Clinical Study FAQs

What is a clinical trial?

Before a new treatment can be prescribed to a patient, it goes through quite the journey. It starts in the lab, with so-called pre-clinical trials during which scientists carefully study the potential new drug. If the results of these pre-studies are promising, the investigational drug begins the clinical trial process where its effects are studied in people. These volunteers (sometimes called participants or patients) may receive specific study treatments, a placebo, or no study treatment at all, and complete various assessments and study clinic visits.

Each clinical trial follows a carefully-designed research plan called a protocol, which has been approved by groups of medical professionals and specialists to protect participants’ safety and health. All clinical trials we run with our partners meet international standards and guidelines.

Clinical trials are usually conducted over four phases.

Phase I

This is the first time an investigational drug will be tested in people, and often involves a small group of healthy volunteers – about 10 to 30 people. Here, we are trying to understand how the potential medicine interacts with the body and if there are any side effects. The starting doses are very small and are only increased if there are no side effects. 

Phase II

Phase II clinical trials aim to understand how safe and potentially effective an investigational drug is for people with the condition it hopes to treat. This phase often compares the investigational drug to a placebo and usually involves between 100 and 200 participants. These trials help us understand if the investigational treatment has any effect on the condition itself.

Phase III

In Phase III clinical trials, the potential treatment is monitored in even more volunteers, likely several hundred or even several thousand. This is an important step in the development of a potential medicine because its aim is to gather more information about the effectiveness and safety, and how it compares to already-approved treatments. This phase can run for several years and might take place at many research sites around the world.

Phase IV Trials

Once a potential treatment has worked its way through Phases I, II, and III and has been successfully approved, by regulatory authorities it’s available to the public. Phase IV trials take place in the “real world” rather than at a clinical study site, and researches any long-term effects the treatment may have.

Why should I participate in a clinical trial?

Deciding to take part in a clinical trial is a deeply personal decision for you and your family. Many volunteers take part to find potential new treatments for a specific condition. Others do it to help advance modern medicine for people in the future. Whatever your reason, your health and safety are always the top priority.  

You may benefit from new or better investigational medication not currently available to the public, although this cannot be guaranteed. However, any study-related care will be provided at no cost. You might also be compensated for your time and travel.

What are the risks and benefits of clinical trials?

The risks and benefits vary from trial to trial. Before you participate, all the risks we know about will be explained in an informed consent form you must read and sign before you take part. You may benefit from the investigational treatment, although we can’t guarantee this. Along the way, our clinical staff will be there to address any concerns and questions you may have.

Is it safe?

Before you ever begin a clinical trial, volunteers go through certain medical exams during a “screening period” to make sure you’re healthy enough to take part. During the trial itself, doctors, nurses, and other healthcare professionals will carefully monitor any changes in your health. If you experience any side effects you can’t tolerate, or if your condition worsens, you may be taken off the study for your safety. All trials and the exams we run in them are reviewed and approved by the Independent Review Board and regulatory authorities in every country the trial takes place.

Will I be paid for taking part?

If you take part in a Phase I clinical trial (where an investigational treatment is tested in healthy volunteers), you probably won’t experience any therapeutic benefits. Because of that, you’ll be compensated for your time and inconvenience. The way these payments will be made will vary depending on your trial, but will be described in full in the Informed Consent Form.  

How long do the trials last?

Each trial is different, so your involvement will vary based on the trial’s pre-determined plan, or protocol. For some, you may need to stay in a study clinic for a few nights. For other trials, you may simply need to visit a study clinic every couple of weeks. Before you begin, all time requirements will be explained to you.

Can I continue to take my regular medications during the trial?

It depends on the trial. You will need to tell you study team about all medicines you are currently taking so they can decide if there is any potential risk of a negative interaction. They will let you know if you can continue on your current medication or if the trial may not be a good fit for you because of it.

What happens if I want to join?

If you’re interested in taking part in a particular trial, you would make an appointment to visit one of our study clinics. Here, we’ll give you more information on the trial and talk you through the background and purpose of this research. Sometimes this happens in small groups and other times it’s a one-on-one conversation. Either way, your study doctor will answer any questions you might have.

At this point, if you’re still interested, you would carefully read and sign an Informed Consent Form. This document outlines everything that will happen in the trial, along with the potential risks and benefits. After this, you will be examined by a doctor to make sure you are healthy enough and meet other requirements to participate. This assessment can include basic measurements like height and weight, blood tests, urine samples, and other tests we might need to understand if you’d be a good fit. This is called the “Screening Period” and usually takes place a few weeks before the “Dosing Period” begins.

It may take a few weeks for your test results to come back, and sometimes we may need to repeat some assessments. Your study team will use these to decide if the clinical trial would be a good fit for you. If you qualify, you would be offered a place on the trial.

What types of medicines do you test?

Over the years, Parexel® has helped develop new or improved medicines for a range of conditions. We have deep understanding of the following areas:

  • Many types of cancer (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, Alzheimer’s 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 (such as HIV and hepatitis)
  • Skin diseases
  • Rheumatoid and osteoarthritis
  • Liver disease


    Who will I interact with during the clinical trial?

    You will have a team of medical professionals dedicated to your care throughout your time on the trial. This includes board-certified physicians (also called investigators), as well as nurses and trained researchers.

    How long do visits last?

    The length of your visits depends on your particular trail. Most clinic visits are at least 30 minutes and can last up to a few hours. Your first visit will likely be longer as we collect information about your medical history and discuss the clinical trial with you. Your study team will let you know what to expect at each visit.

    What if I have a problem?

    Please know that if you decide to take part, you will be supported 24/7 throughout your time in the trial. During business hours, you can call your clinic and a research associate or staff physician will help you. After hours, you will reach an answering service which will alert the appropriate person to contact you.

    What if I want to keep taking the medication?

    Because most of the potential drugs we are studying have not been approved for public use, continuing on the investigational drug after your trial ends might not be an option. However, this is decided on a trial-by-trial basis. Even if you can’t continue on your investigational drug, we can provide you with appropriate referrals for treatment at the end of the trial.

We are always available for a conversation.

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