Pyridine

Pyridine is the single most frequently occurring nitrogen heterocycle in FDA-approved small-molecule drugs approved since 2013, present across a broader range of therapeutic areas than any other ring system in contemporary drug discovery. Among pyridine-containing drugs approved over the past decade, the anticancer category dominated with 33% of approvals, followed by CNS agents at 20%, reflecting the scaffold's particular utility in kinase inhibitor and neurological drug programmes. The ring offers a well-balanced combination of aromatic stability, moderate basicity, and a single nitrogen atom that functions as a hydrogen bond acceptor capable of engaging productively with protein binding sites, hinge regions, and allosteric pockets. The C-H positions of the pyridine ring provide systematic handles for regioselective functionalisation via cross-coupling, C-H activation, and SNAr reactions, enabling efficient exploration of structure-activity relationships, while the ring nitrogen also serves as a metabolic soft spot that can be exploited or mitigated through strategic substitution and fluorination. The scaffold functions as a bioisostere for phenyl and other heteroaromatic rings, frequently used in lead optimisation to improve aqueous solubility, reduce CYP-mediated metabolism, and modulate pKa without sacrificing binding affinity.

The broad number of FDA- approve molecules containing Pyridine include: Sotorasib (Lumakras, Amgen), a first-in-class oral covalent KRAS G12C inhibitor built around a pyrido[2,3-d]pyrimidinone core bearing a dialkylpyridin-3-yl substituent that controls the compound's atropisomeric geometry, approved in May 2021 as the first targeted therapy for KRAS-mutant NSCLC. Lenacapavir (Sunlenca, Gilead) is a first-in-class HIV-1 capsid inhibitor whose molecular architecture incorporates a central pyridine ring connecting the indazole and alkyne pharmacophoric elements, approved in December 2022 for adults with multidrug-resistant HIV-1 infection and notable for its twice-yearly subcutaneous dosing regimen.