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Chance Agrella
Clinical trials are usually divided into different phases. Each phase has a specific design and is conducted to gather particular information about the material or modality being investigated. Pre-clinical tests involve animal studies and in vitro tests, performed strictly in a laboratory environment such as with test tubes.
Phase I Trials
This phase is for drugs or treatments never used in humans and is designed to evaluate potential side effects and safe dose ranges. They usually involve small numbers of healthy volunteers, so any side effects will not be confused with existing conditions. These studies are usually brief and involve small numbers of patients, who are monitored closely because of risks. These are often referred to as safety trials. These studies are not randomized. All volunteers received the active treatment, not a placebo. Volunteers and investigators are aware of the treatments involved.
Phase II Trials
After a drug or treatment is shown to be safe and well tolerated, Phase II trials begin to establish efficacy. Studies involve larger groups of patients who have the disease or the potential for the disease being studies. These trials can be randomized, where the active treatment is compared to a placebo, but not always. Safety evaluations continue in this phase.
Phase III Trials
If the investigational treatment is effective in Phase II trials, Phase III trials may begin. Phase III trials expand on the success of earlier trials by evaluating hundreds or even many thousands of patients. Phase III trials are always randomized. Usually, neither the investigator nor the volunteer is aware of whether they are getting an active agent, a placebo, or an existing standard treatment.
Phase IV Trials
These trials are referred to as Post-Marketing Trials because they are conducted after a treatment has been on the market, providing valuable data on long-term usage. These studies can reveal side effects not apparent during Phase III and also identify new uses for existing treatments.
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