# An In Silico Transwell Device for the Study of Drug Transport and Drug–Drug Interactions

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## Abstract

### Purpose

Validate and exemplify a discrete, componentized, in silico, transwell device (ISTD) capable of mimicking the *in vitro* passive transport properties of compounds through cell monolayers. Verify its use for studying drug–drug interactions.

### Methods

We used the synthetic modeling method. Specialized software components represented spatial and functional features including cell components, semi-porous tight junctions, and metabolizing enzymes. Mobile components represented drugs. Experiments were conducted and analyzed as done *in vitro*.

### Results

Verification experiments provided data analogous to those in the literature. ISTD parameters were tuned to simulate and match *in vitro* urea transport data; the objects representing tight junction (effective radius of 6.66 Å) occupied 0.066% of the surface area. That ISTD was then tuned to simulate pH-dependent, *in vitro* alfentanil transport properties. The resulting ISTD predicted the passive transport properties of 14 additional compounds, individually and all together in one in silico experiment. The function of a two-site enzymatic component was cross-validated with a kinetic model and then experimentally validated against *in vitro* benzyloxyresorufin metabolism data. Those components were used to exemplify drug–drug interaction studies.

### Conclusions

The ISTD is an example of a new class of simulation models capable of realistically representing complex drug transport and drug–drug interaction phenomena.

## Key words

agent-based modeling discrete event drug transport drug–drug interaction emergent properties simulation## Abbreviations

- CYP
a P450 enzyme

- ISTD
in silico transwell device

- MW
molecular weight

- PCP
physicochemical properties

- PRN
pseudorandom number

- SM
supplementary material

- TD
transwell device

## Notes

### Acknowledgment

This research was funded in part by grant R21CDH00101 from the CDH Research Foundation (of which CAH is a trustee). We thank Professors John Verboncoeur and George Sensabaugh for encouragement. We thank the members of Biosystems Group for helpful discussions, with special thanks going Teddy Lam, Sean Kim, Mark Grant, and Li Yan for commentary on the manuscript, to Sunwoo Park for technical support, and Glen Ropella for his support and keen technical and theoretical insights.

## Supplementary material

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