by Liz Allen, Visiting Professor, Faculty of Life Sciences and Medicine, King’s College London and Quintiles, Early Clinical Development
What is a clinical trial?
Clinical trials are studies designed to evaluate the effectiveness and safety of potential new medicines. Clinical trials are divided into four phases (Phase I, II, III and real world late phase studies sometime called Phase IV).
Phase 1 requires a small number of subjects, usually healthy volunteers though more recently such studies involve small numbers of patients. As the development moves from phase to phase increasingly large numbers of patients become involved and the cost escalates. It is estimated that about 40% to 50% of drugs that enter phase III studies will fail, by which point a pharmaceutical company will have invested close to one billion pounds. Read more Adaptive clinical trials – could patients benefit?