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Pharmacodynamics
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Pharmacodynamics studies what a drug does to the body: its effects on molecules, on the chemistry of cells and on how the body works. It is the counterpart of pharmacokinetics, which studies how the body handles that drug.
Every drug works because it acts on a target molecule and changes the way that molecule functions. One of those targets is the receptor, the site where another substance normally binds. Think of a lock. An agonist is a key that goes in and turns: it binds to the receptor and produces the same action as the substance that usually binds there. An antagonist is a key that goes in but does not turn: it binds to the receptor without activating it, and in doing so blocks it.
The response depends on how many receptors the drug occupies. The more it occupies, the greater the response, but it does not have to occupy them all to reach the maximal response.
In brief
Pharmacodynamics studies what a drug does to the body, its molecular, biochemical and physiological effects; pharmacokinetics studies how the body handles the drug.
Every drug changes how a target molecule works; when that target is a receptor, an agonist binds to it and produces the same action as the substance that normally occupies it, and an antagonist binds without activating it and blocks it.
The more receptors a drug occupies, the greater the response, although it does not have to occupy them all to reach the maximal response.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingPharmacodynamics, StatPearlsPublished
- National Cancer Institute, National Institutes of Healthagonist, NCI Dictionary of Cancer Terms
This page explains the topic in general terms; it does not tell anyone what treatment to follow.
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