Human Pgp Vesicle Kit (HEK293-derived)

Is P-gp (ABCB1) assessment required by FDA and EMA for drug approval submissions?

Yes. P-glycoprotein (P-gp / MDR1 / ABCB1) is one of the transporters for which the FDA Drug Interaction Guidance (2017) and EMA Guideline on the Investigation of Drug Interactions (2013) require in vitro assessment as part of the standard DDI submission package for new molecular entities (NMEs) entering clinical development. Both agencies recommend the vesicular transport assay using P-gp-overexpressing inside-out membrane vesicles as the primary in vitro method to determine substrate and inhibitor status. P-gp positive substrate or inhibitor findings trigger further evaluation based on R-value calculations, which may require clinical DDI studies with reference inhibitors (e.g., rifampicin, itraconazole) before NDA or MAA submission.

What is the difference between the standard P-gp kit (C4PVK010) and the FluoPgp variant (C4PVK011)?

C4PVK010 is the standard vesicular transport kit compatible with all detection methods — radiolabelled substrates (³H-digoxin, ¹⁴C-NMQ), unlabelled substrates with LC-MS/MS quantification, and fluorescent substrates. C4PVK011 is a variant of the same kit that additionally includes the novel FluoPgp fluorescent substrate, which enables fluorescence-based P-gp transport measurement without the need for radioisotope labelling, radioactive waste management, or liquid scintillation counting equipment. C4PVK011 is particularly suited for laboratories without isotope handling licences or for high-throughput screening workflows where fluorescence plate readers are preferred. Both kits use the same P-gp vesicle preparation and are suitable for regulatory DDI data generation.

Which probe substrates and inhibitors are recommended for P-gp vesicular transport assays?

The most widely used probe substrates for P-gp vesicular transport assays are digoxin (³H-digoxin) and N-methyl-quinidine (NMQ), both cited in FDA and EMA guidance as validated P-gp probe substrates. Convallatoxin is used as an alternative probe substrate. For positive inhibitor controls, elacridar (GF120918) is the reference dual P-gp/BCRP inhibitor; verapamil and tariquidar are used as P-gp-selective inhibitors in concentration-response studies. The Cell4Pharma kit is compatible with all standard probe substrates and detection methods, including the FluoPgp fluorescent substrate available in C4PVK011.

Can the P-gp vesicle kit be used in a multi-transporter DDI panel alongside BCRP and BSEP?

Yes — and this is the standard practice in regulatory drug development. The FDA and EMA expect a complete transporter DDI dataset submitted alongside the clinical dossier, and P-gp is invariably assessed in parallel with BCRP (ABCG2) and BSEP (ABCB11), with MRP2 (ABCC2) added for compounds with hepatic or intestinal efflux relevance. Cell4Pharma’s full ABC transporter vesicle kit range — P-gp, BCRP, BSEP, MRP1, MRP2, MRP5 — shares a common assay format and buffer system, enabling parallel processing within the same experiment. The Human Control Vesicle Kit (C4PVK009) serves as the single negative control across all transporter assays in the panel.

What is the recommended negative control for P-gp vesicular transport assays?

The Human Control Vesicle Kit (C4PVK009) from Cell4Pharma is the recommended negative control for P-gp transport assays. Control vesicles are prepared from HEK293 cells under identical conditions to the P-gp-overexpressing vesicles but without transporter transfection — enabling direct comparison of ATP-dependent transport in the presence and absence of P-gp. This confirms that observed uptake is P-gp-specific rather than attributable to non-specific binding, passive uptake, or endogenous transporter activity. Using matched control vesicles is required for regulatory-grade data interpretation. Both the P-gp and Control Vesicle Kits are available via SeamlessBio for the DACH region.