Plasma contains between 6 and 8% protein including serum albumin and α-1-acid glycoprotein.

Plasma protein binding of a compound influences its distribution in the body

Bound compounds are retained in the blood and cannot cross biological membranes.

Plasma protein binding can be measured using Thermo Scientific's "RED Plate" system. It is a plate made up of 48 equilibrium dialysis inserts. Each insert consists of two compartments separated by a sealed, cylindrical and vertical dialysis membrane, with a cut-off of 12 kDa.


MatrixMouse plasma and PBS pH 7.4
Test concentration1µM
Test temperature37°C
Incubation time4h
Controlsverapamil et antipyrin
Analysis methodLCMS-MS
Data deliveryFraction bound to plasma protein


Compoundfraction bound
Propranolol90 %
Quinidine60 %
Metoprolol18 %
Piroxicam98 %

Plasma protein binding measured at 37°C in mouse plasma