An in vitro-in silico workflow for predicting renal clearance of environmental chemicals and drugs.

Accurate prediction of human renal clearance is essential for evaluating drug pharmacokinetics and environmental chemical risks, yet current methods often neglect rate-determining active transporter-mediated mechanisms. This study aimed to expand and validate a unified in vitro-in silico workflow for predicting renal clearance of both pharmaceuticals and per- and polyfluoroalkyl substances (PFAS) with varied elimination half-life ranges. We hypothesized that robust predictions of human renal clearance across diverse chemical classes can be achieved by combining human proximal tubule cell-based permeability/uptake assays with computational models of renal physiology. Human RPTEC/TERT1 cells and their OAT1-overexpressing variant were cultured in 96-well plates and Transwells to measure uptake, directional transport, and intracellular accumulation of 36 chemicals (28 PFAS, 7 drugs, 1 cosmetic ingredient). Time-course concentration data were used for either two-compartment (96-well) or three-compartment (Transwell) kinetic models. Permeability parameters were integrated into a physiologically-based kidney model for in vitro-to-in vivo extrapolation (IVIVE). A follow-up validation study with PFAS used independent experiments to derive similar predictions. Transwell-based three-compartment modeling yielded the most accurate absolute renal clearance predictions for rapidly eliminated drugs. For slowly cleared PFAS, simpler 96-well two-compartment modeling provided high correlation with observed human clearance, accurately distinguishing low-, medium- and high-clearance compounds; model predictions were consistently human health-protective. The PFAS validation study confirmed reproducibility of the approach. The proposed workflow is a conservative, scalable, mechanistically-informed and empirically-benchmarked approach for predicting renal clearance in humans. Transwell assays best support drug clearance estimation, whereas high-throughput 96-well formats enable reliable relative clearance ranking for PFAS, supporting both pharmaceutical development and environmental chemical risk assessment.