Passive Membrane Transport Analysis of Drug Mixtures.

Membrane transport is fundamental to biological cells and is a major hurdle in the rational design of pharmaceuticals. To measure membrane transport in vitro, most methods focus on simple diffusion of a single analyte across nonbiomimetic interfaces. Membrane engineering has facilitated novel strategies for the reconstitution, characterization, and application of biomimetic membranes. Herein, we define drug mixture analysis, an in vitro, label-free HPLC-MS, droplet interface bilayer (DIB) method, to assess membrane transport of drug mixtures and delineate simultaneous transport mechanisms. We use our method to classify the permeability of drugs from a structurally diverse FDA-approved library. This deep analysis uncovered correlation between determined permeability classifiers and drug properties such as the hydrophobic retention time, hydrogen bond donor count, lipophilicity, and predicted gut absorption. Across higher mimetic membranes, passive transport was quantified under physiologically relevant variables such as pH, temperature, lipid composition, and, in the presence of proteins, the coexistence of facilitated diffusion and simple diffusion. Our results show that DIBs are physiologically relevant interfaces for investigating membrane transport mechanisms relevant to artificial cell systems and drug screening.