Research

Phases of Clinical Research

If you are not familiar with the four phases of clinical research, you may wish to begin by reading the following excerpt from the WHO’s Medical Ethics Manual.

• Phase one research, usually conducted on a relatively small number of healthy volunteers, who are often paid for their participation, is intended to determine what dosage of the drug is required to produce a response in the human body, how the body processes the drug, and whether the drug produces toxic or harmful effects. 
  
• Phase two research is conducted on a group of patients who have the disease that the drug is intended to treat. Its goals are to determine whether the drug has any beneficial effect on the disease and has any harmful side effects.  These are sometimes referred to as "proof of concept" trials, i.e., trials showing possible efficacy in the clinical condition under study.
  
• Phase three research is the clinical trial, in which the drug is administered to a large number of patients and compared to another drug, if there is one for the condition in question, and/or to a placebo. Where possible, such trials are ‘double-blinded’, i.e., neither research subjects nor their physicians know who is receiving which drug or placebo.  The FDA requires two such "pivotal study" phase III trials showing efficacy.
  
• Phase four research takes place after the drug is licenses and marketed. For the first few years, a new drug is monitored for side effects that did not show up in the earlier phases. Additionally, the pharmaceutical company is usually interested in how well the drug is being received by physicians who prescribe it and patients who take it.