Welcome to our Early Phase Clinical Unit

(EPCU) in London, United Kingdom.

Level 7 
Northwick Park Hospital
Watford Road
Harrow, Middlesex HA1 3UJ

Participate in a Trial


See what clinical trials we are currently recruiting for.

View Trials

Volunteer Info

Why Participate?

As a participant in a clinical trial, you are making a substantial contribution to finding new and better ways to help other patients in the future.  In addition, some other benefits of volunteering are:

  • You may benefit from a new and better investigational medication which is not currently available to the public.
  • Any medical exams, tests and/or procedures that you receive during the study will be FREE.   
  • You may receive additional attention from healthcare providers involved in the research and your medical care.
  • You may also receive financial compensation for your time and travel.  
  • Free meals and care for the duration of your stay

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About Clinical Trials

The development of an innovative new treatment is often a lengthy and costly process - all treatments will have previously undergone rigorous testing in the laboratory before progressing onto testing in humans.

A clinical trial is the term used to describe the testing of a new treatment or medical device to evaluate whether the drug or device is effective and safe for people to use. Other terms often used to describe clinical trials are drug studies or drug research.

Clinical trials are carried out under the strict supervision of fully qualified doctors, nurses and other health professionals and all trials must first be approved by an Independent Review Board (IRB). IRBs comprise both laypersons and professionals - their main concern is safeguarding the interests of the participants.

All PAREXEL clinical studies are done in accordance with ICH Clinical Practice (GCP) which is an international ethical and scientific quality standard for the conduct of trials. We also follow the regulatory guidelines set by the country that the study is being conducted in.

By volunteering for a PAREXEL clinical research trial, you are not only helping to benefit the wider community through the development of better medicines, you'll also be paid for your time and any inconvenience.

- See more at:


  • What is a clinical trial?
  • Why should I participate in a clinical trial?
  • What are the risks and benefits of participating in a clinical trial?
  • Is it safe?
  • Will I be paid for taking part?
  • How long do the trials last?
  • Can I continue to take my regular medications during the trial?
  • Who will I interact with during the clinical trial?
  • How long do visits last?
  • How often I can take part?
  • What if I have a problem?
  • What if I want to keep taking the medication?
  • What can I expect?
  • What are the important questions to ask about a clinical trial?
  • What happens first?
  • What sort of medicines do you test?

What is a clinical trial?
Before a new treatment is administered to human beings, it is carefully studied in the laboratory and tested in animals in so-called pre-clinical trials. Products with the most promising pre-clinical trial results are moved into clinical trials where the investigational treatment is tested on human volunteers (also called trial or trial participants) under the supervision of a physician (also called an Investigator) and other medical professionals. In a clinical trial, participants receive specific investigational treatments according to the research plan or protocol created by the investigators. These treatments are developed by pharmaceutical, biotech or medical device companies and may be medical products, such as drugs, or devices or procedures. Clinical trials may compare a new investigational treatment to a treatment currently available, to a placebo which contains no active ingredients, or to no intervention at all.  Clinical trials are usually conducted over four phases.  See below for a detailed description of each phase.

At PAREXEL, clinical trials are handled in accordance with International Conference on Harmonization (ICH) Good Clinical Practice (GCP) guidelines that are internationally accepted ethical and scientific quality standards for the conduct of clinical trials

Phase I 
Sometimes referred to as healthy volunteer trials, a Phase I clinical trial often tests an investigational treatment 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 and 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 starting doses of the drug used in Phase I trials are very small and are only increased during the trial if no significant side effects or intolerance is seen.

These trials are an important step in finding new treatments for the future and it is usually for these kind of trials that PAREXEL is looking for healthy volunteers.

Phase II 
Once an investigational treatment has successfully passed the Phase I trial stage, it will be administered to a larger number of people (i.e. usually 100 to 200 patients). In these trials the investigational treatment will be tested in those who are actually suffering from the condition that it is intended to treat. The objective of Phase II trials is to help the manufacturer of the investigational treatment identify the medicines with a genuine therapeutic potential (the drug will actually help to treat the condition that it is being targeted towards).  PAREXEL actively recruits patients with various illnesses to conduct Phase II trials.

Phase III 
Phase III trials are an important turning point for the manufacturers of the new investigational treatment. The purpose of phase III trials is to gather even more information about the effectiveness and safety of the new treatment from large numbers of patients (likely to be several hundred to several thousand patients), comparing its effectiveness with standard treatments. Phase III trials generally run from two to four years and are likely to be carried out in many different research sites – even different countries. 

Phase IV Trials
Phase IV trials are carried out when the investigational treatment has become available on the market either for prescription or is available over the counter. The information gathered from such trials provides the regulatory authorities and the manufacturer of the treatment with valuable information on its properties when administered to different groups of the population, and any side effects that may become apparent with continued use.

Why should I participate in a clinical trial?
There are various reasons why you may volunteer to participate in a clinical trial. You may be suffering from a disease for which a good treatment does not currently exist. You may want to contribute to the discovery of new treatments that may one day relieve or eliminate an illness.  Whatever your reason, during a clinical trial you will receive personal and specialized medical attention from our physicians and clinical staff, as well as free medical tests and trial medication. You may also receive compensation for your time.

What are the risks and benefits of clinical trials?
Potential risks and benefits vary from trial to trial. However, if you are interested in volunteering for a specific trial potential risks and benefits will be explained to you before you give your consent to participate. You will also be able to ask questions of our clinical staff if you have any concerns that are not addressed.

Is it safe?
Before any participant can take part in a clinical trial, we take great care to ensure that you are suitable to do so. Participants are required to undergo a thorough medical examination which includes taking blood samples for a variety of tests (including Hepatitis and HIV) as well as performing a tracing of your heart (ECG) and blood pressure. Clinical trials are carried out under the strict supervision of qualified doctors, nurses and other health professionals. All our trial protocols are reviewed and approved by the Independent Review Board and/or the regulatory authority for the country where the trial is conducted.

Will I be paid for taking part? 
By participating in a Phase I (healthy volunteers) trial, it is not anticipated that you will receive any therapeutic benefit and it is therefore, considered ethical and apt that you should be paid for your time and inconvenience.  All payments we make for trial participation will have been approved by an Independent Review Board. The method and frequency of payment will be described in detail in the Informed Consent Form.

How long do the trials last? 
Each trial varies in length. You may for instance, be required to reside in the unit for anything from 3 nights to 3 weeks. However, for the majority of trials we carry out it will be necessary for you to visit the unit on several occasions over a period of weeks, each stay lasting between 48 and 60 hours.

Can I continue to take my regular medications during the trial?
If you are currently taking any medications you will need to provide the names to our medical team so that they can determine if there is any potential risk of a negative interaction. They will let you know if it is safe for you to continue with your medication.   In some cases, you may be excluded from participating in a trial as a result of the medications that you are currently taking.

What happens first?
If you want to be considered for a particular trial you would make an appointment to come to one of our units. You will be given the information about PAREXEL and the upcoming clinical trial as soon as you arrive.

Having read the information about the trial, one of the doctors will take you through the background and purpose of the trial giving you a chance to ask any questions you like. We sometimes do this in small groups and find this approach allows you to get the best understanding of what the trial is all about.

Before anything else happens you must sign an Informed Consent Form, which is a document that outlines the key facts about the trial including all potential risks. Once you have done this we will make some measurements (typically height, weight, blood pressure, ECG - a totally painless recording of your heart's electrical activity - and anything else that is required by the specific trial protocol). You will be examined by the doctor and have a chance to discuss the trial with him or her in private. Blood samples (equivalent to a few teaspoons of blood) will be taken through a needle in the arm and we will ask you to provide a urine sample that we will test for recreational and other drugs. Usually that's about it for what we refer to as the 'screening' phase of the trial. This usually takes place up to three weeks before the trial itself starts.

It will take a few days before the results of your tests come back. If everything is OK you may be offered a place on the trial. Occasionally we may need to repeat some of the tests and you will be asked to come into the Unit so that we can do this.

The staff will confirm the dates of the trial with you and give you details of what you will need to bring with you for your stay. Remember - at any time you may exert your right to withdraw your consent to take part.

What sort of medicines do you test? 
PAREXEL conducts trials in a wide range of therapeutic areas. Some of the investigational treatments 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. We have conducted trials with a wide range of treatments including those for:

  • Many different types of cancers (breast, lung, prostate, etc.)
  • Cardiovascular disease (problems with the heart or circulation)
  • Respiratory disease (diseases of the lungs – such as asthma and emphysema)
  • Disorders of the central nervous system (such as epilepsy, depression, Alzheimers Disease and Parkinson’s Disease)
  • Pain
  • Gastrointestinal disease (disorders of the stomach, gut or bowels)
  • Metabolic disorders (including conditions such as diabetes and osteoporosis)
  • Infectious diseases (e.g. antibiotics for organisms resistant to current treatments – such as HIV, hepatitis )
  • Skin diseases
  • Rheumatoid and osteo-arthritis
  • Liver disease


Who will I interact with during the clinical trial?
You will receive personal attention from our board-certified physicians (also called investigators), as well as nurses, or trained clinical research associates.

How long do visits last?
This will also vary depending on the clinical trial. Most visits for any trial at our units are at least 30 minutes and some may be a few hours. The initial visit will be longer because it will be necessary to assess your history and discuss the consent.

How often I can take part? 
For your health and safety it is important that you do not take part in trials too often and especially not simultaneously (i.e. enroll to take part in trials with us and at other centers). If you have taken part in a clinical trial and you are unsure about when you can safely participate in another one, we are always more than happy to discuss this with you.

What if I have a problem?
If you have any questions or problems, during unit hours you can call our contact numbers and a research associate or staff physician will be able to assist you. After unit hours, you will reach the answering service that will be able to page an appropriate person to address your concerns. Our physicians and professional staff are available 24 hours a day, 7 days a week.

What if I want to keep taking the medication?
Because most of the medications we trial are investigational and have not yet been approved for general release to the public, continuing the medication after your clinical research participation ends may not be an option. This is determined on a trial by trial basis. We will provide you with appropriate referrals for treatment at the end of your trial participation.

What can you expect?
Once you have enrolled in a trial, you may receive a physical examination. Your trial physician or a research staff member will review your medical history as well. A detailed description of your specific clinical trial and what's expected of you will be outlined in your Informed Consent Form.  

What are the important questions to ask about a clinical trial?

  • What is the purpose of the trial?
  • What does the trial involve?
  • What type of tests will need to be done for the trial?
  • How many trial visits are required?
  • How will participating in the trial affect my daily life?
  • Can I continue to take my regular medications during the trial?
  • What is likely to happen in my case with, or without, this new experimental medication?
  • What other choices do I have?
  • What are the advantages and disadvantages?
  • What side effects are possible from this trial treatment?
  • Will I receive a Placebo (Blank)?


An unexpected or undesirable symptom or illness which occurs during a study

A commercial organization that conducts all or some of the activities involved in the drug or product development process. PAREXEL is one of the largest CROs in the world.

A trial or study in which neither the research participants nor the study staff know which participants are receiving the study drug or placebo.

The EMA is responsible for the scientific evaluation of medicines developed by pharmaceutical companies for use in the European Union.

The FDA is a United States government agency with the power to authorize approval for new drugs.

The IRB is a panel of experts and lay people representing a cross-section of society who are independent of the company and who have the responsibility of reviewing and approving all study protocols.

A document that outlines the key facts about the trial including information on the potential risk associated with participating in the study and all available data on the drug being tested. Key information which must be included in an ICF include:

• Why the research is being carried out
• What will be done during the trial and for how long
• What risks are involved in the trial
• What the researchers want to achieve by carrying out the trial
• The fact that participants have the right to leave the trial at any time

The study of absorption, distribution, metabolism and excretion of drugs from the body.

The study of drug action on the physiology of the body

An inactive pill, liquid or powder that has no treatment value. In a placebo controlled trial, the study will be comparing the new drug against the placebo.

The doctor responsible for the performance of the trial and for the integrity, health and welfare of the participants during the trial. The PI must be a qualified doctor or dentist and someone who is trained and experienced in research.

A formal written document that provides details about how a trial will be conducted. All study protocols must be reviewed and approved the Independent Review Board.

A scientific method in which the participants or patients are assigned to investigational drug, comparator drug or placebo.

An individual, company, institution or organization which takes the responsibility for the initiation, management and/or financing of a trial - generally the manufacturer.

A key member of the study team, study coordinators are often trained nurses. The study coordinator's name and contact telephone numbers are included in the study ICFs in order that participants may contact them if they have any queries about the study.