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Clinical Trials

Clinical trials are an essential step in the medicine development process.


We are currently conducting clinical trials for a number of medical conditions including infectious diseases, cancer, inflammatory diseases and central nervous system disorders.

Before a medicine can be tested in humans, we produce comprehensive reports, combining all findings from laboratory and animal studies, to demonstrate to regulatory agencies such as the European Medicines Agency that the potential benefits of the medicine outweigh the risks.

Clinical trials of Pfizer medicines take place all over the world and are conducted in accordance with recognised international standards, as well as local laws and regulations.


Pfizer clinical Trials Performed in the UK during 2017

During 2017 within the UK, 60 Pfizer clinical trial protocols were in place, across 288 clinical trials sites that to date have enrolled over 4,000 patients.1


As part of our INSPIRE programme (Investigator Networks, Site Partnerships and Infrastructure for Research Excellence) we have built a trusted network of preferred locations for clinical trial research, which now spans over 90 sites around the globe, with 5 located in the UK.


There are 3 main stages of clinical trials that lead to the approval of a medicine


Phase I: 20 – 100 healthy volunteers2

The first study is usually carried out on a small number of healthy volunteers (between 20 and 100), who take the medicine for a short period of time whilst being closely monitored. Tests are carried out to see exactly how the medicine is acting in the body.

Phase II: 100 – 500 patients with the disease2

The medicine’s effectiveness and minimum and maximum doses must be established, so testing is usually carried out on another small group of people who suffer from the disease or whose condition the medicine is designed to treat. Normally several hundred patients are involved in this round of testing. Most phase II trials randomly assign patients to either the medicine or a control group receiving a placebo (a dummy medicine).

Phase III: 1,000 – 5,000 patients2

Trials are expanded to include larger populations, typically between 1,000 – 5,000 patients, and are usually carried out on a randomised control basis. This means each participant is randomly assigned to either the medicine or a control group receiving a placebo (dummy medicine) – based on chance, rather than decided by the doctor or participant. Randomised control trials enable researchers to put any differences in outcomes between the groups to the treatment received.³

Throughout the trials process, multiple safeguards are in place to protect the rights and safety of study participants.


Transparency of clinical data

In line with regulatory requirements, every trial we run involving our compounds is registered and made public. In keeping with mandatory requirements, we are committed to transparency, and so publish information about the purpose of each trial, the eligibility of patients to join the trial and the location of the study.

You can see this information at 



  1. Pfizer data on file. July 2018.
  2. ABPI, May 2014, 'Innovation in Medicine Infographic'
  3. NICE, 'The NICE Glossary'


PP-PFE-GBR-1163 / July 2018