Predicting the potential for organic cation transporter 1-mediated drug–drug interactions with fenoterol by amitriptyline, fluoxetine, selegiline, metformin, and verapamil

An <i>in vitro</i> OCT1 inhibition assay using fenoterol as probe substrate was validated and identified that verapamil may pose a clinically relevant interaction risk, predicting a minimum 2-fold increase in fenoterol exposure. This highlights the need for caution when coadministrating verapamil with fenoterol and supports incorporating OCT1 inhibition profiling into preclinical evaluation of new drug entities to better inform clinical development and ensure patient safety.