• PDtrials - Parkinson's Disease Clinical Trials
• /Clinical Research 101

A clinical trial  Clinical Trial (Clinical Study)A scientific study involving human participants to determine the safety and efficacy of new therapies or new ways of using known treatments. (also called medical research, clinical  ClinicalDealing with or based on observation and treatment of people, as opposed to basic science carried out in the laboratory or in animals. research or a clinical study) is a study intended to help answer specific questions about a treatment by studying its effects in people. Clinical trials are designed and conducted by scientists and medical experts, who invite people to participate in testing the new therapy  TherapyAnother word for “treatment”. or treatment. The purpose of a clinical trial is usually to test the safety and efficacy  EfficacyThe extent to which a specific intervention, procedure, or regimen produces a beneficial result under ideal conditions. of new treatments. Clinical trials may also be conducted to learn other things about medical treatments or procedures such as how the treatment interacts with other drugs. Clinical trials are an essential and necessary component of the scientific research process. It is only through clinical trials that new medications and treatments become available! Clinical trials that test new treatments or therapies in the U.S. are regulated by the Food and Drug Administration  Food and Drug AdministrationThe U.S. Department of Health and Human Services is the agency responsible for ensuring the safety and effectiveness  EffectivenessAbility of a drug or treatment to produce a result. of all drugs, biologics, vaccines, and medical devices. Internet address: http://www.fda.gov. (FDA), and overseen by medical and scientific experts whose role is to protect participants from unnecessary risk and to ensure that the research study is appropriately designed to answer the questions that need to be addressed.

Clinical trials are conducted and carefully monitored in a series of phases.

Phase I: This phase begins after researchers have completed pre-clinical  Pre-clinicalTesting of investigational drugs or treatments in the laboratory or in animals before trials in humans are carried out. laboratory and animal studies. A therapy is tested in trials of approximately 20 to 80 otherwise healthy individuals for safety, to establish how the medication is metabolized and to determine the safety of different dosage levels.

Phase II: These studies are designed to further define the safety of the therapies being tested, and to provide preliminary measures of effectiveness. Researchers will study the effects of the medication on a larger number of study participants – usually 100 to 300. They continue to monitor participants closely to ensure that the drug is safe and well tolerated in humans.

Phase III: This step is designed to measure whether the treatment actually benefits people with Parkinson’s, and whether its benefits exceed its risks. Phase III trials  Phase III TrialsPhase of drug testing in which the study drug or treatment is given to large groups of people (1,000-3,000) to determine the drugs effectiveness, side-effects, tolerability. tend to run over longer periods of time and with still larger populations (sometimes as many as 1,000 to 3,000 participants).

Many of these trials divide participants into two groups: a control group,  Control Group (Comparison Group)Clinical trial participants who are given either a standard treatment or a placebo instead of the investigational drug or treatment being tested. in which the individual is given the comparison treatment,  Comparison TreatmentTreatment used as a relative measure in controlled trials to “test” a treatment or “prove” its effectiveness in the absence of some absolute or relative measure of success. The effect of a treatment is measured against a comparison treatment administered over the same time period and under similar conditions. and an experimental group,  Experimental GroupStudy participant group which receives the drug, device, treatment, or intervention under investigation, rather than the standard treatment for the illness or a placebo. which receives the treatment being tested. Each group is equally important.

Most of these trials are so-called double-blind  Double-blindClinical study design in which neither investigators nor participants know who is receiving the investigational drug and who is receiving a placebo. trials in which neither the participants nor the researchers know who is receiving the “test” treatment and who is receiving the comparison treatment . This is to ensure objectivity. The comparison treatment could be a different dose of the “test” treatment, a treatment that is already available that is considered standard therapy for the disease, or placebo.  PlaceboAn inactive substance or procedure (often a pill, liquid, or powder) that has no biological effect. In clinical trials, experimental treatments are often compared with placebos to assess the treatment's effectiveness. In some studies, the participants will be assigned to a control group and will receive a placebo instead of an active drug or treatment. A placebo is an inert substance that looks like the drug being tested but has no medical activity.

Some studies are open-label  Open-labelA trial design that allows the researcher and the study participant to know what treatment the participant is receiving. This is the opposite of double-blind study. trials, where the participants know what is being tested and what treatment and dose they are receiving. For all trials, the study team consists of medical professionals who monitor the study participants for safety, tolerability and the efficacy of the treatment.

Phase IV: If the previous studies are successful, they lead to applications for approval from the FDA. Once approved for a specific medical condition, these treatments can be made available to the open market. Some treatments may be further tested in the general population in Phase IV trials  Phase IV TrialsPost-approval phase of drug testing to examine the effects of drugs once they are available and used by the public. This phase provides additional information including the drug's risks, benefits, and how best to use it. – possibly to see how they might help people with other conditions. Phase IV trials also test the effect of different dose levels and give researchers a better picture of any long-term effects.