About Clinical Trials
What is a clinical trial?
There are many different types of trials and designs of studies. All new drugs have to go through a series of phases to test if they are safe and to test if they are effective.
Phase I Trials
Phase I trials aim to test the safety of a new treatment. This includes looking at side effects of a treatment. Phase 1 trials involve only a very small number of people, usually healthy volunteers.
Phase II Trials
Phase II trials test the new treatment in a larger group of people who have an illness, to see whether the new treatment is effective, at least in the short term. Usually a few hundred people are involved at this stage. Phase II trials also look at safety.
Phase III Trials
Phase III trials test the new treatment in a larger group of people with an illness. Phase III trials compare the new treatment with the treatment currently in use, or occasionally with a placebo. These trials look at how well the new treatment works and at any side effects. They usually go for longer than Phase II trials, typically a year or more, and are larger, often involving several thousand patients from different countries. Treatments only move into Phase III if Phases I & II have been successful.
After successfully completing this phase of testing, an application to the regulatory authorities can be made to make the treatment available for sale.
