Are you Yin Hu?

Claim your profile

Publications (3)7.95 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract 1. Human hepatocytes that had been cold-preserved in SureTran(TM) matrix (Abcellute Ltd, Cardiff, UK) were used for studies on cell viability, cytochrome P450 (CYP) 3A4, 2B6 and 1A2 induction and hepatic drug transporters. It has recently been shown that basal CYP activities are maintained in cold-preserved hepatocytes (Palmgren et al., 2012). 2. After 5 d of cold preservation, the viability was still more than 70%, and after 8 d it was around 60%. In hepatocytes that had been cold-preserved for 3 d, the activity of CYP3A4 was induced around 15-fold upon treatment with 8 µM rifampicin for 72 h. For CYP2B6, the activity was induced 4- to 16-fold in hepatocytes that had been cold-preserved for 3 d and thereafter treated with 1 mM phenobarbital for 72 h. The activity of CYP1A2 was low and close to the limit of detection in non-treated cells that had been cold-preserved for up to 3 d, while the activity increased in cells treated with 0.3-25 µM β-naphthoflavone for 72 h. CYP3A4, 2B6 and 1A2 mRNA levels were only determined with hepatocytes from one donor and increased upon treatment with the inducers. 3. Hepatic uptakes of estrone-3-sulfate, taurocholate, ipratropium and rosuvastatin were stable in human hepatocytes that had been cold-preserved for up to 2 d. 4. In summary, cold-preserved human hepatocytes demonstrate retained viability and can advantageously be used for in vitro induction studies and for studies of hepatic uptake transporters.
    Xenobiotica 04/2013; · 2.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Abstract 1. Intestinal loss, 1 - (F(obs)/f(H)), is the missing fraction of the dose that is unexplained by systemic clearance. Here, we investigated whether intestinal loss in rat is predictive for human, and whether intestinal metabolism explained observed differences between rat and human. 2. For 81 marketed drugs, human and rat intestinal loss values were calculated from the literature and in-house sources. To examine the contribution of intestinal cytochrome P450-mediated metabolism to the high observed intestinal loss in the rat, metabolism was determined in rat and human intestinal microsomes for 15 compounds. 3. Oral bioavailability poorly correlated between rat and human. Twenty-two compounds in the human and 47 compounds in the rat showed an intestinal loss of more than 20%. The intestinal availability for many compounds was higher in human than in rat. Selected compounds, however, were more stable in rat than in human intestinal microsomes. 4. The rat poorly predicts the risk for intestinal loss in human; many compounds in rat had lower bioavailability than anticipated based on the hepatic clearance, but demonstrated little intestinal loss in human. This discrepancy appeared not to be caused by a higher cytochrome P450-mediated intestinal metabolism in the rat.
    Xenobiotica 01/2013; · 2.10 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Time dependent inhibition (TDI) of cytochrome P450 (CYP) is usually studied in human liver microsomes (HLM), by investigating whether the inhibitory potency is increased with increased incubation times. The presented work was initiated due to a discrepancy observed for the CYP3A4 TDI results for a drug candidate compound (AZD3839) from an early screening method, where no TDI was detected compared to a regulatory method, where TDI was detected. We show here that the different solvents present in the respective studies; DMSO (screening method) versus methanol or water (regulatory method), were the reason to the different TDI results. We further demonstrate why DMSO, present at the levels of 0.2% and 0.5% in the incubations, masked the TDI effect. In addition to the TDI experiments performed in HLM, TDI studies with AZD3839 were performed in pooled human hepatocytes (Hhep) from different suppliers, using DMSO, methanol or water. The results from these experiments show no TDI or attenuated TDI effect depending on the supplier. Metabolite identification of the compound dissolved in DMSO, methanol or water, after incubations with the different systems (HLM or Hhep) show different profiles, which may be the reason to the differences in the TDI outcomes. Thorough investigations of the biotransformation of AZD3839 have been performed, in order to find the reactive pathway causing the TDI of CYP3A4, and are presented here. Our findings show that the in vitro risk profile for DDI potential of AZD3839 is very much dependent on the chosen test system and the experimental conditions used.
    Drug metabolism and disposition: the biological fate of chemicals 10/2012; · 3.74 Impact Factor