Which assay type screens for abuse potential through receptor-ligand interactions?

• A. In vitro metabolism by CYP enzymes
• B. QT prolongation screening
• C. Genotoxicity
• D. Receptor-ligand binding assays

Answer: (D)

Receptor-ligand binding assays measure whether a substance can attach to a target receptor and how tightly it binds. This directly informs abuse potential because many drugs of abuse exert their psychoactive effects by engaging brain receptors that control reward and mood. In these assays, a known labeled ligand binds the receptor, and the test compound competes with it. If the compound displaces the labeled ligand, it indicates binding and yields an affinity value (like Ki) that helps gauge how likely the compound is to produce receptor-mediated effects. The other options assess different safety aspects—metabolism by CYP enzymes looks at clearance and interactions, QT prolongation screens cardiac repolarization risk, and genotoxicity tests DNA damage. So, probing direct receptor interactions is the way to screen for abuse potential.