PHARMACOLOGICAL ONOMASTICS: WHAT'S IN A NAME?

Pharmacology has traditionally classified drugs based on their primary receptor target and a binary view of their action—typically as agonists or antagonists. However, this nomenclature is increasingly strained by the discovery that drugs can exhibit 'collateral' or 'pluridimensional' efficacy. As our ability to detect subtle changes in cellular function improves, it has become clear that a single ligand can stabilize distinct receptor conformations, leading to selective activation of specific signaling pathways (such as G-protein vs. beta-arrestin pathways) while leaving others unaffected. This phenomenon, often termed biased agonism or functional selectivity, means that a drug's classification can change depending on the specific cellular system or pathway being measured.

Drug behavior is rarely absolute; it is often dependent on the biological system in which it is tested. For instance, a molecule might act as a full agonist in one cell type but a partial agonist or antagonist in another, depending on receptor density or the efficiency of receptor coupling. Furthermore, the rise of allosteric modulators—which bind to sites distinct from the orthosteric site—adds another layer of complexity. Because these modulators interact with the receptor in a way that is dependent on the co-binding ligand, their effects are inherently probe-dependent, making simple labels like 'antagonist' inadequate.

Accurate nomenclature is not merely an academic exercise; it biases how researchers and clinicians understand and utilize drugs. If a drug is mislabeled based on an incomplete understanding of its efficacy, its therapeutic potential may be misunderstood, or its side effects may be misattributed. The author argues that we need a more comprehensive approach to drug taxonomy that accounts for these nuances. By characterizing the full range of a molecule's efficacies across multiple signaling pathways, researchers can better link specific pharmacological properties to clinical phenotypes, potentially leading to more precise and effective therapeutic interventions.