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.