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In pharmacology
Pharmacology

Pharmacology is the study of drug action. More specifically it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function....
, the International Unit is a unit of measurement for the amount of a substance, based on measured biological activity
Biological activity

Pharmacological or biological activity is an expression describing the beneficial or adverse effects of a drug on organism. When the drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents....
 or effect. "International Unit" is abbreviated as IU, or as UI from the French
French language

French is a Romance language spoken around the world by around 80 million people as first language, by 190 million as second language, and by about another 200 million people as an acquired tongue, with significant speakers in 54 countries....
 unité internationale, or as IE from the German
German language

German is a West Germanic languages, thus related to and classified alongside English language and Dutch language. It is one of the world's world language and the most widely spoken mother tongue in the European Union....
 Internationale Einheit.

The unit is used for vitamin
Vitamin

A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. A compound is called a vitamin when it cannot be biosynthesis in sufficient quantities by an organism, and must be obtained from the diet....
s, hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s, some medication
Medication

A pharmaceutical drug, also referred to as medicine or medicament, can be loosely defined as any substance intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease....
s, vaccine
Vaccine

A vaccine is a biological preparation that establishes or improves immunity to a particular disease.Vaccines can be prophylaxis , or Medication ....
s, blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
 products, and similar biologically active substances.






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In pharmacology
Pharmacology

Pharmacology is the study of drug action. More specifically it is the study of the interactions that occur between a living organism and exogenous chemicals that alter normal biochemical function....
, the International Unit is a unit of measurement for the amount of a substance, based on measured biological activity
Biological activity

Pharmacological or biological activity is an expression describing the beneficial or adverse effects of a drug on organism. When the drug is a complex chemical mixture, this activity is exerted by the substance's active ingredient or pharmacophore but can be modified by the other constituents....
 or effect. "International Unit" is abbreviated as IU, or as UI from the French
French language

French is a Romance language spoken around the world by around 80 million people as first language, by 190 million as second language, and by about another 200 million people as an acquired tongue, with significant speakers in 54 countries....
 unité internationale, or as IE from the German
German language

German is a West Germanic languages, thus related to and classified alongside English language and Dutch language. It is one of the world's world language and the most widely spoken mother tongue in the European Union....
 Internationale Einheit.

The unit is used for vitamin
Vitamin

A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. A compound is called a vitamin when it cannot be biosynthesis in sufficient quantities by an organism, and must be obtained from the diet....
s, hormone
Hormone

Hormones are chemicals released by cells that affect cells in other parts of the body. Only a small amount of hormone is required to alter cell metabolism....
s, some medication
Medication

A pharmaceutical drug, also referred to as medicine or medicament, can be loosely defined as any substance intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease....
s, vaccine
Vaccine

A vaccine is a biological preparation that establishes or improves immunity to a particular disease.Vaccines can be prophylaxis , or Medication ....
s, blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
 products, and similar biologically active substances. Despite its name, the IU is not part of the International System of Units
International System of Units

The International System of Units is the modern form of the metric system and is generally a system devised around the convenience of the number ten....
 used in physics
Physics

Physics is the natural science which examines basic concepts such as energy, force, and spacetime and all that derives from these, such as mass, charge, matter and its Motion ....
 and chemistry
Chemistry

Chemistry is the science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions....
.

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 does not 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
World Health Organization

The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health....
 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
Mass

In physical science, mass refers to the degree of acceleration a body acquires when subject to a force: bodies with greater mass are accelerated less by the same force....
 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 is 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 is sufficient, simply, to specify the number of IUs of vitamin E.

The mass equivalents of 1 IU for selected substances are:

  • Insulin
    Insulin

    Insulin is a hormone with extensive effects on both metabolism and several other body systems . Insulin causes most of the body's cells to take up glucose from the blood , storing it as glycogen in the liver and muscle, and stops use of fat as an energy source....
    : 1 IU is the biological equivalent of about 45.5 µg
    Microgram

    In the metric system, a microgram is 1/1,000,000 of a gram , or 1/1000 of a milligram, is one of the smallest units of weight/mass commonly used....
     pure crystalline insulin (1/22 mg exactly)
  • Vitamin A
    Vitamin A

    Vitamin A, a bi-polar molecule formed with bi-polar covalent bonds between carbon and hydrogen, is linked to a family of similarly shaped molecules, the retinoids, which complete the remainder of the vitamin sequence....
    : 1 IU is the biological equivalent of 0.3 µg retinol
    Retinol

    Retinol, the animal form of vitamin A, is a fat-soluble vitamin important in visual system and bone growth. It is also a Terpenoid. Retinol is among the most useable forms of vitamin A, which also include Retinal , Retinoic acid and retinyl ester ....
    , or of 0.6 µg beta-carotene
    Carotene

    The term carotene is used for several related substances having the formula C40Hx, which are synthesized by plants but cannot be made by animals....
  • Vitamin C
    Vitamin C

    Vitamin C or ascorbic acid is an essential nutrient for humans, a large number of simian species, a small number of other mammalian species , a few species of birds, and some fish....
    : 1 IU is 50 µg L-ascorbic acid
    Ascorbic acid

    Ascorbic acid is a sugar acid with antioxidant properties. Its appearance is white to light-yellow crystals or powder. It is water-soluble. The L-enantiomer of ascorbic acid is commonly known as vitamin C....
  • Vitamin D
    Vitamin D

    Vitamin D is a group of fat-soluble prohormones, the two major forms of which are vitamin D2 and vitamin D3 . The term vitamin D also refers to metabolites and other analogues of these substances....
    : 1 IU is the biological equivalent of 0.025 µg cholecalciferol
    Cholecalciferol

    Cholecalciferol is a form of Vitamin D, also called vitamin D3 or calciol.It is structurally similar to steroids such as testosterone, cholesterol, and cortisol ....
    /ergocalciferol
  • Vitamin E
    Vitamin E

    Vitamin E is the collective name for a set of 8 related a-, ?-, ?-, and d-tocopherols and the corresponding four tocotrienols, which are fat-soluble vitamins with antioxidant properties....
    : 1 IU is the biological equivalent of about 0.667 mg d-alpha-tocopherol
    Tocopherol

    Tocopherol, a class of chemical compounds of which many have vitamin E activity, describes a series of organic compounds consisting of various methylated phenols....
     (2/3 mg exactly), or of 1 mg of dl-alpha-tocopherol acetate


Different from unit of enzyme activity


The IU should not be confused with the enzyme unit
Enzyme unit

The enzyme unit is a unit of measurement for the amount of a particular enzyme.One U is defined as that amount of the enzyme that catalysis the conversion of 1 micro mole of substrate per minute....
, also known as the International unit of enzyme activity and abbreviated as U.

External links

  • - Converting between IU and mg/mcg