FREQUENTLY ASKED QUESTIONS
General Questions
5. WHAT IS CLINICAL RESEARCH AND WHAT ARE HUMAN CLINICAL TRIALS?
(Taken from Unit I, Chapters 2 and 3, of the
Rx for Science Literacy teacher manual.)
Clinical Research
Information gained through basic and applied research often leads to potential treatments to prevent or cure disease. Once all other forms of study and testing have taken place, scientists look to clinical research to test potential drugs and treatments in humans. This research builds upon that done in the basic and applied research stages. However, clinical research is not always the end of the process. Often, it leads back to the lab, where further research is done. It is this interdependence that at times makes science seem so complex.
Clinical research takes place in a hospital or other clinical setting for health care and directly applies to the prevention, diagnosis or treatment of a specific disease in an individual or group of individuals, or to the rehabilitation of the patient. Clinical research includes a broad variety of activities, and there are many areas of study. These areas include human clinical trials, psychosocial and behavioral research and disease-control research.
Scientists and other biomedical researchers are continually striving to improve human health care, and the success of new surgical techniques and other therapies to reduce human pain and suffering capture media and public attention.
In the area of cancer research, basic and applied research findings have led the way to clinical research focused on prevention and/or early detection such as:
- Pap test: Dr. George Papanicolaou's studies showed that a sample of cells from a patient's cervix could detect the early stages of cancer. The Pap test has helped to produce a 70 percent reduction in the number of deaths due to cervical cancer.
- Smoking: Research findings that showed lung cancer is significantly associated with smoking and that smokers die more often of heart attacks formed the basis of the American Cancer Society’s smoking control programs.
(Information for this section is used with permission from Science for Life: Exploring Animal Models in Biomedical Research, 1993, Florida State University.)
Human Clinical Trials
Introduction: Human clinical trials are an important component of the biomedical research process and are most often used in developing prescription drugs. Even after a promising new drug has undergone extensive laboratory research and testing, scientists still need actual human data from controlled studies to answer two key questions: Is the drug biologically active in humans? And, is it safe in humans?
There are three major phases of clinical trials that begin after a pharmaceutical firm files an Investigational New Drug (IND) application with the Food and Drug Administration (FDA). In the IND, a pharmaceutical firm shows the results of laboratory testing and explains how the drug is made.
In Phase I clinical trials, researchers determine a drug’s interaction with the human system, including how it is absorbed, distributed, metabolized and excreted, and the likely duration of its therapeutic effect. This phase involves a small number of healthy volunteers and takes approximately one year.
Phase II trials use controlled tests that help determine a drug’s effectiveness. These studies involve 100 to 300 volunteer patients. Simultaneous animal and human tests are also conducted at this stage as researchers continue to assess the safety of the drug. This phase takes approximately two years.
Phase III trials are conducted to confirm the results of earlier efficacy tests and further identify any adverse reactions. Clinical testing at this point is extensive, involving 1,000 to 3,000 volunteer patients in medical clinics and hospitals. This phase takes approximately three years.
After human clinical trials are completed, firms file a New Drug Application (NDA) with the FDA. The NDA is a comprehensive statement of the information on: drug structure, the scientific rationale and purpose of the drug therapy, pre-clinical animal and other laboratory study results, all human clinical testing results, drug formulation and production details and the company’s proposed labeling. This takes approximately 2.5 years to complete.
Currently, it takes approximately 12 years from initiation of animal and other laboratory studies through all phases of clinical trials and submission of data to the FDA for approval. For each new medicine approved, the cost is hundreds of millions of dollars.
Example: The first human trials of a hormonal growth factor called stem cell factor (SCF) indicate that cancer patients treated with SCF recover more quickly from standard chemotherapy than would otherwise be expected.
Strengths: Human clinical trials provide actual human data on the efficacy and safety of promising new drugs.
Limitations: Ethical and moral considerations limit the extent to which human volunteers can be used as test subjects for a potential new drug.
Such trials also require extensive pre-clinical testing before they can be conducted.
In addition, numerous variables, which may affect the test data, are introduced whenever humans are used as test subjects. These include genetic makeup, exposure to other chemicals, disease history, etc.
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