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Introduction to Clinical Trials for Parkinson's Disease

You may have heard about clinical trials from your doctor, read or heard advertisements in the newspaper or on the radio, or found out about trials in your area through a support group or association. Before you decide to participate in a trial, you should be aware of the potential benefits and risks. This guide provides a brief overview of the clinical trial process.

What Is a Clinical Trial?

A clinical trial is a research program conducted in patients to evaluate a new medical treatment, drug, or device. The purpose of clinical trials is to find new and improved methods of treating diseases and special conditions.

During a clinical trial, doctors use the best available treatment as a standard to evaluate new treatments. The new treatments are hoped to be at least as effective as -- or possibly more effective than -- the standard.

New treatment options are first researched in the laboratory, where they are carefully studied in the test tube and in animals. Only the treatments most likely to work are further evaluated in a small group of humans prior to applying them in a larger clinical trial.

When a new medical treatment is studied for the first time in humans, scientists don't know exactly how it will work. With any new treatment, there are possible risks as well as benefits. Clinical trials help doctors discover the answers to these questions:

• Is the treatment safe and effective?
• Is the treatment potentially better than the treatments currently available?
• What are the side effects of the treatment?
• Does the treatment have any possible risks?
• How well does the treatment work?

How Does the Clinical Trial Process Work?

Clinical trials are conducted in phases -- each designed to find out specific information. Each new phase of a clinical trial builds on information from previous phases.

Participants may be eligible for clinical trials in different phases, depending on the participants' overall condition. Most clinical trial participants take part in phases III and IV.

In a phase I clinical trial, a new research treatment is given to a small number of participants. The researchers determine the best way to give the new treatment and how much of it can be given safely.

Phase II clinical trials determine the effectiveness of the research treatment on the disease or condition being evaluated.

Phase III clinical trials compare the new treatment with the standard treatment.

Phase IV clinical trials apply the new treatment to patient care. For example, a new drug that was found effective in a clinical trial may then be used together with other effective drugs to treat the particular disease or special condition in a select group of patients.