international unit

international unit
1. an internationally agreed upon standard, as measured by bioassay, to which samples of a substance, as a drug or hormone, are compared to ascertain their relative potency.
2. the particular quantity of such a substance, which causes a specific biological effect. Abbr.: IU

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Any of several precision standards used in measuring physical quantities, such as mass, length, and time (see International System of Units), and also lighting systems, radiation processes, and pharmacology.

The luminous intensity or candlepower of a light is expressed in candelas. The second is based on the frequency of radiation emitted by cesium-133 atoms. In radioactive decay, the international unit is the number of disintegrations per second in a sample. In pharmacology, the international unit is the quantity of a substance (vitamin, hormone, or toxin) that produces a specified effect when tested according to an internationally accepted procedure.

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▪ unit of measurement
      in pharmacology, quantity of a substance, such as a vitamin, hormone, or toxin, that produces a specified effect when tested according to an internationally accepted biological procedure. For certain substances, the IU has been identified with a weight of a particular purified form of the material; for example, one gram of vitamin A acetate contains 2.904 × 106 IU. For international units of physical quantities, such as mass, length, etc., see International System of Units.

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Universalium. 2010.

Look at other dictionaries:

  • international unit — n the amount of specific physiological activity of a standardized preparation (as of a vitamin) that is agreed upon as an international standard esp. for comparison with other biologicals containing the substance in impure form or with a related… …   Medical dictionary

  • International unit — In pharmacology, the International Unit is a unit of measurement for the amount of a substance, based on biological activity or effect. It is abbreviated as IU, as UI (Spanish unidad internacional or French unité internationale or Italian unità… …   Wikipedia

  • international unit — noun A particular, minute unit of mass, defined differently for different substances, but so that varying substances of the same general type have the property that one international unit of the one has the same effect on the human body as one… …   Wiktionary

  • international unit — tarptautinis vienetas statusas T sritis fizika atitikmenys: angl. international unit vok. internationale Einheit, f rus. международная единица, f pranc. unité internationale, f …   Fizikos terminų žodynas

  • international unit — (IU)    a unit used to measure the activity (that is, the effect) of many vitamins and drugs. For each substance to which this unit applies, there is an international agreement specifying the biological effect expected with a dose of 1 IU. Other… …   Dictionary of units of measurement

  • International Unit — IU. A unit used to measure the activity of many vitamins, hormones, enzymes, and drugs. An IU is the amount of a substance that has a certain biological effect. For each substance there is an international agreement on the biological effect that… …   English dictionary of cancer terms

  • international unit — noun a unit of activity for a particular vitamin, hormone, etc. in terms of the activity of a standard quantity …   English new terms dictionary

  • international unit — /ɪntəˌnæʃnəl ˈjunət/ (say intuh.nashnuhl yoohnuht) noun a unit of the amount of a biologically active substance, such as a vitamin or hormone, required to produce a specific response …   Australian-English dictionary

  • international unit — noun Date: 1922 a quantity of a biologically active substance (as a vitamin) that produces a particular biological effect agreed upon as an international standard …   New Collegiate Dictionary

  • international unit — in′terna′tional u′nit n. 1) pha an internationally accepted standard, derived by bioassay, to which samples of a pharmaceutical substance are compared for ascertaining their relative potency 2) pat the specific biologically effective quantity of… …   From formal English to slang

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