In Vivo

The literal translation of in vivo from Latin is “in the living being.” This phrase refers to those things occurring inside of a living entity. In vivo research refers to research performed within the tissue of a living being as opposed to research performed on dead materials or on specific metabolic components.

In vivo research is commonly used to observe the overall effects on the living organism being studied rather than one specific outcome. Accordingly, there are more external variables with in vivo research. Although optimal studies attempt to limit outside factors potentially confounding the project, results of studies are sometimes difficult to determine because there may be factors (both predicted and not predicted) that alter results or factors that alter the specific interpretation of results.

In vivo research, by definition, must be performed within the system in which it is meant to be used. New pharmaceuticals and compounds created in laboratories may prove worthless or even harmful to living tissue, and thus must be tested on live subjects. Live organisms used for these tests can vary from plants to mice to human subjects.

The value of in vivo testing is revealed in cases where, for instance, a substance that has been found to be active and effective in laboratory, in vitro tests virtually disappear when tested in vivo; this can happen because of the interaction of another in vivo factor that interacts negatively with the substance being tested.

In vivo research is generally conducted by pharmaceutical companies when testing new drugs; often, these in vivo trials involve human subjects. Typically, background research on the potential pharmaceutical being tested has already been conducted on individual metabolic components, and an intervention has been created to treat a medical condition.

In the United States and several other countries, clinical trials must be performed to evaluate new drugs/biologics, medical devices, and other interventions used on patients under scientifically controlled settings. Before the intervention can be released to the public, clinical research trials must be performed to determine safety and efficacy of the drug. The Food and Drug Administration (FDA) has published specific guidelines to be used during the in vivo clinical trials on human subjects.

Pharmaceutical trials are commonly described in four phases that occur over several years. If the studies demonstrate continued safety and efficacy during this time period, the drug development process typically proceeds. The initial phase involves the first testing in human subjects to observe the in vivo results and delineate safety, tolerability, pharmacokinetics, and pharmacodynamics upon a small group of healthy individuals. The second phase is designed to assess the in vivo results on a larger group of human subjects assessing clinical efficacy. The third phase is typically designed to delineate assessment of the efficacy compared to current standard of care therapies; larger groups of subjects are used for this phase. The final phase of pharmaceutical trials involves the postlaunch safety surveillance. Sometimes long-term or unexpected and rare adverse effects are discovered once larger groups of patient populations are using the treatment and undergoing the in vivo human subject exposure.

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