Phase III trials involve large numbers of patients who are divided into groups who either receive the experimental treatment or act as controls. The control subjects don't receive the treatment or receive a placebo instead of the treatment. The groups are usually selected randomly. In masked studies, neither the patient nor the doctor knows in which group the particular patient is enrolled. A clinical trial is a research study to answer specific questions about vaccines, therapies or new ways of using known treatments.
Clinical trials are the next step after research in the lab produces promising results.
All clinical trials are based on a set of rules called a protocol. A protocol describes what types of people may participate in the trials, the schedule of tests, procedures, medications and dosages and length of the study. While in a clinical trial, participants are regularly monitored by the research staff to determine the safety and effectiveness of their treatment. There are four phases associated with a clinical trial. Phase I involves testing in 20 - 80 people to evaluate the drug's safety and determine a safe dosage range and identify side effects.