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Pharmacokinetics
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Pharmacokinetics is the study of what the body does to a drug during the entire time the body is exposed to it. It differs from pharmacodynamics, which looks at the opposite: what the drug does to the body.
The drug's journey is studied in four processes. Absorption carries the drug into the systemic circulation, the blood that flows through the whole body. Distribution is how it spreads through the body. Metabolism transforms it into other compounds. And excretion removes it from the body. A pill's journey: getting in, spreading out, being transformed and leaving.
Most of that metabolism takes place in the liver, and it often turns the drug into a substance that dissolves more easily in water. That way it can be eliminated by the kidneys, which are the most common exit route.
In brief
Pharmacokinetics studies how the body interacts with an administered substance, such as a drug, over the entire exposure; pharmacodynamics, by contrast, examines the drug's effect on the body.
It generally examines four processes: absorption into the systemic circulation, distribution throughout the body, metabolism into other compounds, and excretion.
A pill's journey: getting in, spreading out, being transformed and leaving.
Most metabolism occurs in the liver and often makes the drug more water-soluble for elimination by the kidneys, the most common route of excretion.
Sources (1)
- National Center for Biotechnology Information, StatPearls PublishingPharmacokinetics, StatPearlsPublished
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