Most drugs are small organic chemicals
Many drugs are small molecules that bind to speciﬁc structures in or on our cells. Our cells have numerous specialist functions, regulated by instructions from CH3 genes. The drug molecules alter these processes, subtly changing cell biochemistry.
Herbs and minerals were used in ancient cultures. During the European Renaissance, apothecaries experimented with plants retrieved from the Americas by explorers, such as the bark of the quina tree. This contains quinine, used to treat malaria.
Even when an active ingredient had been identiﬁed, doctors rarely knew how it actually worked. A profound change came when researchers began to use an understanding of the molecular basis of human physiology to develop new drugs – so-called rational drug design.
Sir James Black was behind two major drug families: beta-blockers, to treat coronary heart disease, and drugs that block histamine receptors, which are used to treat stomach ulcers. He introduced a new way of thinking to drug development. Black’s approach involved understanding how cells use messenger molecules to communicate with each other. By adapting these natural processes, he was able to develop analogues that bound to the same targets but stopped them working.
Small is beautiful
Drug companies have preferred to create drugs from small molecules. This should make them easy to synthesise, modify and characterise, as well as more likely to reach their targets in the body. They can generally be given in pill form. A small, stable molecule is easier to quality assure, and scaling up to full production is more straightforward.