What are clinical trials?

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A clinical trial is a scientifically constructed investigation of a treatment (e.g. medication) that involves patient volunteers. Some clinical trials involve a mixture of healthy people and patients in the study group. Clinical trials are the final stage of medication (drug) research in the treatment of many diseases. They may also be conducted on new procedures (e.g. imaging scans). Clinical trials test new approaches to preventing disease, new techniques of screening for early detection of diseases (e.g. cancers), new tests to diagnose known diseases, new treatments (e.g. drugs), genetic studies, and also new approaches to managing end-of-life care for terminally ill patients. For many patients, clinical trials are an important step in accessing newly discovered therapies before they become generally available. It is important to be well informed about the risks and benefits of any treatment before starting.

Why are clinical trials important?

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Clinical trials are used throughout medicine to improve treatments available to patients. Scientists use laboratory and animal studies to help them to understand diseases and develop new treatment ideas. But for a new drug to be used routinely in people, the effect of new or different treatments on patients and healthy persons must be known. Clinical trials are also needed to determine the correct dose of a new medication, to determine whether the drug will treat the disease effectively in humans, the safety of a new drug alone and in combination with other therapies, and to determine whether a new treatment is better than standard treatment. Clinical trials are one requirement for a new drug to become licensed by the Therapeutic Goods Administration (TGA) in Australia. Without registration, a treatment cannot be provided under the Medicare health scheme.

What are the benefits of being involved with a clinical trial?

Clinical trials allow access to new medications and treatments before they would otherwise be widely available. If the drug is effective, those enrolled in trials will be among the first to benefit. Being a participant in a clinical trial also improves the understanding and knowledge of many conditions, and has the potential to benefit future suffers of your disease. When you are an enrolled participant in a clinical trial, your health care is provided by a leading physician in that field (e.g. a consultant or an experienced, senior registrar). This allows close monitoring of any side effects of the treatment, limits any potential problems, and allows early recognition of problems. It also ensures that you receive the best available care and monitoring while you are involved. There is some evidence that suggests cancer patients who are involved in clinical trials have a better outcome than those who are not.

What are the disadvantages of being involved with a clinical trial?

A clinical trial will involve new medications or treatments for which not all the side effects and risks are known. The doctors may not be able to predict all the side effects that may occur. Sometimes the effectiveness of a new treatment will not be fully known until there are clinical trials. For this reason, new drugs may not always work, or they may be less effective than the current standard treatment. Patients must also consider that this treatment may work for some people, but not necessarily for them. Research also continues to determine why some treatments work in some people and not in others.

What research happens before a clinical trial?

There are a number of stages of development that occur before a medication is trialled in humans (clinical trial). Early steps in drug development occur in a laboratory where individual cells can be examined under a microscope and the effects of the medication can be monitored. If a medication is thought to have the desired effects, it may then be tested on animals. If there are little or no adverse effects and the medication is shown to be effective, then drug companies can apply for testing in humans. Human testing is the final stage in the drug’s development. A drug will only reached this stage if it has shown promising results in laboratory and animal studies, and there are no known serious side effects for humans.

What are the different types of clinical trials?

Clinical trials in humans are divided into 4 phases.
Phase I trials: The first part of development. The aim of this trial is to determine if the treatment is safe, what the expected side effects are, and to determine a dose for the treatment. These are usually only conducted with a small number of healthy volunteers. The trials usually last a few weeks to months.

Phase II trials: The aim of these trials is to establish how well a treatment works. These trials are usually conducted with a small number of supervised patients. Specialists in the field of the disease will monitor the patients and review their progress regularly.

Phase III trials: These trials involve a larger number of patients. Their aim is to show whether or not a new treatment is better than the current standard treatment. The trial involves 2 groups: one group of patients will get the standard treatment, and the other group will get the newer treatment. It is usual for the patient and the doctor not to know which of these treatments the patient is receiving. Because the trials involve a larger number of patients, this study also gives a better understanding of the potential side effects of the new treatment.

Phase IV trials: Continued research undertaken after the treatment is marketed and introduced as part of standard therapy. The aim of these trials is long-term surveillance of the treatment. Many thousands of patients are usually enrolled in phase IV trials.


  1. United States National Institute of Health Services (cited December 9th 2007) Understanding Clinical Trials [Available online: http://www.clinicaltrials.gov/ct2/info/understand] (last updated 20th September 2007)
  2. Medicines Australia (cited November 31st, 2007) Clinical Trials [Available online: http://www.medicinesaustralia.com.au]
  3. Department of Health and Aging; Therapeutic Goods Administration (cited 9th December 2007) The Australian Clinical Trial Handbook [Available online: http://www.tga.gov.au/ct/cthandbook.pdf]
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  8. National Cancer Institute (cited 9th December 2007) Clinical Trials: A guide to understanding informed consent [Available online: http://www.cancer.gov/clinicaltrials/learning/what-is-a-clinical-trial] (last updated 23rd December 2003)
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