Medicinal chemistry

Medicinal or pharmaceutical chemistry is a scientific discipline at the intersection of chemistry and pharmacology involved with designing, synthesizing and developing pharmaceutical drugs. Medicinal chemistry involves the identification, synthesis and development of new chemical entities suitable for therapeutic use. It also includes the study of existing drugs, their biological properties, and their quantitative structure-activity relationships (QSAR). Pharmaceutical chemistry is focused on quality aspects of medicines and aims to assure fitness for the purpose of medicinal products.

Medicinal chemistry is a highly interdisciplinary science combining organic chemistry with biochemistry, computational chemistry, pharmacology, pharmacognosy, molecular biology, statistics, and physical chemistry.

Discovery
The first step of drug discovery involves the identification of new active compounds, often called "hits", which are typically found by screening many compounds for the desired biological properties. These hits can come from natural sources, such as plants, animals, or fungi. More often, the hits can come from synthetic sources, such as historical compound collections and combinatorial chemistry.

Recent developments in robotics and miniaturization have incredibly accelerated and automated the screening process. Typically, a company will assay over 100,000 individual compounds using a method called high-throughput screening (HTS), before moving to the optimization step.

Optimization
The second step of drug discovery involves the synthetic modification of the hits in order to improve the biological properties of the compound pharmacophore. The quantitative structure-activity relationship (QSAR) of the pharmacophore play an important part in finding lead compounds, which exhibit the most potency, most selectivity, best pharmacokinetics and least toxicity. QSAR involves mainly physical chemistry and molecular docking tools (CoMFA and CoMSIA), that leads to tabulated data and first and second order equations. There are many theories, being the most relevant Hansch's analysis that involves Hammett electronic parameters, Esteric parameters and logP parameters.


 * See also: ADME and Lipinski's Rule of Five

Development
The final step involves the rendering the lead compounds suitable for use in clinical trials. This involves the optimization of the synthetic route for bulk production, and the preparation of a suitable drug formulation.

Training in medicinal chemistry
Many workers in the field do not have formal training in medicinal chemistry. Graduate (postgraduate) level programs do exist in medicinal chemistry, but frequently the broader education in a chemistry graduate program can provide many of the skills needed.