Clinical Trial Phases Clinical Trials

Clinical Trial Phases Clinical Trials The four phases of clinical trials Approving a drug's safety for public use is a serious decision, and the Food and Drug Administration (FDA) makes use of a multi-tiered strategy before giving its seal of approval to a new pharmaceutical or treatment. The clinical trials or research used by the FDA take place after initial, non-human experimentation has occurred.

Whether interventional (taking place under controlled circumstances) or observational (taking place in natural settings) in nature, four distinct phases must be passed through (What is a clinical trial, 2006, NIH). During Phase I, the new drug or treatment is tested upon a very small group of people, usually 20-80 individuals, under controlled circumstances. This is the first time the drug has been in general use, and the study is done "to evaluate its safety, determine a safe dosage range, and identify side effects" (What are clinical trial phases, 2006, NIH).

Phase I studies also "determine the metabolism and pharmacologic actions of drugs in humans, the side effects associated with increasing doses" and are designed accumulate evidence suggesting effectiveness (Understanding clinical trials, 2006, NIH). The studies may be conducted upon healthy volunteers as well as patients that may or may not represent the drug's likely users. If the target population is in fragile health but it is deemed safe for healthy participants to take the drug, the target population might not be used at all.

During Phase II, trials, the experimental population is expanded to a larger group of people (100-300) to further test the drug's efficacy and safety. These studies, like Phase I trials, take place under controlled conditions rather than in 'the field' or in the context of the study participants' everyday lives.

They are more specific as well as larger than Phase I studies as they evaluate "the effectiveness of the drug for a particular indication or indications in patients with the disease or condition under study" and "determine the common short-term side effects and risks" in a more specific fashion than was possible under the very small Phase I studies, where anomalies particular to the population may be reported as side effects (Understanding clinical trials, 2006, NIH).

During Phase III, the drug or treatment is administered under expanded, controlled and uncontrolled conditions in trials of 1,000-3,000 or more persons. They are conducted only "after preliminary evidence suggesting effectiveness of the drug has been obtained" (Understanding clinical trials, 2006, NIH). These studies conduct cost or risk-benefit analysis of taking the drug and compare the benefits of the drug or treatment to existing options (Understanding clinical trials, 2006, NIH).

A drug may be effective, but its side effects may be far more severe than current treatments, and if it provides no additional benefit than existing treatments, the drug may not be approved. Information is also collected to determine when the drug is safe to use, and under what conditions. For example, certain drugs such as MAOIs cannot be taken with other drugs or eaten with certain foods without causing severe health problems; some sedating medications should not be taken when the user will be driving within a few hours.

At the final phase, Phase IV, "studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and.