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Clinical trials

Clinical trials are an essential step in the development of new medicines.

We are working on treatments for a number of pressing medical challenges that include infectious diseases, heart disease, stroke, cancer, inflammatory diseases like rheumatoid arthritis and nervous system disorders, such as Alzheimer’s disease.

Before a new medicine can be tested in humans, we produce comprehensive documents, combining all findings from laboratory and animal studies, to demonstrate to regulators that the potential benefits of the medicine outweigh the risks.

Clinical trials of new Pfizer medicines take place all over the world and are conducted in accordance with recognised international standards, as well as local laws and regulations. In 2012, Pfizer processed more than 37,000,000 data points from our clinical trials.

There are three stages of clinical trials that lead up to the approval of a new medicine:

Phase I

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

Phase II

The drug’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 drug 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 new medicine or a control group receiving a placebo (a dummy medicine).

Phase III

Tests are expanded to include a much larger population; from a few hundred to thousands of volunteer patients. This is also usually carried out on a randomised control basis. Throughout this testing process, multiple safeguards are in place to protect the rights and safety of study participants.

Every trial we run involving our compounds is registered and made public. 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

Through these efforts we hope to develop new medicines and benefit those most in need.