What are clinical trials?

Clinical trials are often done in a "randomized" way. These are sometimes called RCTs for "randomized clinical trials." In an RCT, some people will be chosen at random to receive a treatment or intervention, such as a new drug. The rest of the participants will be given a "placebo," such as a sugar pill. In other cases, when two interventions are being compared, one group will receive one of the interventions and the other group will be given a different one. Some clinical trials are also "blinded." This means that both the volunteers and the doctors do not know if people are taking the new medicine or the placebo. Only at the end of the study will this be revealed. Since people are chosen at random (similar to a coin toss) in an RCT, people who receive the treatment should be no different than those who do not. For instance, there should be an equal number of males who receive treatment compared with those who do not. This helps reduce bias due to something like gender in a study.

New drugs are first developed in research labs, and then tested in animals. Only then are clinical studies done in humans. Clinical trials of new drugs are done in different phases:

  • Phase I studies test a new drug for the first time in a small group of people (about 20-80) to see if it safe, to find the right dose, and to know the side effects.
  • Phase II studies are done in more people (about 100-300) to see how well the new drug treats a disease.
  • Phase III studies are done in large groups of people (about 1000 to 3000) to see if the new drug works well, has side effects, and how it compares to other drugs.
  • Phase IV studies are done after the treatment is approved by the U.S. Food and Drug Administration (FDA).
Fdanewdrugreviewprocess-thumb
In the United States, drugs must be approved by the Food and Drug Administration (FDA). The FDA requires three phases of research studies before a drug can be prescribed or sold to the public. This figure shows how complex the approval process is.

Often it is also very important to keep studying the drug after it has gone to market. This is the fourth phase of studies required by the FDA. When the approved drug is being taken by more people over a longer period of time, more information can be gathered.