Solid-phase microextraction for assessment of plasma protein binding, a complement to rapid equilibrium dialysis.

Determination of plasma protein binding () is considered vital for better understanding of pharmacokinetic and pharmacodynamic activities of drugs due to the role of free concentration in pharmacological response. Solid-phase microextraction (SPME) was investigated for measurement of from biological matrices and compared with a gold standard approach (rapid equilibrium dialysis [RED]). SPME-derived values of correlated well with literature values, and those determined by RED. Respectively, average protein binding across three concentrations by RED and SPME was 33.1 and 31.7% for metoprolol, 89.0 and 86.6% for propranolol and 99.2 and 99.0% for diclofenac. This study generates some evidence for SPME as an alternative platform for the determination of PPB.