Equilibrium dialysis is commonly used in drug-plasma protein binding (PPB) studies to quantitate the free fraction of drugs in plasma. The binding of drugs to plasma proteins is a critical factor that affects their pharmacokinetics and pharmacodynamics, as only the free fraction of a drug can exert a physiological effect. The Thermo Scientific Pierce Rapid Equilibrium Dialysis (RED) Device is a superior method for conducting this analysis because it delivers accurate and consistent data with shorter preparation and dialysis times.

RED Devices use a size-defined dialysis membrane to quantitate the amount of free (active) drug molecules that are not bound to plasma proteins. They consist of disposable inserts and a base plate with a standard microplate footprint. The inserts are made of two side-by-side chambers separated by a dialysis membrane and are used along with a required base plate or are available as single-use plates with Inserts. Competition RED Devices are also available to enable competitive dialysis experiments with multiple tissue or protein fluid samples.

Features of RED Devices include:
• Ease of use—disposable tubes do not require presoaking, assembly, or specialized equipment
• Rapid dialysis—high surface-to-volume ratio of the membrane enables equilibrium in 2–4 hours
• High-throughput—96-well footprint is suitable for automation
• Multi-sample processing—can be used for 1–48 assays/plate without wasting an entire plate
• Robustness—compartmentalized design eliminates the potential for cross-contamination or leakage
• Reproducibility and accuracy—validated for plasma protein binding assays, producing results consistent with those reported in the literature
• Flexible format—available in pre-inserted disposable polypropylene plates and packs of individual inserts

In addition to plasma protein binding, the device is used for determining drug partitioning between red blood cells and plasma, protein binding of liver microsomes to improve the correlation between in vitro and in vivo intrinsic clearance, drug metabolism and pharmacokinetics (DMPK) assays, and competition between tissue protein binding against plasma proteins.

RED Device Inserts, 8K MWCO
Pierce RED Device Inserts are designed for use with a required base plate for equilibrium dialysis experiments. Each single-use, disposable insert is made of two side-by-side chambers separated by an O-ring-sealed vertical cylinder of dialysis membrane (8K MWCO) validated for minimal nonspecific binding. They are available in packs of 50 or 250 each and are useful for testing a variable number of samples per run.

RED Device Base Plates
Pierce RED Device Inserts are used with either the RED Device Reusable Base Plate made of high-grade PTFE (Teflon™) or the RED Device Single-Use Base Plate made of high-density polypropylene. The Single-Use Base Plate is disposable and lightweight, allowing routine automation. Each Base Plate holds up to 48 RED Device Inserts and has a standard 96-well plate footprint with 9 x 9 mm well spacing for compatibility with multichannel pipettors and automated liquid handling systems.

RED Device Single-Use Plate with Inserts, 8K or 12K MWCO
The RED Device Single-Use Plate with Inserts is composed of disposable high-density polypropylene and comes preloaded with 48 equilibrium dialysis membrane inserts. Each insert includes two side-by-side chambers separated by an O ring sealed vertical cylinder of dialysis membrane (8K or 12K MWCO). The device is automation-friendly and has a standard 96-well plate footprint with 9 x 9 mm well spacing. The single-use plate is easily disposed of to avoid contamination and cleaning, making it useful when performing PPB assays with radioactive or hazardous materials.

Competition RED Device Inserts and Base Plate, 12K MWCO
The Pierce Competition RED Device facilitates the analysis of simultaneous drug interactions and partitioning among multiple tissues to accurately model in vivo drug interactions. The system consists of disposable dialysis tube inserts (12K MWCO) and a reusable base plate made of chemically inert high-grade PTFE, eliminating non-specific binding and risk of contamination. The base plate is divided into different size chambers for positioning 2–8 RED Device Inserts per well, enabling competitive dialysis experiments with 2–15 separate tissue or protein fluid samples. Each Competition RED Insert contains either one or two separate dialysis chambers (each package includes both types).

Applications of the Competition RED Devices include:
• ADME-Tox studies: in vitro screening of drug partitioning between plasma and multiple tissues before in vivo studies with animal models
• Determine formulation of drug dosage for in vivo studies
• Drug-drug interaction studies
• Competitive binding and dissociation constant determination for small molecules versus multiple targets

RED Device Insert Removal Tool
This tool enables fast removal of 8 inserts at once.