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Clinical Trials : What They Are and How They Work

Dr. Mario Trucillo

Last updated: November 22, 2016 3:17 pm

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In an earlier post, we highlighted the four part process of how new drugs are approved and monitored by the FDA.  From the discovery of a drug to how the FDA monitors safety once the drug comes to market, it was a general overview of a process. However, as you may know, the parts of that process are quite complex.  An integral component of bringing a new drug or treatment to market are clinical trials.

What Are Clinical Trials?

Clinical trials, also known as clinical studies, test potential treatments in human volunteers to see whether they should be approved for wider use in the general population.  Treatments may refer to new drugs, new combinations of drugs, new surgical procedures or devices, or biologic, such as a vaccine, or gene therapy. The goal of clinical trials is to determine if a new test or treatment works and is safe.  As mentioned in the earlier post about drug approval, treatments must first be studied in laboratory animals to determine potential toxicity before they can be tested in humans.  Treatments that are considered safe can then be moved into clinical trials. 1 

Different Types of Clinical Trials 2

There are different types of clinical trials depending on what type of treatment is being studied.  These are categorized as:

  • Treatment trials:  test new treatments, new combinations of drugs, or new approaches to surgery or radiation therapy.
  • Prevention trials:  look for better ways to prevent disease in people who have never had the disease or to prevent a disease from returning.
  • Diagnostic trials:  are conducted to find better tests or procedures for diagnosing a particular disease or condition.
  • Screening trials:  test the best way to detect certain diseases or health conditions.
  • Quality of Life trials (or Supportive Care trials): explore and measure ways to improve comfort and the quality of life for individuals with a chronic illness.

Usually, clinical trials compare a new product or therapy to something else to see if it works as well or better to treat or prevent a disease or condition. Some studies compare the test product to an existing therapy, while other compare the new drug to a placebo (a compound with no therapeutic action).  In some cases, it is unethical to include a placebo if an effective treatment is available.  Either way potential participants are told before they enter a trial whether placebos are going to be used in the study.2

How Clinical Trials Work

Each clinical trial is conducted under a plan called a “protocol” that is carefully designed to answer specific research questions.  The protocol describes who is eligible to participate in the clinical trial, the details of the drugs that are used and dosages, procedure, what information will be gathered, and the length of time of the study. Members of the research team led by a principal investigator regularly monitor the participants’ health to determine the treatment’s safety and effectiveness. Each clinical trial in the United States must be approved and monitored by an Institutional Review Board (IRB) to ensure that the risks are minimal to the participant and are worth any potential benefits. This review board is an independent committee that ensure that clinical trials are ethical and that the rights of participants are protected. 3

Once the protocol is approved, the drug can then move into clinical trials and potential participants are screened based on the criteria set in the protocol.  The participants for clinical trials are made up of a group of volunteers and vary depending on the type of clinical trial, the drug or treatment being studied, and other criteria involved depending on the specific information intended to be gathered.  The volunteers that qualify and are included in the study are then put through a process called randomization.  Randomization assures that treatment selection will be free of any preference a physician may have. Along with randomization, a feature known as blinding helps ensure that bias doesn’t distort the conduct of a trial or the interpretation of its results.  Blinding means that a participant is unaware if they are in a treatment group or a “control” group (someone who receives a placebo or a comparable treatment).3

Clinical Trials Are Conducted in 4 Phases 4

Clinical Trials are organized into sections called phases. These “phases” have different characteristics and requirements that need to be met in order to be considered that phase as the drug or treatment progresses towards approval.

Phase 1 trials determine dosing, document how a drug is metabolized and excreted, and identify acute side effects. Usually, a small number of healthy volunteers (between 20 and 80) are used in Phase 1 trials.

Phase 2 trials include more participants (about 100-300) who have the disease or condition that the product potentially could treat. Further safety data is gathered and preliminary evidence of the drug’s beneficial effects (efficacy). Research methods for future trials with this drug. If the Phase 2 trials indicate that the drug may be effective–and the risks are considered acceptable the drug moves to Phase 3.

Phase 3 trials include a larger number of people with the disease (approximately 1,000-3,000). This phase further tests the product’s effectiveness, monitors side effects and, in some cases, compares the product’s effects to a standard treatment, if one is already available.  As before, safety data is continuously gathered.  With more participants and the drug being used for longer periods of time, common side effects become more evident.

Phase 4 trials are sometimes conducted after a product is already approved and on the market to find out more about the treatment’s long-term risks, benefits, and optimal use, or to test the product in different populations of people, such as children.

Risks Involved and Informed Consent

Of course, participation in a clinical trial does present some risks.  Adverse reactions and unforeseen side-effects can occur with any treatment which usually stop when the treatment stops.  Sometimes, these risks can be permanent. The risks of being involved in a clinical trial are fully explained before the trial begins.

The FDA has authority over clinical trials for drug, biologic, and medical device products regulated by the agency. Many clinical trials are not subject to FDA regulation but are monitored by the trial institution’s IRB, such as a hospital.  The FDA continually performs inspections of clinical study sites and anyone involved in the research to ensure integrity.

In order to further provide protection to volunteers who participate in clinical trials, the FDA requires that potential participants are given complete information about the study.  This process is referred to as informed consent.  The informed consent process is when the researcher must convey important information about the study; including the risks and benefits of participating, as well as the participant’s rights while enrolled.  The goal of the informed consent process is to protect participants. This informed consent document is reviewed and approved by the human subjects review board for a study before it is given to potential participants. Generally, a person must sign an informed consent document to enroll in a study. 5

When All Is Said and Done…

Clinical trials are an important and necessary part of making medical advances.  Although there are risks involved and they offer no guarantee of success, safety is paramount.  The rules and regulations developed by the FDA are set in place to make the make the patient’s safety a primary goal while allowing new treatments to be developed.

For more information about clinical trials and clinical trial topics you can search the FDA website, as well as other government agencies such as the National Institutes of Health (NIH).  Another important website to find information about clinical trials is ClinicalTrials.gov.  There you can search for information about current clinical trials by disease or condition and find out more information on how to find current studies.

  1. http://www.fda.gov/drugs/developmentapprovalprocess/conductingclinicaltrials/default.htm 

  2. ttp://www.fda.gov/forconsumers/byaudience/forpatientadvocates/hivandaidsactivities/ucm121345.htm#types 

  3. http://www.nih.gov/health/clinicaltrials/basics.htm 

  4. http://www.fda.gov/drugs/resourcesforyou/consumers/ucm143531.htm 

  5. http://clinicaltrials.gov/ct2/help/glossary/informed-consent