Development of a high throughput equilibrium dialysis method

The identification of large numbers of biologically active chemical entitie s during high throughput screening (HTS) necessitates the incorporation of new strategies to identify compounds with drug-like properties early during the lead prioritization and development processes. One of the major steps in lead prioritization is an assessment of compound binding to plasma prote ins, because it affects both the pharmaco-kinetics and pharmacodynamics of the compound in vice. Equilibrium dialysis is the preferred method to deter mine the free drug fraction, because it is less susceptible to experimental artifacts. However, even low-volume standard equilibrium dialysis is curre ntly net amenable to the HTS format. Those considerations dictate the devel opment of a high throughput equilibrium dialysis device, without compromisi ng the analytical quality of the data. The present paper demonstrates succe ssful development of a 96-well format equilibrium dialysis plate, Plasma pr otein binding of three drugs, propranolol, paroxetine, and losartan,with lo w, intermediate, and high binding properties, respectively, were chosen for assay validation. The data indicate that the apparent free fraction obtain ed by this method correlates with the published values determined by the tr aditional equilibrium dialysis techniques. (C) 2001 Wiley-Liss, Inc, and th e American Pharmaceutical Association J Pharm Sci 90:580-587, 2001.