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. Author manuscript; available in PMC: 2022 Nov 28.
Published in final edited form as: Expert Opin Drug Metab Toxicol. 2021 Jun 15;17(8):903–921. doi: 10.1080/17425255.2021.1935867

Figure 1. In vitro to in vivo extrapolation (IVIVE).

Figure 1.

We perform that IVIVE using toxicokinetic (TK) modeling. TK models relate external dose to internal body concentration by describing “what the body does to the chemical”: absorption, distribution, metabolism, and excretion (ADME). For IVIVE of in vitro bioactive concentrations, we assume that bioactivity would occur in the body at a concentration equal to an in vitro bioactive concentration, and use TK modeling in reverse (that is, reverse dosimetry) to find the “equivalent dose” – an external dose that would produce the specified body concentration. While IVIVE broadly includes any use of in vitro data to predict phenomena in vivo, it is useful to distinguish between TK IVIVE (that is, the use of in vitro data to predict ADME) and toxicodynamic (TD) IVIVE, which includes the use of in vitro data to predict toxic effects in vivo.