Drug-based optical agents: infiltrating clinics at lower risk.

Fluorescent agents with specificity to cellular and subcellular moieties present promise for enhancing diagnostics and theranostics, yet challenges associated with regulatory approvals of experimental agents stifle the clinical translation. As a result, targeted fluorescent agents have remained predominantly as preclinical imaging tools. We discuss the potential of using optically labeled drugs to accelerate the clinical acceptance of optical and optoacoustic agents, in analogy to nuclear medicine approaches. This strategy, corroborated with microdosing studies, outlines a promising approach for overcoming bottlenecks and advancing photonic clinical imaging.