clinical setting[1],[2],[3],[4] . Thus, an early predictive tool to allow for appropriate modeling of this potential risk for DDI is highly warranted. Hepatocytes, capable of both phase I and phase II reactions, are an attractive system to study fraction metabolized (fm) via a single pathway. In the present study, intrinsic clearance (CLint) was determined in cryopreserved human hepatocytes in suspension for a set of five compounds with known and variable fm via CYP3A4 (amitriptyline, loratadine, methylprednisolone, midazolam, and tacrolimus) in the absence or presence of ketoconazole. In order to get an insight into the influence of inter-individual variability, twelve batches of cryopreserved human hepatocytes with either high, moderate or low CYP3A4-dependent activity towards midazolam (MDZ) were chosen. Clint values were determined as substrate depletion under shaking conditions (900rpm) using an elliptic shaker as previously reported[5]. For all compounds, the mean CLint for individual donors in absence of ketoconazole correlated very well with literature data on the mean of individual donors1,2,3, and/or pools of donors5. Average fmCYP3A4 for midazolam was 83%, tacrolimus 64%, methylprednisolone 55%, amitriptyline 28%, and loratadine 19% are also well within the literature data2,3,4. Interestingly, the results obtained for a homogenous subpopulation regarding MDZ CLint and percent inhibition by ketoconazole, were not directly related to the ketoconazole sensitive CLint for the other CYP3A4 substrates tested. The variability in CYP3A4 contribution for compounds having multiple metabolic pathways cannot be predicted by the fm3A4 for MDZ. This suggests that an overall prediction of CLint or fm via CYP3A4 for compounds partially metabolized by this enzyme is not possible. Thus, the individual differences in CLint for a given compound and fmCYPi can only be well covered by assessing a series of individual cryopreserved human hepatocyte batches.[1] Lu, C., Miwa, G. T., Prakash, S. R., Gan, L-S. and Balani, S. K. (2007), Drug Metabolism And Disposition, 35: 1, 79–85[2] Lu, C., Hatsis,P., Berg,C., Lee, F. W. and Balani, S. K. (2008), Drug Metabolism And Disposition, 36: 7, 1255–1260[3] Lu, C., Hatsis,P., Berg,C., Lee, F. W. and Balani, S. K. (2008), Drug Metabolism And Disposition, 36: 7, 1261–1266[4] Emoto, C., Murase, S. and Iwasaki, K.(2006), Xenobiotica, 36: 8, 671 — 683[5] Simon ,S., Blanchard, N., Alexandre, E., Hewitt, N. J., Bachellier, P., Heyd, B., Coassolo, P., Schuler, F., Richert, L., (2009) ‘MV-HUF Copenhagen’
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| 2. |
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| 3. |
- Hayeshi, Rose, et al.
(författare)
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Comparison of drug transporter gene expression and functionality in Caco-2 cells from 10 different laboratories
- 2008
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 35:5, s. 383-396
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Tidskriftsartikel (refereegranskat)abstract
- Caco-2 cells, widely used to study carrier mediated uptake and efflux mechanisms, are known to have different properties when cultured under different conditions. In this study, Caco-2 cells from 10 different laboratories were compared in terms of mRNA expression levels of 72 drug and nutrient transporters, and 17 other target genes, including drug metabolising enzymes, using real-time PCR. The rank order of the top five expressed genes was: HPT1>GLUT3>GLUT5>GST1A>OATP-B. Rank correlation showed that for most of the samples, the gene ranking was not significantly different. Functionality of transporters and the permeability of passive transport markers metoprolol (transcellular) and atenolol (paracellular) were also compared. MDR1 and PepT1 function was investigated using talinolol and Gly-Sar transport, respectively. Sulfobromophthalein (BSP) was used as a marker for MRP2 and OATP-B functionality. Atenolol permeability was more variable across laboratories than metoprolol permeability. Talinolol efflux was observed by all the laboratories, whereas only five laboratories observed significant apical uptake of Gly-Sar. Three laboratories observed significant efflux of BSP. MDR1 expression significantly correlated to the efflux ratio and net active efflux of talinolol. PepT1 mRNA levels showed significant correlation to the uptake ratio and net active uptake of Gly-Sar. MRP2 and OATP-B showed no correlation to BSP transport parameters. Heterogeneity in transporter activity may thus be due to differences in transporter expression as shown for PepT1 and MDR1 which in turn is determined by the culture conditions. Absolute expression of genes was variable indicating that small differences in culture conditions have a significant impact on gene expression, although the overall expression patterns were similar.
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| 4. |
- Hilgendorf, Constanze, et al.
(författare)
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Expression of thirty-six drug transporter genes in human intestine, liver, kidney, and organotypic cell lines
- 2007
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 35:8, s. 1333-1340
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Tidskriftsartikel (refereegranskat)abstract
- This study was designed to quantitatively assess the mRNA expression of 36 important drug transporters in human jejunum, colon, liver, and kidney. Expression of these transporters in human organs was compared with expression in commonly used cell lines (Caco-2, HepG2, and Caki-1) originating from these organs to assess their value as in vitro transporter system models, and was also compared with data obtained from the literature on expression in rat tissues to assess species differences. Transporters that were highly expressed in the intestine included HPT1, PEPT1, BCRP, MRP2, and MDR1, whereas, in the liver, OCT1, MRP2, OATP-C, NTCP and BSEP were the main transporters. In the kidney, OAT1 was expressed at the highest levels, followed by OAT3, OAT4, MCT5, MDR1, MRP2, OCT2, and OCTN2. The best agreement between human tissue and the representative cell line was observed for human jejunum and Caco-2 cells. Expression in liver and kidney ortholog cell lines was not correlated with that in the associated tissue. Comparisons with rat transporter gene expression revealed significant species differences. Our results allowed a comprehensive quantitative comparison of drug transporter expression in human intestine, liver, and kidney. We suggest that it would be beneficial for predictive pharmacokinetic research to focus on the most highly expressed transporters. We hope that our comparison of rat and human tissue will help to explain the observed species differences in in vivo models, increase understanding of the impact of active transport processes on pharmacokinetics and distribution, and improve the quality of predictions from animal studies to humans.
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| 5. |
- Linnankoski, Johanna, et al.
(författare)
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Paracellular porosity and pore size of the human intestinal epithelium in tissue and cell culture models
- 2010
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 99:4, s. 2166-2175
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Tidskriftsartikel (refereegranskat)abstract
- The paracellular space defines the passive permeation of hydrophilic compounds in epithelia. The goal of this study was to characterise the paracellular permeation pathway in the human intestinal wall and differentiated epithelial cell models (MDCKII, Caco-2 and 2/4/A1). The permeabilities of hydrophilic polyethylene glycols (PEG) were investigated in diffusion chambers, and mass spectrometry was used to obtain accurate concentrations for each PEG molecule. The paracellular porosity and the size of the pores in the membranes were estimated from the PEG permeability data using an effusion-based approach. The porosities were found to be low (fraction 10−7–10−5 of the epithelial surface) in all investigated membranes. Two different pore sizes (radii 5–6 and >10 Å) were detected in the human intestinal epithelium and the Caco-2 and MDCKII cells, while only one (about 15 Å) in the 2/4/A1 monolayer. The paracellular porosities of the human small intestine and 2/4/A1 monolayers were larger (>10−7) than that of the MDCKII and Caco-2 cells (<10−7). We report for the first time the quantitative values describing both porosity and pore size of the paracellular space in the human intestine. The cell models deviate from the small intestine either with respect to porosity (Caco-2, MDCKII) or pore size distribution (2/4/A1).
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| 6. |
- Neuhoff, Sibylle, et al.
(författare)
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Advantages and disadvantages of using bovine serum albumin and/or Cremophor EL as extracellular additives during transport studies of lipophilic compounds across Caco-2 monolayers
- 2007
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Ingår i: Journal of drug delivery science and technology. - 1773-2247. ; 17:4, s. 259-266
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Tidskriftsartikel (refereegranskat)abstract
- The effects of Cremophor EL (CEL) and bovine serum albumin (BSA) on the active and passive permeation of BCS class II compounds (felodipine, asimadoline) were studied across Caco-2 cells. The effect of BSA on either or both sides of the monolayers, apically applied CEL in the presence ofbasolateral BSA and the effect ofaddition of CEL on P-gp by the use ofquinidine were investigated. Presence of 4% BSA improved sink conditions and recovery from 60 to 95% for both felodipine and asimadoline. Efflux ratios obtained under comparable sink conditions, indicated that felodipine was transported by passive diffusion, while quinidine and asimadoline were transported actively. CEL decreased the transport rate for felodipine and asimadoline in the absorptive direction and increased in the secretory direction at different CEL concentrations, most likely due to the incorporation of drug into micelles. Our results indicate that inclusion of BSA is generally sufficient to increase the recovery for lipophilic BCS class II compounds. The overall effect of CEL on the permeability of a drug is compound specific and, therefore, less predictable and cannot be recommended.
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| 7. |
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| 8. |
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| 9. |
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| 10. |
- Neuhoff, Sibylle, et al.
(författare)
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pH-Dependent passive and active transport of acidic drugs across Caco-2 cell monolayers
- 2005
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Ingår i: European Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0928-0987 .- 1879-0720. ; 25:2-3, s. 211-220
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate pH-dependent passive and active transport of acidic drugs across Caco-2 cells. Therefore, the bidirectional pH-dependent transport of two acidic drugs, indomethacin and salicylic acid, across Caco-2 cells was studied in the physiological pH range of the gastrointestinal tract. The transport of both drugs decreased with increased pH, as expected from the pH-partition hypothesis. Net absorption occurred when the basolateral pH exceeded the apical pH. Concentration dependence and transporter inhibition studies indicated passive transport for indomethacin and a mixture of pH-dependent passive and active influx for salicylic acid. Unexpectedly, active and passive drug transport results were indistinguishable in temperature dependency studies. The transport of salicylic acid (apical pH 5.0; basolateral pH 7.4) was partly blocked by inhibitors of the proton-dependent transporters MCT1 (SLC16A1) and OATP-B (SLC21A9, SLCO2B1). This study shows that the asymmetry in bidirectional transport of acidic drugs is affected by both passive and active components in the presence of pH gradients across Caco-2 cells. Thus, combined studies of concentration-dependency and transport-inhibition are preferred when acidic drug transport is studied in a pH gradient. The findings of this in vitro study can be extrapolated to in vivo situations involving an acidic microclimate.
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