A clinical research program, also known as a clinical trial, is a common form of scientific medical research used to test the effectiveness and safety of new drugs and surgical techniques. These trials typically take in volunteer patients, some of whom receive the drug being tested, and others of whom function as a control group (which is given either no treatment, i.e. a placebo, or the most common treatment outside of the study). In many countries, including in the United States and Europe, a new drug will not be approved for use until a number of clinical trials have been done establishing that the drug is both safe and effective.
Clinical trials may be done to test new drugs, or they may be done to compare the effectiveness of different regimens of existing drugs. When they are done for the first purpose, they often involve recently developed drugs (or new purposes for existing drugs) which have not been approved by government bodies responsible for overseeing medicine, such as the Food and Drug Administration (FDA) in the U.S. In these cases, there are several standard stages in the trial process, known as phases. All human testing is proceeded by laboratory tests involving animals.
In the first phase (Phase I) of clinical trials in humans, a very small group of subjects (perhaps a dozen, usually less than 100) are recruited. At this point, the medical researchers will have already done substantial laboratory tests involving animals, so that they both have a genuine belief that the drug should be effective, as well as that it should be safe at the levels at which it will be administered. However, because neither is certain, the drug is given only to a small number of patients. At this point, researchers typically only have a vague idea what the most effective dose would be – or, more accurately, the level at which the dose is relatively effective without being high enough to cause dangerous side effects.
This first group of subjects may show dramatic improvements (and often times, they do), but a Phase I trial is not really set up to cure patients. Indeed, even if there is virtually no meaningful response to therapy, clinical trials usually progress to Phase II anyways. This is because the Phase I hurdle exists less to treat the patients in the trial than to establish doses at which the drugs are safe and probably effective. Phase II trials then recruit a somewhat larger group of patients, who are then used to assess how effective the drug seems to be.
The final set of clinical trials are referred to as Phase III. A drug in a Phase III trial should have, at least in the opinion of the researchers, proven itself as a genuine potential treatment for the condition in question. The researchers will next attempt to demonstrate its effectiveness compared to either a placebo (no treatment, such as a sugar pill) or to the standard accepted treatment for the condition. In the Phase III trial for a new cancer drug, for instance, patients may be randomly divided into two groups, one of which is given the standard chemotherapy regimen for that cancer (and functions as the control group), and the other of which is given the new drug or new drug combination. A drug may be a success at Phase III if it is more effective than existing drugs, if it is similarly effective but noticeably less toxic (i.e. reduced side effects), or, of course, if it is both more effective and less toxic.
Once a drug has passed Phase III and been approved for use, follow-up studies may be done assessing long-term effects or other issues related to the drug. These are sometimes referred to as Phase IV studies. While they are not necessarily less important, they are not a component of the standard three-part model for human testing of new drugs.
Today, there are a large number of clinical trials going on at any one time, and many of these make use of expensive new targeted therapies for chronic and life-threatening conditions, such as cancer. Obtaining sufficient funding and ethics approval for clinical trials has become both difficult and cumbersome, and in the past there have been some instances where critics questioned the neutrality and validity of research trials conducted to test certain drugs, with funding supplied by the makers of those drugs.