Medicines

How QT Prolongation, hERG Blockade, and Drug Interactions Forced a Regulatory Reset In the late 1990s, two blockbuster “non-sedating” antihistamines—terfenadine (Seldane) and astemizole—were pulled from the market after being linked to QT interval prolongation and torsades de pointes, a rare but often fatal heart rhythm disturbance.

Headlines buzzed about azelastine, a simple allergy spray that showed promise in cutting COVID infections. That’s the magic of drug repurposing:  Take an old medicine, give it a new job, and skip years of costly R&D. But here’s the truth no one puts on the slide deck: Repurposing only works if toxicology is in the driver’s seat.