RT Journal Article
SR Electronic
T1 Evaluation of In Vitro Models for Assessment of Human Intestinal Metabolism in Drug Discovery
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 1169
OP 1182
DO 10.1124/dmd.120.000111
VO 48
IS 11
A1 Davies, Mari
A1 Peramuhendige, Prabha
A1 King, Lloyd
A1 Golding, Melanie
A1 Kotian, Apoorva
A1 Penney, Mark
A1 Shah, Syeda
A1 Manevski, Nenad
YR 2020
UL http://dmd.aspetjournals.org/content/48/11/1169.abstract
AB Although intestinal metabolism plays an important role in drug disposition, early predictions of human outcomes are challenging, in part because of limitations of available in vitro models. To address this, we have evaluated three in vitro models of human intestine (microsomes, permeabilized enterocytes, and cryopreserved intestinal mucosal epithelium) as tools to assess intestinal metabolism and estimate the fraction escaping gut metabolism (fg) in drug discovery. The models were tested with a chemically diverse set of 32 compounds, including substrates for oxidoreductive, hydrolytic, and conjugative enzymes. Liquid chromatography–high-resolution mass spectrometry was used to quantify substrate disappearance [intrinsic clearance (CLint)] and qualify metabolite formation (quantitative-qualitative bioanalysis). Fraction unbound in the incubation (fu,inc) was determined by rapid equilibrium dialysis. Measured in vitro results (CLint and fu,inc) were supplemented with literature data [passive Caco-2 apical to basolateral permeability, enterocyte blood flow, and intestinal surface area (A)] and combined using a midazolam-calibrated Qgut model to predict human fg values. All three models showed reliable CYP and UDP-glucuronosyltransferase activities, but enterocytes and mucosa may offer advantages for low-clearance compounds and alternative pathways (e.g., sulfation, hydrolases, and flavin-containing monooxigenases). Early predictions of human fg values were acceptable for the high-fg compounds (arbitrarily fg > 0.7). However, predictions of low- and moderate-fg values (arbitrarily fg < 0.7) remain challenging, indicating that further evaluation is needed (e.g., saturation effects and impact of transporters) but not immediate compound avoidance. Results suggest that tested models offer an additional value in drug discovery, especially for drug design and chemotype evaluation.Significance Statement We found that cellular models of the human gut (permeabilized enterocytes and cryopreserved intestinal mucosa) offer an alternative to and potential advantage over intestinal microsomes in studies of drug metabolism, particularly for low-clearance compounds and alternative pathways (e.g., sulfation, hydrolases, and flavin-containing monooxigenases). The predictivity of human fraction escaping gut metabolism for common CYP and UDP-glucuronosyltransferase substrates based on the Qgut model is still limited, however, and appropriate further evaluation is recommended.