About clinical studies1

People volunteer for clinical studies to help researchers learn about new and existing treatments. Carefully conducted clinical studies—led by medical doctors called principal investigators—are the optimal way to find new treatments.

Clinical studies are conducted at approved study sites such as hospitals, universities, doctors’ offices, and community clinics.

The following terms are commonplace in clinical studies. You may want to familiarize yourself with them to properly understand how they work.


Each clinical study has a plan, called a protocol, which must be conducted according to strict scientific and ethical principles.

Details include participation criteria (also called inclusion criteria), test schedules, procedures, medications, and study length.

Placebo/sugar pill

Sometimes, a drug undergoing investigation is compared against a placebo, also called a sugar pill.

The placebo looks like the study drug, but contains no active ingredients. Using a placebo helps increase the possibility that any effects seen in the study are due only to the study drug itself.

Inclusion and exclusion criteria

Inclusion criteria are the factors that allow someone to participate in the study. Exclusion criteria are factors that prohibit someone from participating in a study.

These criteria are part of the study protocol, and help to set parameters for study outcomes.

FDA approval process1

The development of potential treatments is divided into steps called “phases.” Generally, the study treatment must pass through each phase successfully before it can continue on to the next.

Phase 1 Phase 2 Phase 3
Usually healthy volunteers (although may include people with the disease) People with the disease People with the disease
Safety and how the body breaks down
the study treatment
Safety and effectiveness (the ability of a study treatment to produce a beneficial change)
Long-term safety and effectiveness compared to current standard of care or a placebo (a sugar pill)

Once the studies are complete, the study results along with other information on the drug are submitted to and reviewed by a government agency (eg, in the United States, the Food and Drug Administration, or FDA). If the data show the study treatment is safe and effective, it may be approved for use by prescription.2

Consider participating1

Taking part in a clinical study is voluntary. That means you don’t have to join if you don’t want to and that your future health care options will not be affected if you decide that you don’t want to participate.

You can even withdraw your consent to participate in a study once you’ve joined if you change your mind.

Understanding your rights: informed consent
If you want to take part in a clinical study, you’ll be asked to review an informed consent form (ICF).

Among other information, an ICF will tell you:

  • What to expect during your time on the study
  • What tests you’ll have
  • The potential risks or benefits of the study drug
  • Your rights as a study participant

You can review the ICF information with a member of the team at the study site—they’ll answer any questions that you might have. You may also ask your doctor or a friend or family member to review the ICF.

Once your questions have been answered, you’ll be asked to sign the ICF. This shows that you understand the study’s requirements and agree to take part.

You can still leave a study at any time if you change your mind, even after signing the ICF.

Potential benefits1

  • Receiving regular, close monitoring and care from an experienced research team
  • Helping others by contributing to medical research
  • Gaining access to investigational treatments
  • Playing an active role in your own health care

Risks and disadvantages1

  • Unpleasant, serious, or even life-threatening adverse effects of the treatments being tested
  • Time commitments for study participation
  • The treatment being studied may not work
Ultragenyx Clinical studies in FAOD

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References: 1. Learn about clinical studies. National Institutes of Health Clinical Center. https://clinicaltrials.gov/ct2/about-studies/learn. Updated December 2015. Accessed August 17, 2016. 2. Development & approval process (drugs). U.S. Food and Drug Administration. http://www.fda.gov/Drugs/DevelopmentApprovalProcess/. Updated January 2016. Accessed August 17, 2016.