Question: 

Intestinal absorption is required for a sufficiently high bioavailability of drugs or nutrients administered by the peroral route and could be influenced by N -acetyl-p-aminophenol (APAP), the most widely used pharmaceutical analgesic and antipyretic agent in the world. In this study the effect of APAP on the Caco-2 cell barrier model was analyzed using an impedance-based cell monitoring system.

Methods: 

Caco-2 cells seeded onto inserts were differentiated for 21 days, followed by APAP-administration for 24h. The cell transepithelial electrical resistance (TER) and capacitance C_cl were analyzed using a impedance based cell monitoring system. The membrane integrity was tested by Lucifer Yellow and multidrug resistance gene 1 (MDR1) activity by rhodamine123.

Results: 

Impedance spectroscopy revealed a significant increase of TER value in a dose-dependent manner due to APAP that is correlated with the decrease of Lucifer Yellow permeability. Furthermore, APAP decreased the cell capacitance dose-dependently, which was in accordance with the increased rhodamine123 efflux rate.

Discussion: 

APAP-administration may reduce the bioavailability of co-administered drugs or/and nutrients through changes of intestinal cell membrane integrity and capacitance. The increase of membrane integrity could be as a result of reassembly of the tight junctions (TJ) because of modulations in the phosphorylation status of TJ proteins due to APAP. Also, it was observed that protein phosphatase inhibitors raise the TER value in the Caco-2 cell model (Seth et al. 2007). Besides, the decrease of cell capacitance could be as a result of a higher MDR1 activity.

Conclusion: 

Impedance spectroscopy together with the human cell barrier model Caco-2 is a promising non-invasive system for real-time monitoring of intestinal APAP effects. APAP may reduce the bioavailability of co-administered drugs or/and nutrients through changes in the net intestinal absorption. Prediction of in-vivo absorption based on in-vitro methodology helps reduce the number of animal experiments.

Keywords: 

Acetaminophen (APAP), Impedance, Transepithelial electrical resistance (TER), Caco-2 cell, intestinal barrier, multidrug resistance gene 1 (MDR1)

¹Seth et. al. Protein Phosphatases 2A and 1 Interact with Occludin and negatively regulate the assembly of tight Junctions in the caco-2 cell monolayer. The Journal of biological chemistry; Vol. 282, No. 15, 11487–11498, April 2007.