Abstract
Nitrogen-containing heterocycles (N-Hets) are among the most prevalent and versatile structural motifs in pharmaceuticals, serving as key scaffolds in over 85% of biologically active small molecules. Their structural diversity and functional versatility have made them integral components of both U.S. Food and Drug Administration (FDA) approved and investigational drug molecules, modulating biological activity across a range of molecular targets. In 2025, the FDA approved 26 small-molecule drugs featuring N-Het frameworks, spanning multiple therapeutic areas, including oncology, metabolic disorders, infectious diseases, and rare/orphan conditions. This review offers a comprehensive overview of these newly approved compounds, emphasizing their biological activity and synthetic approaches. Special attention is given to drug-target interactions, focusing on receptor binding and highlighting the important role of N-Hets in medicinal chemistry. By exploiting the intrinsic chemical properties of N-Hets and leveraging modern synthetic methodologies, these scaffolds continue to drive the discovery of therapeutically relevant molecules, highlighting their sustained significance in modern drug discovery.