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Body and drug basics

Pharmacokinetics

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Pharmacokinetics is the study of what the body does to a substance, rather than what the substance does to the body. It covers four steps: getting in, spreading around, being broken down, and being removed. Every other entry in this group, from absorption through to clearance, is one piece of that picture.

Why it matters here

Records and product copy often quote a figure such as a half-life without saying which of the four steps it describes, or which species it was measured in. Having a name for the whole picture gives you somewhere to put such numbers and a reason to ask what exactly was measured.

What it is not

Not pharmacodynamics, the near-identical word for the opposite direction: what the substance does to the body, including receptor binding and the response that follows. Most of the confusion in this area comes from quoting a pharmacokinetic number as though it were evidence of an effect.

Also called

Usually shortened to PK, with pharmacodynamics shortened to PD. The four steps are often abbreviated ADME, for absorption, distribution, metabolism and excretion.

Compounds carrying this term

None on file yet. This term is in the controlled vocabulary but no compound record currently uses it — which is a statement about our coverage, not about the term.

See also