Because of the potentially lethal effects of unintended hERG block, the FDA has recommended that all compounds be functionally tested for this effect in an electrophysiological (patch-clamp) assay before being tested in humans. While this assessment of hERG channel function will remain the gold standard to assess hERG channel block, binding assays can be used in order to triage compounds and identify potential liabilities earlier in the process. The recently developed Predictor™ hERG Fluorescence Polarization Assay Kit provides a homogenous assay format that uses a fluorophore-labelled, hERG-binding protein as a tracer. Competition with hERG binding proteins in the sample, releases the tracer which then depolarizes emission light.
The PHERAstar® multifunctional HTS microplate reader provides a fast and sensitive platform to run this FP assay. It verified the usability of the assay as IC50 values matched those obtained from patch-clamp experiments.