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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]
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.
Such studies involve in vitro (test tube or cell culture) and in vivo (animal model) experiments using wide-ranging doses of the study agent to obtain preliminary efficacy, toxicity and pharmacokinetic information.
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 ...
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 ...
In drug development, preclinical development (also termed preclinical studies or nonclinical studies) is a stage of research that begins before clinical trials (testing in humans) and during which important feasibility, iterative testing and drug safety data are collected, typically in laboratory animals.
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.