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Clinical trials

Only about 250 of the original 10,000 compounds will make it through to pre-clinical testing. Of those 250, five will make it to first-in-human studies. The rest will be screened out during the pre-clinical tests – for example, through computer simulation (in silico), in the laboratory in test tubes (in vitro) and through testing in other living organisms, most of which are rodents.

The subject of animal welfare is very important and we take our responsibilities in this area extremely seriously. All research involving animals carried out by Pfizer is conducted in accordance with our policy on laboratory care and use of animals. This policy is based on the ‘3Rs’: the replacement of animals with alternatives wherever possible; the reduction of the number of animals used; and the refinement of procedures. At Pfizer, we have added two additional ‘Rs’ as important additional principles that apply to our work: respect for animals, and recognition of the important contribution that animal-based research makes to our goal of improving human and animal health worldwide. We also meet or exceed all relevant national legislation. In the UK, experiments involving animals are strictly regulated by the Animals (Scientific Procedures) Act 1986 and veterinary advice and care is available at all times. Every place, every project and every person involved in animal research must get a licence from the Home Office before the experiment can begin. Every application for a licence must explain why the animal research is vital to medical progress and why alternatives to the use of animals are not possible. The application must also specify that the research has not been done before anywhere else.

Regulatory authorities for all new prescription medicines require information from animal studies. Animal use remains necessary, as it is only possible to answer certain questions about a medicine’s safety and effectiveness by observing it in an entire body. Everyone looks forward to a time when it will no longer be necessary to involve animals in research. However, with present knowledge as it is, there is no alternative if cures or improved treatments are to be found.

We are working on cures and treatments for 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. Research involving animals also makes a significant contribution to veterinary care for both farm and companion animals.

Before a new medicine can be tested in humans, Pfizer produces comprehensive documents, combining all findings from laboratory and animal studies, to demonstrate to regulators that there is no evidence that the medicine poses a significant risk to humans. Human trials of Pfizer medicines don’t just take place in one country, and they are often run in different countries at the same time. No matter where they take place, Pfizer clinical trials are conducted in accordance with recognised international standards, as well as local laws and regulations. All clinical trials carried out by Pfizer are always relevant to the health needs of that country.

Our main concern in all clinical trials is patient safety. There are three stages of clinical trials that lead up to the approval of a new medicine and if there are any safety concerns the trial can be stopped at any time.

This 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.

Next, 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 are carried out on a randomised basis, meaning that part of the group will receive the new medicine and the rest will receive a placebo (a dummy medicine). In cases where there is already an alternative standard treatment, a third group will usually be given that medication. Often, these trials are ‘double-blind’, which means that neither the patient nor the researcher knows which medication a patient is taking in order to ensure robust results.

At this stage, 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, double-blind 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 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 online at The results of all Pfizer initiated clinical trials are also online. You can view these at