Depending on the type of product and the stage of its development, investigators enroll healthy volunteers and/or patients into small pilot studies initially, followed by larger scale studies in patients that often compare the new product with the currently prescribed treatment. As positive safety and efficacy data are gathered, the number of patients is typically increased. Participants in clinical trials can gain access to new treatments before they are widely available, and help others by contributing to medical research.
Due to the sizable cost a full series of clinical trials may incur, the burden of paying for all the necessary people and services is usually borne by the sponsor who may be a governmental organization, a pharmaceutical, or biotechnology company. Since the diversity of roles may exceed resources of the sponsor, often a clinical trial is managed by an outsourced partner such as a contract research organization or a clinical trials unit in the academic sector.
Randomized A randomized controlled trial is the study design that can provide the most compelling evidence that the study treatment causes the expected effect on human health. Each study subject is randomly assigned to receive either the study treatment or a placebo.
Blind The subjects involved in the study do not know which study treatment they receive. If the study is double-blind, the researchers also do not know which treatment is being given to any given subject. This 'blinding' is to prevent biases, since if a physician knew which patient was getting the study treatment and which patient was getting the placebo, he/she might be tempted to give the (presumably helpful) study drug to a patient who could more easily benefit from it. In addition, a physician might give extra care to only the patients who receive the placebos to compensate for their ineffectiveness. A form of double-blind study called a "double-dummy" design allows additional insurance against bias or placebo effect. In this kind of study, all patients are given both placebo and active doses in alternating periods of time during the study.
Placebo-controlled The use of a placebo allows the researchers to isolate the effect of the study treatment. A placebo is an inactive pill, liquid, or powder that has no treatment value. In clinical trials, experimental treatments are often compared with placebos to assess the experimental treatment's effectiveness. In some studies, the participants in the control group will receive a placebo instead of an active drug or experimental treatment.
Although the term "clinical trials" is most commonly associated with the large, randomized studies typical of Phase III, many clinical trials are small. They may be "sponsored" by single physicians or a small group of physicians, and are designed to test simple questions. In the field of rare diseases, like gene therapy treatments of inherited disorders, sometimes the number of patients might be the limiting factor for a clinical trial.
To be ethical, researchers must obtain the full and informed consent of participating human subjects. If the patient is unable to consent for themself, researchers can seek consent from the patient's legally authorized representative. Informed consent is clearly a necessary condition for ethical conduct but does not ensure ethical conduct. In some U.S. locations, the local IRB must certify researchers and their staff before they can conduct clinical trials. For instance, they must understand good clinical practice. International Conference of Harmonisation Guidelines for Good Clinical Practice (ICH GCP) is a set of standards used internationally for the conduct of clinical trials. The guidelines aim to ensure that the "rights, safety and well being of trial subjects are protected".
Clinical trials that are well-designed and well-executed are the best approach for eligible participants to play an active role in their own health care, gain access to new research treatments before they are widely available, obtain expert medical care at leading health care facilities during the trial, and help others by contributing to medical research.
There are always certain risks or side effects to clinical trials. There may be unpleasant, serious or even life-threatening side effects to experimental treatment. The experimental treatment may not be effective for the participant. The protocol may require more of their time and attention than would a non-protocol treatment, including trips to the study site, more treatments, hospital stays or complex dosage requirements. Side effects are any undesired actions or effects of the experimental drug or treatment. Negative or adverse effects may include headache, nausea, hair loss, skin irritation, or other physical problems. Experimental treatments must be evaluated for both immediate and long-term side effects.