People count on us to make medicines that have well documented safety and effectiveness profiles and offer value. Clinical trials (also known as clinical studies) are a critical step in this process.

At any one time, we are conducting approximately 100 clinical trials in the UK. On average, around 5,000 people are participating in these trials each year.

These volunteers are playing a vital role in the rigorous and systematic testing process medicine must undergo before receiving approval for us. This process is designed to evaluate whether a new product should be approved for use in the broader population.

Our clinical trials are designed, conducted and monitored in adherence to the same standards, whether they take place in the UK or elsewhere around the world. In conducting clinical trials, we also adhere to the guidelines of The International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use.

Clinical Trial Transparency

Regardless of their outcome, we register clinical trials at We have been posting results of clinical trials at the site since October 2008.

The ABPI Code of Practice requires that companies in the UK register current and future trials within 21 days of enrolling the first patient, and results must be published within one year of marketing authorisation or one year from completion for marketed products. We are pleased to be meeting these requirements.

Upon request, we also evaluate requests for access to clinical trial data from external researchers. Each request is evaluated based on criteria that balance the need to advance science with the need to protect intellectual property and confidential information (and in compliance with applicable privacy and data-protection laws, rules and regulations).

We provide clinical study protocols to biomedical journals when submitting a manuscript on a clinical trial, allowing journal editors and peer reviewers to use this protocol in their evaluation of the manuscript for publication (and, key sections of protocol may be published upon acceptance).

Clinical Trial Phases

Each clinical trial is designed to answer certain research questions. They follow strict, predefined protocols to ensure safe and accurate results. Each phase has a different purpose in the development of a medicine or vaccine:


Researchers test an experimental drug or treatment in a small group of healthy people (20-80) for the first time to evaluate its safety, determine an appropriate dosage, trace what happens to the compound in the body, and begin to identify side effects.


The drug or treatment being studied is given to a larger group of people with the disease (100-300) to obtain preliminary evidence of an effect and to further evaluate its safety. If there is evidence of an effect and the risks are considered acceptable, the drug may move to the next stage.


This phase of trial tests a drug candidate in a larger number of people with the disease (1,000-3,000) further testing its effectiveness and monitoring for side effects. In some cases this will be compared to a treatment standard, if one is already available.


After a drug or treatment has been approved by the appropriate government and regulatory agencies and is being marketed, we may study its safety and effectiveness over a longer period of time and in a larger number of people. We may also continue to study some of our marketed products for new indications. Thousands of people usually participate in Phase IV trials.

Please click here for the ABPI's infographic - 'Inside Innovation: the medicine development process'