Can we predict drug permeability class in intestinal epithelial cells using in situ live-cell ATR-FTIR spectroscopy?

Membrane permeability plays a vital role in oral drug absorption and is one of the important reasons for attrition of promising drug candidates in early-stage drug discovery. Conventional in vitro permeability assays and metabolomics-based approaches are informative but are often destructive, labor-intensive, costly and limited to endpoint measurements. Here, we report a live-cell attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy platform for label-free, cost-effective, non-destructive monitoring of biochemical responses in Caco-2 cells following exposure to model drugs spanning multiple Biopharmaceutics Classification System (BCS) classes.

IR spectra in the biochemical fingerprint region (1800-950 cm^-1) were then analysed using principal component analysis and hierarchical clustering. Distinct spectral signatures were observed for highly permeable versus poorly permeable compounds, with discriminatory features dominated by protein (amide I/II), lipid and phosphate-associated bands. Drugs that highly permeate through membranes left a clearly different spectral trail compared to those that do not. Importantly, chemometric separation was achieved within the early hours of exposure, demonstrating the potential of live-cell ATR-FTIR spectroscopy as a rapid, low-cost and non-destructive complement to conventional permeability screening assays.

These findings support the use of in situ live-cell ATR-FTIR spectroscopy as a promising approach for predicting drug permeability class in intestinal epithelial cells during early drug discovery.