Pharmacodynamics

thumb|400 px|Dose response curves of a full agonist, partial agonist, neutral antagonist, and inverse agonist An agonist is a chemical that activates a receptor to produce a biological response. Receptors are cellular proteins whose activation causes the cell to modify what it is currently doing. In contrast, an antagonist blocks the action of the agonist, while an inverse agonist causes an action opposite to that of the agonist.

thumb|Topics of pharmacodynamics Pharmacodynamics (PD) is the study of the biochemical and physiologic effects of drugs (especially pharmaceutical drugs). The effects can include those manifested within animals (including humans), microorganisms, or combinations of organisms (for example, infection).

class of pharmacological agents, which reduces or diminishes the effect of an agonist on a receptor

pharmacological concept describing subjects' reduced reaction to a drug following its repeated use

Tachyphylaxis (from Ancient Greek , 'rapid', and , 'protection') is a medical term describing an acute, sudden decrease in response to a drug after its administration (i.e., a rapid and short-term onset of drug tolerance). It can occur after an initial dose or after a series of small doses. Increasing the dose of the drug may be able to restore the original response.

description of effects of a drug on living things

agent in biochemistry

thumb|Graphical representation of the IC50 determination of the inhibition of an enzyme's activity by a small molecule ("drug"). Four different concentrations of the small molecule (ranging from 30 to 300 μM) were tested.

measure of drug activity

Efficacy is the ability to perform a task to a satisfactory or expected degree. The word comes from the same roots as effectiveness, and it has often been used synonymously, although in pharmacology a distinction is now often made between efficacy and effectiveness.

biochemical interaction through which a drug produces its pharmacological effect

change on an organism caused by differing levels of exposure (or doses) to a stressor after a certain exposure time

compound that binds to and activates a receptor with partial efficacy

right|thumb|400px|The tissue response (y-axis) to an agonist, in log concentration (x-axis), in the presence of different antagonist concentrations. The EC50 of the agonist is represented by the x co-ordinate that corresponds with the half-maximum of the leftmost curve. This is denoted by [A] Half maximal effective concentration (EC50) is a measure of the concentration of a drug, antibody or toxicant which induces a biological response halfway between the baseline and maximum after a specified exposure time. More simply, EC50 can be defined as the concentration required to obtain a 50% [...] e

category of drugs used to classify a drug according to certain criteria

type of drug

type of enzyme inhibition

substance that binds to and regulates the activity of chemical receptors

Pharmacometrics is a field of study of the methodology and application of models for disease and pharmacological measurement. It uses mathematical models of biology, pharmacology, disease, and physiology to describe and quantify interactions between xenobiotics and patients (human and non-human), including beneficial effects and adverse effects. It is normally applied to quantify drug, disease and trial information to aid efficient drug development, regulatory decisions and rational drug treatment in patients.

functional or anatomical change, at the cellular level, resulting from the exposure to a substance

form of the chemical element silicon

behaviour of substances

concept in biochemistry

agonist of some receptor subtype that's produced in the living organism, tissue or cell

pharmacologic characteristic

in medicine

alt=The figure shows the difference in action between an agonist and an antagonist, compared to native neurotransmitter function.|thumb|209x209px|Agonist vs. antagonist In pharmacology the term agonist-antagonist or mixed agonist/antagonist is used to refer to a drug which under some conditions behaves as an agonist (a substance that fully activates the receptor that it binds to) while under other conditions, behaves as an antagonist (a substance that binds to a receptor but does not activate and can block the activity of other agonists).

inability to tolerate the adverse effects of a drug

type of drug

agonistic activity of a given ligand relative to the activity of an endogenous agonist