What Is It?
Every drug that makes it to the pharmacy shelf must leap over numerous hurdles, starting with experimentation in the lab, followed by clinical trials in humans and culminating with the scrutiny of the U.S. Food and Drug Administration (FDA), which must review and approve all proposed new medications for safety and effectiveness before they can be sold to consumers.
A clinical trial uses human volunteers in planned research to increase medical knowledge. A trial look at an "intervention," such as a drug, medical device, procedure or participants' behavior (such as diet and exercise), to assess its merit. The researchers measure the effects of the intervention on the participants. The goal is to see if a new drug, device, procedure or behavioral modification is effective and safe.
For example, a clinical trial might look at the effects of a new drug on participants to see if it effectively and safely lowers high blood pressure.
There is another kind of clinical study, called an observational study, in which participants are also observed to assess health outcomes, but they are not assigned specific interventions, such as a drug or procedure. For example, researchers conducting an observational study might observe a group of older adults to see how exercise affects their cardiac health. (Find out more about observational studies.)
In the United States, research usually starts with lab experiments and sometimes with animal testing or computer modeling. This may be followed by clinical trials in humans.
Currently, more than 150,000 studies of drugs and other treatments are in active clinical trials in 185 countries. They may be done in cities and towns of any size and can be conducted at universities, community clinics, hospitals and doctors' offices.
The federal government maintains a website called ClinicalTrials.gov that provides information on publicly and privately funded clinical studies of drugs, diseases and conditions. The site has information about what trials are being conducted or coming up and which ones are seeking participants.
All clinical trials must have a study design plan called a protocol. This plan is presented to the U.S. Food and Drug Administration (FDA) as part of the Investigational New Drug (IND) application. The FDA and a research ethical review board or an institutional review board (IRB) must approve a protocol for each study site. After the study begins, the review board advocates for the volunteers. Anyone who volunteers to participate in a study must first sign a written informed consent, which says that you have been given information about the study and understand it. (Find out more about oversight of clinical trials and informed consent.)
Once a trial is completed, the results are examined by the FDA. Before approval is given, the clinical trial results of safety and effectiveness must be "statistically significant." That means the results are analyzed to show that they are highly likely to be "true" and not the result of chance.
The process can take more than 10 years, and many new products and procedures never make it through the process and never reach the market.
Pharmaceutical companies also test drugs that have been approved to continue checking long-term safety and effectiveness. If the company wants to market the drug for new uses or add labeling claims, more clinical trials are required.
Reasons for Conducting Clinical Trials
Any question a health care professional might have about how best to diagnose, treat or prevent a medical condition may be addressed scientifically by a clinical trial. For example, a study might ask whether using a particular drug in addition to surgery is better than surgery alone or whether earlier, more aggressive treatment of a condition produces a better outcome. Trials are often used to compare a new drug's safety and effectiveness to a placebo or to existing drugs used for the same purpose.
While some may have goals of testing potential cures for diseases or ways to prevent them, others may be aimed at improving quality of life for those living with a disease or condition.
Here are a few reasons for conducting clinical trials:
- Evaluating a way to treat or manage a disease or a condition, such as drugs, medical devices or approaches to surgery or treatment
- Finding ways to prevent development or recurrence of a disease or condition, such as testing new medicines, vaccines or lifestyle changes
- Evaluating ways to identify or diagnose a disease or condition
- Examining ways to identify a condition or the risk factors for that condition
- Looking for ways to improve the comfort and quality of life of people with a chronic illness and measuring the success of those methods
When a company or agency proposes a new drug or medical device, it usually conducts some trials using animals or computer models. If those results prove promising, it submits an Investigational New Drug (IND) application to the FDA asking to begin testing with humans in a clinical trial.
The IND includes a design plan called a protocol. This includes, for example, study locations; how long the study will last; how many people will participate; eligibility requirements; and a schedule of tests, procedures, medications and dosages.
Before the clinical trial can begin, the FDA and a research ethical review board or an institutional review board (IRB) must approve a protocol for each study site. The review board will advocate for the volunteers. Its job is to be sure that the clinical trial is designed to answer the scientific question and to assure participants' safety.
Many trials include multiple "arms," or groups of participants who are given different treatments for the purposes of comparison. One group might receive an experimental drug, while another receives a standard treatment or a placebo.
Some words you may hear used to describe clinical trials include:
- Open-label: A drug trial in which both the researchers and the volunteers know what drug is being administered and at what dose. It is also called a non-blinded trial. Sometimes such studies are conducted while a drug is awaiting review; during that period, participants or insurers may be required to pay the wholesale cost of the medication.
- Placebo-controlled: A trial in which some participants are given the drug that's being tested and others are given a placebo, or inactive compound. A placebo can have many forms. In addition to the familiar pills, a placebo may be an injected saline (inactive) solution in the case of an injected or infused drug or an inactive cream or nasal spray. The placebo will look exactly like the experimental medication.
- Double-blinded or double-masked: Usually participants don't know if they're receiving the treatment being tested or not. Such studies are termed single-blinded. But in some cases, health care providers also don't know which group is receiving the drug and which a placebo. These studies are called "double-blinded."
- Randomized: A randomized trial is one in which participants are randomly selected for either the experimental group or the control group. Often, researchers use a computer program to determine who goes into which group. Neither the researcher nor the volunteer has any input or control into which group you enter.
Phases of Clinical Trials
Clinical trials have several phases. The initial trials, usually small (20 to 80 volunteers), are called Phase I trials. Some Phase I trials use the same dose of a drug throughout the trial, but others may increase the dose to determine the maximum safe dosage and to discover what, if any, side effects result as the dose is increased. Additionally, researchers sometimes take note of effectiveness data gathered during Phase I trials: Did participants stabilize or get better? The primary purpose of these studies is to measure the drug's safety.
In Phase II trials, researchers again look at safety, but also gather data on effectiveness. Some Phase II trials compare the drug to existing treatments, others to a placebo. Phase II trials target volunteers with a specific disease to evaluate the potential benefits of the new drug in this select population. Phase II trials are usually larger than Phase I studies and may include up to several hundred participants.
Phase III trials are the make-or-break tests of effectiveness and safety and the first time the drug (or other intervention) is used in a broad population. These trials gather additional information on the overall risk-benefit relationship. The results of Phase III trials also affect FDA labeling of a drug or device. These studies may recruit from 1,000 to 3,000 participants and are designed to evaluate effectiveness, compare the experimental treatment to other treatments (if any) or placebo and monitor safety. Because Phase III trials are so much larger than other studies, they provide the best data on overall effectiveness and safety of the treatment.
Phase IV trials are conducted after the FDA grants marketing approval. These studies can provide valuable insight on the effects of long-term use of a treatment or procedure in the general population. They can be designed to accomplish many things. Some are ongoing safety trials, some are registry trials examining the long-term impact on a disease process and others look at the cost/benefit analysis.