What is a clinical trial?

Clinical trials are the means by which we study the effects of a potential new medicine in humans.

There are four phases of clinical trials. All potential new medicines must undergo Phase I – III tests before they are submitted to regulatory authorities for an approval to market. After a medicine is launched, we may then run Phase IV trials to get more information on a specific aspect of the product’s performance. After launch we may also test the efficacy and safety of the drug in new patient populations or in treating different diseases. We may also study new dosage strengths or new formulations. Because these studies are outside the already approved use, they are formally managed as Phase II or III studies.

The 4 Phases of clinical trials

Phase I trials

A new compound is tested in humans for the first time. These are small-scale trials, typically involving less than 100 people. During this stage we look at what the new drug does to the body (pharmacodynamics) and what the body does to the drug (pharmacokinetics). We also assess a range of doses primarily for safety or side effects, but we also in some instances obtain important efficacy information. Participants are mainly healthy volunteers, who are paid for taking part, but can also be patients with the disease the drug will be used in.

Phase II trials

The new compound moves to larger-scale trials involving patients. During this stage, we get more detailed information on the efficacy and safety of various doses in more people and over longer periods of time. We assess whether the compound is effective at treating the target disease and continue to monitor its safety and potential side effects.

Phase III trials

Testing is extended to a larger group of patients. In these studies we may also compare the effectiveness of the new medicine against currently available treatments in order to understand the potential benefits of the new therapy over older therapies, and we continue to assess safety issues and potential side effects. New medicines often undergo several Phase III trials, in different countries, and this may involve several thousand patients.

Phase IV trials

Once a medicine has been approved by regulatory authorities and is on the market, we may conduct further trials to get additional information in the approved indication – for example, to enable us to gather longer-term safety information in a real life setting.

How do you ensure consistent standards between different centres/locations?

All trials have a protocol describing the scientific rationale, objectives, methodology and organisation of the trial. The protocol provides a common template for conducting the study and for data collection and analysis – whether the work is being done in-house or by an external organisation on our behalf. The protocol is used to guide all aspects of the trial activity. Prior to starting a study, the protocol is always reviewed by relevant independent ethics committees and, in most countries, by regulatory authorities as part of the trial approval process.

An independent ethics committee (also known as an institutional review board) is a group of individuals who together are responsible for approving and monitoring clinical research involving humans. Their charge is protecting the rights and welfare of research participants from a scientific, ethical, and regulatory perspective.

A regulatory authority is a public authority, typically a government agency that has autonomous oversight over an area of human activity. A medicines regulatory agency typically has responsibility for ensuring that medicines and medical devices work and are acceptably safe. In most countries the regulatory authority reviews clinical trial protocols and must approve the study before the trial can commence. For example, in the US, the Food and Drug Administration (FDA) must approve the trial design.

As a trial sponsor, AstraZeneca is responsible for initiation, management and financing of the trial, including, for example, selection and training of the researchers, providing study drugs and comparators, continuous data collection analysis and reporting, and ensuring compliance with the protocol.

Why do people choose to take part in clinical trials?

Two types of people participate in clinical trials – healthy volunteers and patients. All potential participants are fully informed about all aspects of the trial and their individual consent is gained before they start. All take part on a voluntary basis.

Patients are not paid to participate in clinical trials, although we generally cover certain expenses they incur from participation in the trial. Patients typically participate because they hope to benefit from the new treatment being tested. They may also wish to contribute to advancing scientific and medical knowledge.

Healthy volunteers are paid for their time and may participate for financial reasons. They may also wish to contribute to advancing scientific and medical knowledge. We work to make sure that the level of compensation provided is consistent with the principle of voluntary participation.

What's next in this section

Selecting a trial location

Our global governance process for determining where we place clinical trials ensures a consistent approach worldwide.

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Protecting participants

In addition to compliance with all relevant laws, we have strict internal procedures for managing safety issues.

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