International unit Totally Explained

Everything about International Unit totally explained

In pharmacology, the International Unit is a unit of measurement for the amount of a substance, based on measured biological activity or effect. "International Unit" is abbreviated as IU, or as UI from the French unité internationale, or as IE from the German Internationale Einheit. The unit is used for vitamins, hormones, some medications, vaccines, blood products, and similar biologically active substances. Despite its name, the IU isn't part of the International System of Units used in physics and chemistry.
   The precise definition of one IU differs from substance to substance and is established by international agreement for each substance. There is no equivalence among different substances; for instance, one IU of vitamin E doesn't contain the same number of milligrams as one IU of vitamin A.
   To define an IU of a substance, the Committee on Biological Standardization of the World Health Organization provides a reference preparation of the substance, arbitrarily sets the number of IUs contained in that preparation, and specifies a biological procedure to compare other preparations of that substance to the reference preparation. The goal in setting the standard is that different preparations with the same biological effect will contain the same number of IUs.
   For some substances, the equivalent mass of one IU is later established. If that happens, the former IU definition for that substance is officially abandoned, in favor of a newly established weight. However, the unit count often remains in use nevertheless, because it's convenient. For example, vitamin E exists in a number of different forms, all having different biological activities. Rather than specifying the precise type and mass of vitamin E in a preparation, for the purposes of pharmacology it's sufficient, simply, to specify the number of IUs of vitamin E.
   The mass equivalents of 1 IU for selected substances are:

Insulin: 1 IU is the biological equivalent of about 45.5 μg pure crystalline insulin (1/22 mg exactly)
Vitamin A: 1 IU is the biological equivalent of 0.3 μg retinol, or of 0.6 μg beta-carotene
Vitamin C: 1 IU is 50 μg L-ascorbic acid
Vitamin D: 1 IU is the biological equivalent of 0.025 μg cholecalciferol/ergocalciferol
Vitamin E: 1 IU is the biological equivalent of about 0.667 mg d-alpha-tocopherol (2/3 mg exactly), or of 1 mg of dl-alpha-tocopherol acetate

Different from unit of enzyme activity

The IU shouldn't be confused with the enzyme unit, also known as the International unit of enzyme activity and abbreviated as U.

Further Information

Get more info on 'International Unit'.

External Link Exchanges

Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:

<a href="http://international_unit.totallyexplained.com">International unit Totally Explained</a>

Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned.