Medicinal chemistry is concerned with the design and synthesis of biologically active molecules. It aims at creating new chemical structures to better understand and influence physiological and/or pathological systems. Ultimately, it allows the discovery and optimization of novel drug candidates to address unmet medical needs, as exemplified by recent progress in the treatment of cancer, cardiovascular or infectious diseases.
Although organic chemistry plays a fundamental role, current medicinal chemists work in a highly interdisciplinary environment and strongly interact with scientists working in the fields of molecular biology, structural biology, pharmacology, physicochemistry, biochemistry, pharmacokinetics, pharmaceutical technology, toxicology, translational medicine experts and associated scientists. Developments in these domains have had major impacts on the scope of medicinal chemistry and its ability to drive drug discovery.
The term medicinal chemistry appeared in the literature soon after World War II. At that time, the change from animal pharmacology to molecular pharmacology made it possible to express the biological activity of a compound as a quantifiable molecular property (e.g. IC50, EC50, pA2), and scientists started to use the term “drug design”. Soon thereafter the introduction of computers made it possible to study structure-activity relationships in a quantitative sense, and rational drug design seemed within reach.
In the following years developments accelerated: radiolabeling made binding assays possible, and cell biology appeared, leading to the identification of new targets. The introduction of molecular biology enabled a revolution in the characterization of therapeutic pathways, and in the understanding of molecular mechanisms of drugs. Progress in analytical techniques, computer technologies and their application in molecular modeling approaches and screening methods drastically changed the scope of the discipline, expanding the possibilities of medicinal chemistry to provide new compounds with therapeutic potential.
Over the last decade, the scope of medicinal chemistry has broadened considerably, and the molecules it deals with now show an increasingly larger structural diversity, blurring the border to biochemistry. Beyond small synthetic ligands and natural products, medicinal chemists have now developed numerous examples of modified peptides and proteins, antibody drug conjugates, multifunctional molecular constructs or synthetic vaccines. Medicinal chemistry also expanded beyond drug optimization: at the earliest stages of drug discovery, it now provides molecular tools for therapeutic target identification and validation, to explore biological pathways, as well as to study toxicological mechanisms. In the latest phase of drug discovery and development, medicinal chemistry provides imaging ligands and diagnostic tools, to better understand diseases and facilitate the clinical evaluation of novel drugs.
These developments went along with technical advances in chemical biology, molecular modeling, analytical technologies and medicine. As a consequence, medicinal chemistry now plays a role at the forefront of medical, agrochemical and pharmaceutical research: it creates the tools that drive progress in emerging areas, as illustrated by recent developments in e.g. stem cell biology, advanced diagnostics or regenerative medicine.
 IUPAC defined Medicinal Chemistry in 1998 as ‘a chemistry-based discipline, also involving aspects of biological, medical and pharmaceutical sciences. It is concerned with the invention, discovery, design, identification and preparation of biologically active compounds, the study of their metabolism, the interpretation of their mode of action at the molecular level and the construction of structure-activity relationships’ (Glossary Of Terms Used In Medicinal Chemistry - IUPAC Recommendations 1998).