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The dose (plural doses abbreviated  D ; of ancient Greek δόσις dose "gift", corresponding metered dosage amount ) designated in biology , medicine and pharmacy (usually small) quantity of a substance ( Pharmacology , Toxicology ), a pathogen ( infectious diseases ) or a radiation ( radiology , nuclear medicine , radiation therapy ), the one organism is supplied.


As a dosage , the dose is referred to a medicament , in the context of a therapy is to be administered. The effective dose (ED), also known as the effective dose , is that dose of an active ingredient which shows the desired therapeutic effectiveness in an individual . Their relationship is shown in a dose-effect curve . If the therapeutic efficacy is investigated on many individuals, the dose can be determined which produces the desired effect (e.g. a lowering of the arterial blood pressure to normal values) in 50% of the individuals . This dose is then called the ED 50 . Accordingly, the ED 95 is the dose that achieves the desired effect in 95% of the individuals. The NOEL indicates the highest dose with no effect. The NOAEL is the highest dose without side effects . The toxic dose range begins above this . The quotient of lethal dose and effective dose determines the therapeutic range of a drug . The equivalent dose is that dose of a drug that has the same effect as a specific dose of a similar drug.

Depending on the pharmacokinetic properties of a drug , the administered initial dose or loading dose is distributed in the various compartments of the organism ( blood , tissue, liquor, etc.). With the administration, the elimination of the drug also begins . In order to maintain a therapeutic concentration , a maintenance dose must therefore be applied continuously or at regular calculated intervals .

In the case of ongoing therapies, the amount is stated in the prescription practice over a time interval (example: 1500 mg amoxicillin daily in three individual doses for the treatment of tonsillar angina ). In some situations (e.g. with cytostatics or in pediatrics ) the dose is based on body weight or on the body surface .

A dose adjustment or a change in the time between the administration of individual doses ( dose interval ) may be necessary if a patient has disorders in the organ function that is necessary for the drug to be broken down or eliminated. Occasionally creeping in and creeping in is necessary to mitigate the effects of adding or removing a substance.


In toxicology and ecotoxicology , the toxicity of substances is determined in the course of a toxicity determination. In principle, a toxic effect can affect any organ system and, in the case of a pharmacological agent, must be distinguished from the desired effect. The toxic dose (TD) is the dose at which one or more toxic effects are produced. Since not all individuals react equally sensitively to toxic substances, the TD is usually linked to a number that indicates the percentage of individuals affected by a toxic effect. The TD 10 is the dose which triggers a toxic effect in 10% of the treated individuals (but not necessarily the same in all individuals). At TD 50 , half of the individuals treated are affected. As a dose lethal (LD or DL) is defined as the amount of material that the death of a living being leads. The size commonly used is the lethal dose 50% or the mean lethal dose (LD 50 or DL 50 ) at which half of a population of test organisms die. The lowest known toxic dose is below the TD 50 and the lowest known lethal dose is below the LD 50 .

The toxicity is usually dependent on the amount or the concentration of a substance and substances only develop their harmful effect when they reach the biological system in a sufficiently high amount. The quote from Paracelsus became popular for this realization : “All things are poison and nothing is without poison; the dose alone means that a thing is not a poison. B. Spinach is not dangerous, but if you eat 5 kg or more of it in a short time, it could lead to kidney damage . This principle also provides the basis for public health standards that define the maximum permissible concentrations of contamination in food , water and the environment . However, this principle can also cause misleading when used in a dirty way (the expression is also used very often in PR to show the effect of pollutants in products as low as possible). The relationship between dose and effect is not linear (one fifth of the dose does not necessarily have only one fifth of the effect) and differs depending on the chemical . Some substances have a significantly lower effect at a significantly lower dose (e.g. in the spinach example), while some mixtures still have similarly strong toxic effects even at a significantly lower dose. There are also some substances for which the principle does not apply and the effect differs completely depending on the dose (not just weaker or stronger).

In addition to the amount, the effect of the dose also depends on whether the corresponding dose is consumed once or over the long term (so that, for example, minor contamination in water and food can have greater chronic effects). These circumstances make it more difficult to correctly set limit values in environmental and health protection , since often only effects of a few doses are available.

Radiation protection

In radiation protection , the radiation dose describes the amount of ionizing radiation absorbed . Dose rate is the dose per unit of time (second, minute). The radiation dose is divided into ion dose , energy dose and kerma . The tolerance dose is the highest dose without irreparable damage.

Infectious diseases

In the case of pathogens , the infection dose describes the dose of pathogens administered in the event of an infection ; it can be above the minimum infection dose.

See also


Web links

Wiktionary: dose  - explanations of meanings, word origins, synonyms, translations

Individual evidence

  1. Duden - German universal dictionary . 6th, revised edition. Dudenverlag, Mannheim / Leipzig / Vienna / Zurich 2007 ( ).
  2. a b Lexicon of Biology . Elsevier Verlag, Volume 4: Cit-Elef, p. 361.
  3. The Dose Makes the Poison, Chemsafe Yale ( Memento October 10, 2014 in the Internet Archive )
  4. a b c d e Nancy Trautmann: The Dose Makes the Poison - Or Does It? Bioscience, 2005, American Institute of Biological Sciences.
  5. ^ Edward J. Calabrese: Hormesis: a revolution in toxicology, risk assessment and medicine. In: EMBO reports. 5, 2004, pp. S37-S40, doi: 10.1038 / sj.embor.7400222 , PMC 1299203 (free full text).