The branch of science that deals with the discovery and development of drugs. Those working in it (pharmacologists, doctors, scientists and laboratory technicians) determine the chemical structure and composition of drugs and how these act in the body. They assess the use of drugs in the prevention and treatment of diseases, their side-effects and likely toxicity. This work takes place in universities, hospitals and, in particular, the pharmaceutical industry. The last of these has expanded tremendously during the 20th century and in Britain it is now one of the largest business sectors, not only providing the NHS with most of its pharmaceutical requirements but also exporting many medicines to other countries.

Pharmacologists not only research for new drugs, but also look for ways of synthesising them on a large scale. Most importantly, they organise with clinicians the thorough testing of drugs to ensure that these are safe to use, additionally helping to monitor the effects of drugs in regular use so as to identify unforeseen side-effects (MEDICINES).