Last updated: 04 October 2011
Before a medicine can be licensed, the manufacturer must first apply to the Medicines and Healthcare products Regulatory Agency (MHRA, see Useful links) for permission to test its drug through clinical trials. These are research studies in which the safety and effectiveness of medicines are carefully tested using strict criteria.
The largest sponsor of clinical trials in Britain is the pharmaceutical industry, although valuable medicines research is also carried out by research charities, research councils and the NHS. A quarter of the world’s top 100 medicines were developed in this country, which is a leader in clinical research.
Finding and developing a new medicine is a lengthy process, taking an average of 12 years. And it does not come cheap. It typically costs about £500million to develop a new medicine, from its discovery to gaining a licence.
Stages of research
There are four levels of clinical trials that are used to investigate a new medicine:
- Phase 1 The medicine is tested in small numbers of healthy volunteers (often 50 to 100) to find out how it works in the body and whether side effects increase at higher doses.
- Phase 2 The medicine is tested in moderate numbers of patients (200 to 400) with a particular condition or disease to see how effective it is and to identify common, short-term side effects.
- Phase 3 Information is gathered from a larger number of patients (often several thousand), to see how well it works and how safe it is.
- Phase 4 The medicine is monitored on an ongoing basis in post-marketing studies in real world conditions (possibly in several thousands of patients), after it has been licensed, to see if any unexpected side effects occur or if the medicine causes problems in certain sub-groups of people.
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