Skip to main content
The William Harvey Research Institute - Faculty of Medicine and Dentistry

Frequently Asked Questions (FAQs)

What do the different phases of clinical trials mean?


Phase I clinical trial researchers are often testing a treatment which may be in the earliest stages of development in a small group of healthy people (i.e. usually 10 to 30 volunteers). The information gathered from such trials will provide the manufacturers with important data on how the medicine is tolerated, how the body absorbs, breaks down and eliminates the drug and whether any side effects have been experienced by those taking part in the trial. The initial doses of the drug used in Phase I studies are very small and are only increased during the study if no significant side effects or intolerance is seen. We rarely do Phase 1 trials.

Once a new medicine has successfully passed the Phase I study stage, the drug will be administered to a larger number of people (i.e. usually 100 to 200 patients). In these trials the drug will be tested on those who are actually suffering from the condition the medicine is intended to treat. The objective of Phase II studies is to help the manufacturer of the medicine to identify a drug with a genuine therapeutic potential (it will actually help to treat the condition being targeted).

Phase III trials are an important turning point for the manufacturers of the new medicine. The purpose of phase III trials is to gather even more information about the effectiveness and safety of the new medicine from large numbers of patients (several hundred to several thousand patients). It will improve the medicine’s effectiveness with standard treatments. Phase III studies generally run from two to four years and are likely to be carried out in many different centres – and often different countries.

Phase IV trials are carried out when the medicine has become available on the market for prescription or is available over the counter. Information gathered provides the regulatory authorities and the pharmaceutical company with valuable information on the drug’s properties when administered to different groups of the population. Also of any side effects that may become apparent with continued use.

By participating in a Phase I (healthy volunteer) study, it is not anticipated that you will receive any therapeutic (treatment) benefit from taking part. It is therefore considered ethical and appropriate that you should be paid for your time and inconvenience. The amount of payment you receive for each trial will vary and is calculated on the amount of time that you have to devote to the study, the number of visits and also the inconvenience anticipated based on the planned procedures. An Independent Research Ethics Committee will have approved all payments to volunteers for trial participation.

Clinical trials are carried out under the strict supervision of fully qualified doctors, nurses and other health professionals. All trials are run in accordance with European legislation and two government bodies must first approve all trials before any clinical procedures may commence. These are the MHRA (Medicines and Healthcare Products Regulatory Agency) and a government authorised REC (Research Ethics Committee). In order to give approval for the study to go ahead the MHRA experts will assess all applications for new medicines to ensure that they meet the required standards. Members of a REC will often include patients, members of the public, nurses, GPs, hospital doctors, statisticians, pharmacists and academics, as well as people with specific ethical expertise gained through a legal, philosophical or theological background.

Before every trial volunteers are given a full pack of information about the study to read through in detail and are able to spend as much time as required with one of the Research Doctors discussing all the details and potential risks of the study. This process is called informed consent and will be completed before any study procedures are able to take place. After the formal consenting session with the doctor you will be able to take the information home to discuss with friends, family and your GP. A consent form should not be signed until the participant feels that they have enough information to make the decision to take part, and even once the form is signed volunteers are able to withdraw their consent from a study at any time.

Before any volunteer can take part in a clinical trial, we take great care to ensure that you are suitable to do so. Volunteers are very carefully screened against the approved study protocol and are required to undergo a thorough medical examination, which includes taking blood samples for a variety of tests as well as tracing your heart (ECG) and measuring your blood pressure. We will also contact your GP to check that there are no medical conditions in your history that might affect your participation. Only those volunteers meeting the strict criteria set will be selected for participation and included in the study. They are very closely monitored throughout for any potential side effects.

If you want to be considered you will be information about the trial and given as much time as you need to read through it. Next you would make an appointment to come to the Unit and you will be asked to bring Identification with you and your GP contact details. A doctor will take you through the background and purpose of the study giving you a chance to ask any questions you like. Once you feel you have enough information to decide to take part the screening medical will commence. The screening visit will usually include having your heart traced (ECG), your blood pressure measured, and the screening blood samples taken. You will have urine tests which will include a drug screen. During the screening a doctor will conduct a medical examination and you will be asked about your medical history and any medication that you may have used.

With your permission, we will contact your GP surgery to check that there is no history of a medical condition, which may affect your participation in the study. We will ask your GP to confirm any medication that you have used.

We conduct trials in a wide range of medical conditions. Some of the medicines are newly discovered and may eventually lead to breakthroughs in disease management and patient care. Other trials involve medicines that have been marketed for many years, but the manufacturer may want to develop an improved formulation or a try out a new delivery system. Some of the areas where we have conducted trials include:

  • Cardiovascular disease (problems with the heart or circulation)
  • Respiratory disease (diseases of the lungs – such as asthma)
  • Disorders of the central nervous system (such as epilepsy, depression) & treatments for pain
  • Metabolic disorders (including conditions such as diabetes)

For your health and safety it is important that you do not take part in trials too often and especially not simultaneously i.e. enrol to take part in studies with us and at other centres. If you have taken part in a clinical trial and you are unsure about when you can next safely participate in another one, we would be happy to discuss this with you.

Mostly studies are ‘out-patient’ based which means that you would have to attend for several visits to the unit for monitoring during the trial. Occasionally a trial may be required to be resident in the unit.

Part of our study recruitment processes involve contacting your family doctor, with your permission. This is to ensure that all volunteers who take part in a study are eligible to do so.

Queen Mary, University of London and Barts and the London School of Medicine and Dentistry are registered under the Data Protection Act 1998. We have a responsibility to ensure that we comply with the principles of data protection. With your consent, we will store information about you on our secure volunteer database, which is only accessible by relevant members of staff. If you choose to participate in a study then you will be asked to give your consent for your information to be shared with relevant personnel from the company sponsoring the trial and their representatives. Volunteer records may also be disclosed to regulatory authorities for medicines in the UK and elsewhere. Our volunteers are entitled to access information held about them if they so wish.

Back to top