Pharmacodynamics
Definition:
Refers to what an administered drug does to alter the body’s physiological functions. It refers to the actions (beneficial or harmful) of the drug.
Relevance:
Pharmacodynamics (PD), the study of the actions of drugs in living organisms, informs their clinical applications, including their indications and predicted beneficial and adverse effects. The effects of a drug on the body can be described quantitatively, which is important to determine appropriate dose ranges. The dose-effect relationship, which is a core principle of pharmacodynamics, provides meaningful information to pharmacologists and clinicians. From this relationship, the median (mean) effective and toxic doses can be estimated, and the therapeutic safety as well as the therapeutic window can be determined. Moreover, the potency and efficacy of drugs can be compared.
The interaction between a drug and its molecular target underpins the molecular mechanisms of drug actions and how drugs affect cellular function. Changes in cellular function are translated into changes in tissues and organ function, which affect the systems connected to these organs. These changes are perceived by the patient as symptom improvement or relief and/or toxicity (side effects). Thus, PD underpins therapeutics.
Teaching tips:
This is a very rich topic to teach! Here are some good topics to cover when teaching pharmacodynamics:
Linked terms: therapeutics, pharmacokinetics, receptor, dose response curve
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