What Is A Clinical Trial?
A clinical trial is the procedure whereby a new drug or treatment is given to a group of volunteers and compared to an established treatment, if one exists, or a placebo ("sugar pill") to see if it is safe and effective. Most clinical trials are sponsored by the federal government or pharmaceutical companies. Clinical trials advance medical knowledge by providing information about whether a new untested treatment is useful and whether it should be recommended for widespread use.
Enrolling in a clinical trial as a volunteer patient, also called subject, is one way you can receive a new experimental treatment. To choose the best subjects, each clinical trial defines very specific characteristics called inclusion criteria. The persons running the trial, called investigators, create inclusion criteria to select a group of patients most likely to benefit from the new treatment. For example, inclusion criteria for a study evaluating treatment for Pneumocystis carinii pneumonia (PCP) would require that the subject be HIV-infected and have PCP.
Each clinical trial also has its own exclusion criteria, which are reasons that may disqualify you from participating. Exclusion criteria are intended to prevent patients from enrolling if they are at risk for serious complications or harm from the new treatment. They may also be excluded if they have medical conditions that would make it difficult to detect the effect of the treatment being tested. For example, patients who have severe anemia (very low red blood count) or poor kidney or liver function are often excluded from participation.
Clinical trials for any one treatment are carried out in several phases, first to show its safety and later to test its effectiveness.
- Phase I trials determine the safety and side effects of the drug being studied and the highest dose that can be tolerated. They usually include a small number of subjects and last days to weeks.
- Phase II trials assess whether a new drug is effective and may test different doses to find the best one. Phase II trials enroll a larger number of subjects.
- Phase III trials continue to collect information on the drug's effectiveness and side effects and enroll an even larger number of subjects. They generally last months to years.
- Phase IV: Following drug approval by the U. S. Food and Drug Administration (FDA), some subjects in phase III may be offered participation in phase IV trials to address any still unanswered questions about the medication.
to participating in a clinical trial may include health benefits from the new treatment; free laboratory tests and results; access to treatments not available to the public; free supplies of standard or new drugs; regular medical examinations and a sense of satisfaction from improving the care of others with HIV disease.
Disadvantages to participating in a clinical trial may include taking new drugs that turn out not to be beneficial or to have side effects or negative long term consequences; not knowing whether you are receiving the actual therapeutic drug or a placebo; more frequent visits for care than would otherwise be necessary; and being restricted from using other treatments or participating in other studies because of requirements of the clinical trial.
Before participating in a clinical trial, you will be evaluated to see that you meet specific inclusion and exclusion criteria. This evaluation is generally performed by a nurse or physician's assistant and includes a medical history and/or series of laboratory tests. You will be asked to give informed consent, which means that you understand the potential benefits and risks of receiving a new treatment and agree to them.
An informed consent form is a legal document that identifies all known benefits of the clinical trial, describes what is involved, explains what happens after the study is completed, tells who is responsible for what activities, and defines your rights as a subject. If you do not speak English, informed consent should be provided to you in your native language. If you find it difficult to read or understand the document, you may request that it be read to you. It is often a good idea to take the informed consent form home so that you can review it thoroughly. You should be sure that all of your questions are answered satisfactorily by the doctor or nurse who works with you in the clinical trial before agreeing to participate.
If you have questions at any time during the clinical trial, you may ask your regular clinician or person working for the study. You have the right to stop participating in a clinical trial for any reason at any time without prejudicing your care. When the clinical trial has been completed, you will be notified of the results, and your primary care provider will review the options available for treatment of your condition.
Several different clinical trial systems have been established for HIV-infected persons, including the AIDS Clinical Trial Group (ACTG), the Community Programs for Clinical Research on AIDS (CPCRA), and the Community Based Clinical Trial Network (CBCTN).
An ACTG trial is usually based at a particular hospital. You will have to go there for medical visits, and it may be a different location from where your primary care provider practices. The experimental drug and laboratory testing are provided free of charge.
A CPCRA trial is conducted in collaboration with your primary care doctor. You may be seen at your doctor's office or another location by a nurse who will do an initial evaluation and monitor your progress. Most laboratory studies will be performed in the same manner as is normally required by your primary care provider. The experimental drug is provided free of charge, and laboratory tests are either paid for by the clinical trial or billed to your insurance.
A CBCTN trial is very similar to a CPCRA trial. You will be seen at your doctor's office by either a provider working for the clinical trial or your primary care provider. Most laboratory studies will be performed as normally requested by your doctor. The experimental drug is provided free of charge. If your doctor or nurse sees you for the study, your insurance company may be billed for an office visit. A feature of the CBCTN system is the availability of trials that are generally not offered through the ACTG system.
The U.S. FDA regulates the availability of all new drugs. If the FDA has not yet approved a new drug for sale, but it has been extensively tested in human subjects, the pharmaceutical company may request its use for treatment of patients who meet certain criteria. A medication with this status is said to be an expanded access drug. Your doctor will apply to the pharmaceutical company for you to participate in this program, and it requires informed consent.
Another procedure for obtaining a new medication is through a compassionate use request, which makes an experimental medication available for patients with serious illness. Your doctor applies to the pharmaceutical company and FDA, and approval is considered on a case-by-case basis. For more information about expanded access drugs, contact the FDA Center for Drugs at 1-301-827-4570.
When a clinical trial has been completed or when an answer has been reached concerning the safety and efficacy of an experimental drug, an application is made to the FDA for approval. Once this is granted, the drug is made available for general distribution through pharmacies.
