In cystic fibrosis research, people often talk about Phases I, II, III and IV. What do these phases refer to? Should candidates applying to take part in such research take them into consideration?
. In clinical research, studies are classified under Phases I, II, III and IV. Phase I studies evaluate the safety of a drug. They are conducted on a small number of healthy volunteers, and are used to evaluate what happens to the drug in the human body. The side effects are, therefore, closely examined.
Phase II studies involve a larger number of people and provide information on the way a drug functions, as well as its benefits and side effects. These are randomized, double-bind studies, which means that one group of patients is given the new drug and the other group is given the standard drug or a placebo (inert substance). Neither the patients nor the researchers who work directly with the patients know which group has been given the new drug until the study is completed.
Phase III studies are somewhat similar to Phase II studies, except that they include a much greater number of people (thousands) and can last for years. These studies give researchers a good idea of the effectiveness, benefits and side effects of a new drug. These are also usually randomized, double-blind studies. Following successful completion of a Phase III study, the pharmaceutical company that developed the new drug can file an application to the government for marketing approval.
Once a new drug hits the market, Phase IV studies are often conducted. The purpose of these studies is to evaluate the drug’s long-term benefit and to compare the cost-benefit ratio with that of the traditional treatment. Phase IV studies can also determine whether the drug has any other innovative uses.