About Clinical Trials

What is a clinical trial?

A clinical trial is a scientific study in people that helps to determine if and how a drug or therapy works. These can also be called clinical studies, or clinical research. Clinical research helps us answer specific questions about an investigational drug (The drug being studied.) , such as:

  • Is it effective?
  • Is it more effective than another established treatment?
  • Is it safe and/or what are its side effects?

The development of a new medicine can take more than 10 years. Although long, this length of time is vital to ensure each medicine is tested rigorously.

With each phase of clinical trials, our knowledge about a medicine and its safety and effectiveness grows.

Phase 1 Is it safe? Months
Phase 2 Does it Have
Side Effects?
Up to two Years
Phase 3 How Well
Does it Work?
One to four years
Phase 4 How Else
Could it Work?
More than a year

Planting the seed

In Phase 1 trials, researchers test a new drug or treatment in a small group of people (20-80) for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.

Laying down roots

In Phase 2 trials, the study drug or treatment is given to a larger group of people (100-300) to see if it is effective and to further evaluate its safety.

Preparing for harvest

In Phase 3 trials, the study drug or treatment is given to large groups of people (1,000-3,000) to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.

Expanding the yield

In Phase 4 trials, studies look at real-world experience over a long time and provide additional information on the drug’s risks, benefits, and optimal use.

Adapted from CISCRP

Who is involved in clinical trials?

The Sponsor

They initiate the trial

They initiate the trial

Can be doctors, hospitals, pharmaceutical companies and more.

The Site

Where the trial happens

Where the trial happens

Can be a clinic, hospital, academic institution, or doctor's office.

The Principal Investigator

The doctor or researcher

The doctor or researcher

The person responsible for conducting the trial.

The Study Coordinator

The research assistant

The research assistant

Supports the Investigator to carry out the study.

The Participant

You! Or your family member

You! Or your family member

Could also be called the "patient," "volunteer," or "study subject."

Ethics Review Boards

They protect you

They protect you

Review the study, ensuring it is ethical and fair.


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