ABSTRACT
BACKGROUND/AIMS: Acetaminophen (APAP) effects on intestinal barrier properties are less investigated. APAP may lead to a changed bioavailability of a subsequently administered drug or diet in the body. We investigated the influence of APAP on enterocytic cell membrane properties that are able to modify the net intestinal absorption of administered substances across the Caco-2 barrier model. METHODS: The effect of APAP on cytotoxicity was measured by LDH assay, TER value and cell capacitance label-free using impedance monitoring, membrane permeability by FITC-dextrans, and efflux transporter MDR1 activity by Rh123. APAP levels were determined by HPLC analysis. Cell membrane topography and microvilli were investigated using SEM and intestinal alkaline phosphatase (Alpi) and tight junction protein 1 (TJP1) expression by western blot analysis. RESULTS: APAP changed the apical cell surface, reduced the number of microvilli and protein expression of Alpi as a brush border marker and TJP1, increased the membrane integrity and concurrently decreased cell capacitance over time. In addition, APAP decreased the permeability to small molecules and increased the efflux transporter activity, MDR1. CONCLUSION: APAP alters the Caco-2 cell membrane properties by different mechanisms and reduces the permeability to administered substances. These findings may help to optimize therapeutic implications.
Subject(s)
Acetaminophen/pharmacology , Cell Membrane/drug effects , Epithelial Cells/drug effects , Absorption/drug effects , Alkaline Phosphatase/metabolism , Analgesics, Non-Narcotic/pharmacology , Caco-2 Cells , Cell Membrane Permeability/drug effects , Dose-Response Relationship, Drug , Epithelial Cells/ultrastructure , GPI-Linked Proteins/metabolism , Humans , Microscopy, Electron, Scanning , Mitochondria/drug effectsABSTRACT
Exposure to chemicals absorbed by the skin can threaten human health. In order to standardise the predictive testing of percutaneous absorption for regulatory purposes, the OECD adopted guideline 428, which describes methods for assessing absorption by using human and animal skin. In this study, a protocol based on the OECD principles was developed and prevalidated by using reconstructed human epidermis (RHE). The permeation of the OECD standard compounds, caffeine and testosterone, through commercially available RHE models was compared to that of human epidermis and animal skin. In comparison to human epidermis, the permeation of the chemicals was overestimated when using RHE. The following ranking of the permeation coefficients for testosterone was obtained: SkinEthic > EpiDerm, EPISKIN > human epidermis, bovine udder skin, pig skin. The ranking for caffeine was: SkinEthic, EPISKIN > bovine udder skin, EpiDerm, pig skin, human epidermis. The inter-laboratory and intra-laboratory reproducibility was good. Long and variable lag times, which are a matter of concern when using human and pig skin, did not occur with RHE. Due to the successful transfer of the protocol, it is now in the validation process.
