Transporter Interactions

Creative Biolabs has successfully established a full range of testing services for sufficiently predicting drug-drug interaction potential using our unparalleled technique platform. Besides CYP and UGT investigation, we proudly present our transporter interaction assays aiming at minimizing undesired DDI liability during early lead optimization stage.

Drug-drug interactions are known to induce serious clinical consequences by disturbing normal metabolism process when multiple drugs are co-administrated. Except for key enzymes (like CYP, UGT), interference of essential transporters also contributes to DDI potency and exhibits considerable clinical relevance. However, transporter-mediated DDI is much more complex for following reasons:

• Transporters are heavily involved in multiple metabolism processes, including absorption, distribution, and excretion.
• Transporters are located on vast tissues and organs (such as small intestine, liver, kidney, blood-brain barrier), and they have different effects at different sites.
• Functional redundancy and complication: there is a broad spectrum of transporters and subfamilies with diverse and overlapping physiological functions. Hence, their multiplicity nature poses one great challenge.
• Both uptake transporters (mediating the transport of substances from outside into cells) and efflux transporters (exporting substances out of cells) need to be considered to assess overall effects.

Due to the significance of transporter-mediated DDI risks, a comprehensive profiling focusing on transporter-compound interactions are strongly recommended by regulatory agencies including FDA, EMA, and PMDA. To address this need, Creative Biolabs provides integrated transporter interaction analyzing service covering most major transporters involved in drug metabolism.

To fully illustrate transport-compound interactions, we must understand that a test substance can be either a transporter substrate (potential DDI victim) or a transporter inhibitor (potential DDI perpetrator). Creative Biolabs employs two assay systems: in vitro permeability assay to measure the accumulation of test articles in transporter-expressed monolayer or cells, thus evaluating if it is a substrate; and in vitro inhibition assay to measure the accumulation of probe substrates in the presence or absence of test articles, thus evaluating if it is an inhibitor. Concentration ranges can be customized, and the consequence will be monitored by LC-MS/MS.

Caco2 Permeability Assay

In vitro permeability assays with Caco-2 represents an initial step to estimate epithelial and endothelial permeability as well as intestinal absorption. Both active and passive transport can be detected. This assay can help to evaluate overall permeability and involvement of active transport in a bi-directional experiment.

Additionally, Creative Biolabs offer further investigation services using in vitro models of various specific transporters.

Uptake Transporter Assay

Most uptake transporters involved in drug ADME belong to SLC (solute carriers) superfamily. Uptake transporters available in Creative Biolabs including but not limited to:

• OATP: OATP1B1 (OATP-C, LST-1, SLCO1B1) and OATP1B3 (OATP-8, SLCO1B3)
• OCT: OCT1 (SLCO22A1) and OCT2 (SLCO22A2)
• OAT: OAT1 (SLC22A6) and OAT3 (SLC22A8)

Substrate and inhibition assay will be performed using human embryonic kidney cells (HEK293) transiently transfected with single or double uptake transporters.

Efflux Transporter Assay

The majority of human efflux transporters are members of ATP-binding cassette (ABC) superfamily, except multidrug and toxin extrusion (MATE) proteins, which belongs to SLC family. Efflux transporters available in Creative Biolabs including but not limited to:

• MDR1 (ABCB1, P-glycoprotein)
• MRP2 (ABCC2)
• BCRP (ABCG2)
• BSEP (ABCB11)
• Multidrug and Toxin Extrusion (MATE): MATE1 (SLC47A1) and MATE2-K (SLC47A2)

Substrate and inhibition assay will be performed using MDCKII cell monolayers expressing indicated efflux transporter.

Table 1. Characteristics of selected drug transporters

With a broad range of transporter choices and industry-accepted technology systems, Creative Biolabs is able to provide accurate and consistent results of transporter interaction potency as part of comprehensive in vitro DDI investigations. For more detailed information, please feel free to contact us or directly sent us an inquiry.

Figure 1. Human drug transporters types and distribution. (Giacomini and Huang 2013)

Reference

1. König J, Müller F, Fromm MF. (2013) “Transporters and drug-drug interactions: important determinants of drug disposition and effects.” Pharmacol Rev. 65(3):944-66.
2. Giacomini KM, Huang SM. (2013) “Transporters in drug development and clinical pharmacology.” Clin Pharmacol Ther. 94(1):3-9.

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