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A laboratory rat with a brain implant, that was used to record in vivo neuronal activity. Studies that are in vivo (Latin for "within the living"; often not italicized in English [1] [2] [3]) are those in which the effects of various biological entities are tested on whole, living organisms or cells, usually animals, including humans, and plants, as opposed to a tissue extract or dead organism.
Typically, most candidate drugs that are effective in vitro prove to be ineffective in vivo because of issues associated with delivery of the drug to the affected tissues, toxicity towards essential parts of the organism that were not represented in the initial in vitro studies, or other issues. [33]
For drug development, the clinical phases start with testing for drug safety in a few human subjects, then expand to many study participants (potentially tens of thousands) to determine if the treatment is effective. [1] Clinical research is conducted on drug candidates, vaccine candidates, new medical devices, and new diagnostic assays.
The problem of transposing in vitro results is particularly acute in areas such as toxicology where animal experiments are being phased out and are increasingly being replaced by alternative tests. Results obtained from in vitro experiments cannot often be directly applied to predict biological responses of organisms to chemical exposure in vivo.
A bioassay is an analytical method to determine the potency or effect of a substance by its effect on living animals or plants (in vivo), or on living cells or tissues (in vitro). [1] [2] A bioassay can be either quantal or quantitative, direct or indirect. [3] If the measured response is binary, the assay is quantal; if not, it is quantitative ...
Then in vivo animal models, with different species, provide guidance on the efficacy and safety of the product for humans. With success in both in vitro and in vivo studies, scientist can propose that clinical trials test whether the product be made available for humans. Clinical trials are often divided into four phases.
An in-vitro in-vivo correlation (IVIVC) has been defined by the U.S. Food and Drug Administration (FDA) as "a predictive mathematical model describing the relationship between an in-vitro property of a dosage form and an in-vivo response". Generally, the in-vitro property is the rate or extent of drug dissolution or release while the in-vivo ...
It was coined in 1987 as an allusion to the Latin phrases in vivo, in vitro, and in situ, which are commonly used in biology (especially systems biology). The latter phrases refer, respectively, to experiments done in living organisms, outside living organisms, and where they are found in nature.