What Are Clinical Trials

What Are Clinical Trials

A clinical trial is an organized way of studying medical treatments for diseases. Medical treatments are medicines, devices or procedures. Clinical trials are research studies that help prove that medical treatments are safe and effective to use. They also can show whether one medical treatment is better than another.

At first, studies of new medicines are done in laboratories. If the medicine looks promising, it is then tested in animals. Usually, clinical trials are only started after the treatment is found to be safe in animals. Most clinical trials involve many people. This way, if the medical treatment is shown to be safe and effective, doctors will know what to expect in their patients.

Why Clinical Phases

Clinical trials of medications involve four phases.

Phase I clinical trials usually include between 20 to 80 healthy people. These clinical trials make sure a medication is safe.

Phase II clinical trials are done only after a medication is shown to be safe. Phase II clinical trials involve no more than a few hundred participants who have the disease that the medication is intended to treat. These clinical trials are used to learn if the medication works and determines what dose should be used for the disease.

Phase III clinical trials can include up to several thousand participants. These clinical trials try to further confirm that the medication works for a specific disease. Phase III clinical trials also study the side effects of the medication. Both Phase II and Phase III clinical trials may compare the effectiveness of a new medication to a control group, who gets the standard treatment (or placebo). After a Phase III clinical trial is completed, data from some of the clinical trials can be sent to the Food and Drug Administration (FDA). If the FDA decides that the medication is safe and effective to use, it can then be marketed and prescribed by your doctor.

Phase IV clinical trials may be done, once a medication is marketed. Phase IV clinical trials often include several thousand participants. These clinical trials provide additional information about the medication's effectiveness and safety. Specifically, these trials continue to collect information on the long-term side effects of a marketed medication. This information is later sent to the FDA.

Medical and surgical procedures, herbal remedies, and dietary supplements are less regulated and do not go through this process.

How Clinical Trials Work

Generally, there are two types of clinical trials, uncontrolled and controlled. In an uncontrolled clinical trial, all participants simply receive the same treatment. However, these types of trials do not provide as much information as a controlled clinical trial.

In a controlled clinical trial, participants are divided into two groups. The first group, called the treatment group (or experimental group) may receive one or more kinds of treatment. The other type of group, called the control group, receives the standard treatment. Sometimes in medical trials, there is no standard treatment so a placebo or "sugar" pill is used. By dividing participants into groups, doctors can compare how well different treatments work.

An important part of a controlled clinical trial is that participants are randomly assigned to one of the two groups (see Figure). A participant who is randomly assigned means he or she is assigned to a group by chance (like a flip of a coin). A randomized clinical trial is the best way to study new treatments.

Often controlled clinical trials are also masked. There are two types of masked clinical trial designs, single masked and double masked. In a single masked clinical trial, participants do not know whether they received the new treatment or a standard treatment (or placebo) until the end of the study. In this type of clinical trial, the doctor and nurse know which treatment the participant received. In a double masked trial, neither the participant nor the doctor/nurse know whether the participant received the new treatment or a standard treatment (or placebo) until the end of the study. These clinical trial methods are important because they prevent people's behaviors or opinions from influencing the results of the clinical trial.