Clinical Trials Factsheet

Clinical Trials Factsheet

A clinical trial is a biomedical or health-related research study carried out with humans to determine the safety and efficacy of a new drug or treatment. A clinical trial can only take place once information has been gathered on the quality of the drug and its non-clinical safety. e-pill Clinical Trials

In a recent Swedish register study, a limited number of specific drugs explained a large part of clinically relevant, potential drug-drug interactions (DDI), as defined and detected by the DDI database SFINX. Regarding interactions that should be avoided according to the definition in the database (class D), 15 drug combinations accounted for as much as 80 % of the prevalence in the Swedish population. Ten specific drugs were involved in 94 % of all detected class D interactions. About half of the clinically relevant interactions detected during the four-month study period were associated with an increased risk of adverse drug reactions, whereas the other half has a potential to cause therapeutic failure. An increased awareness among prescribers of these interacting drugs could contribute to safer and more effective drug use. Learn more: Link

Clinical trials can vary in size from a single center in a single country to multiple centers in multiple countries. In the U.S., the Food and Drug Administration (FDA) is responsible for establishing regulations and guidelines for clinical research and for overseeing clinical trials in order to protect the rights of participants and to verify the quality and integrity of the data. The FDA also reviews New Drug Applications, which are submitted by the drug sponsor at the conclusion of a Phase III trial to seek approval for marketing of a new drug in the U.S.

Learn more: Medication Adherence Clinical Studies.

Clinical trials are conducted in phases; the trials at each phase have a different purpose and help researchers to answer different questions. The four phases of clinical trials are:



Phase I (phase one): Researchers test an experimental drug in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify any side effects. Usually, healthy participants are enrolled in Phase I studies but in cancer, Phase I trials are conducted in patients rather than healthy volunteers.



Phase II (phase two): Phase II trials continue to test the safety of the drug, and begin to evaluate how well the experimental drug works in treating a certain disease or condition. The drug is given to a larger group of people and may involve a control group who receive either the current standard treatment or a placebo.



Phase III (phase three): Phase III trials are longer-term studies. The experimental drug is given to large groups of people (several hundred to thousands) to gather additional information about effectiveness, safety and side effects, to compare it to other treatments commonly used for the disease or condition, and to collect information that will allow the drug to be used safely. At the end of most Phase III trials, the new drug will be found to be inferior, equal or superior to the standard treatment. Based on favorable results, the drug may at this phase be approved to be sold to the public.



Phase IV (phase four): A Phase IV trial may take place after the drug has been on the market to further examine the drug’s risks, benefits and optimal use in ‘real-life’ conditions. Phase IV studies can also include trials of different doses or schedules of administration, other stages of disease, cost studies, quality-of-studies or use of the drug over a longer period of time.



A clinical trial may be ‘blinded’ so that the expectations of a drug’s effects will not influence observed results. In a ‘single-blinded’ trial, participants do not know which treatment they are receiving until the end of the study. In a ‘double-blinded’ study, neither the researchers nor the participants know which treatment the participant has received until the end of the study.