a unit used in the United States to measure the potency of a vitamin or drug, that is, its expected biological effects. For each substance to which this unit applies, the U. S. Food and Drug Administration has determined the biological effect associated with a dose of 1 USP unit. Other quantities of the substance can then be expressed in terms of this standard unit. In most cases, the USP unit is equal to the international unit (IU). "USP" is a registered trademark of the United States Pharmacopeial Convention, Inc., a private standards organization that establishes standards for the pharmaceutical industry.
international unit (IU)
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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 quantities of the substance are then expressed as multiples of this standard. Examples: 1 IU represents 45.5 micrograms of a standard preparation of insulin or 0.6 microgram of a standard preparation of penicillin. Consumers most often see IU's on the labels of vitamin packages: in standard preparations the equivalent of 1 IU is 0.3 microgram (0.0003 mg) for vitamin A, 50 micrograms (0.05 mg) for vitamin C, 25 nanograms (0.000 025 mg) for vitamin D, and 2/3 milligram for (natural) vitamin E. Please note: for many substances there is no definite conversion between international units and mass units (such as milligrams). This is because preparations of those substances vary in activity, so that the effect per milligram of one preparation is different from that of another.
2006-09-27 03:00:48
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answer #1
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answered by Winza 2
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