Pharmacodynamics

Front 1

Antagonist

Back 1

Drugs that decrease the actions of another drug or endogenous ligand; reverses or blocks the effect of an agonist and makes the agonist less potent; "blockers"; has no actions of its own and produces no efect by themselves; has no efficacy

Front 2

Competitive Antagonist

Back 2

Competes for the same binding sites as the agonist; can displace the agonist from the binding site if the affinity is > than the agonist; the agonist can reach 100% biological response if the agonists's concentration or affinity is sufficient; the duration of action is dependent on the 1/2 life
Example: Nalaxon vs. morphine

Front 3

Non-competitive Antagonist

Back 3

Permanently and strongly bind to a different receptor site than the agonist in order to reduce or block the effect of the agonist; the agonist will never reach 100% biological response; the Kd of the agonist will not change; the Emax decreases

Front 4

Allosteric Modulators

Back 4

Bind to a different receptor than the agonist and either inhibit or enhance the action of the agonist.

Front 5

Binding

Back 5

Causes: (1) Conformational change in the receptor which leads to immediate functional changes, (2) inhibition of action by covering an active receptor site, (3) Coupling (deals with tranduction) -- the drug produces a change in the receptor, the association with proteins results in the clinical effects; the physiologic and chemical processes that occur as a result of binding; it often occurs extra-cellularly -- the act of coupling allows extra-cellular messages to be transmitted to intracellular organelles which control cell function

Front 6

Pharmacology

Back 6

What the drug does to the body; including interaction @ the receptor sites and drug effects on the target organs.

Front 7

Efficacy

Back 7

The response produced by the drug.

Front 8

Maximum Efficacy

Back 8

The maximum response the drug illicits (when all the receptors are saturated)

Front 9

Potency

Back 9

The amount of drug given to produce a response

Front 10

ED50

Back 10

The dose required for 50% of people to exhibit the desired response.

Front 11

LD50

Back 11

The dose required for 50% of people to exhibit lethal effects.

Front 12

Therapeutic Index

Back 12

A crude measurement of drug safety based on animal toxicity data.

Front 13

Therapeutic Window

Back 13

The safe and effective dose range

Front 14

Affinity

Back 14

The degree of attraction that a drug has for the receptor site

Front 15

Kd

Back 15

The dissociation constant; a measure of affinity; indicates drug potency

Front 16

Emax

Back 16

The drug concentration that produces the maximal effect.

Front 17

EC50

Back 17

The drug concentration that produces 1/2 the maximal effect; EC50 = Kd

Front 18

Bioavailability

Back 18

The rate and extent to which a drug is absorbed or is otherwise available to the treatment site in the body.

Front 19

Receptor

Back 19

A protein molecule of the cell where binding occurs

Front 20

Agonist

Back 20

An exogenous or endogenous compound that binds to the receptor, causing a change in the receptor and resulting in a biological response

Front 21

Saturability

Back 21

A finite number of receptors on a cell; a filling up of receptors; maximal response when fully saturated.

Front 22

Simple Occupance Theory

Back 22

The maximal drug response when all receptors are occupied/saturated (after that point, increasing the drug concentration will not increase the response

Front 23

Reversibility

Back 23

The ability of the ligand receptor to associate and dissassociate

Front 24

Idiosyncratic Drug Response

Back 24

A response that is infrequently observed; often caused by genetic differences in drug metabolism or immunologic mechanisms.
Example: a drug is given with a resulting reaction in someone able to tolerate it previously

Front 25

Hyporeactive/Hyperreactive Responses

Back 25

Responses to a drug that are > or < than one would expect to see in the population.

Front 26

Tolerance

Back 26

A decrease in responsiveness of a drug over time.
Example: narcotic analgesics

Front 27

Tachyphylaxis

Back 27

A decrease in the responsiveness of a drug rapidly with continued administration.
Example: Transdermal NTG

Front 28

Homeostatic Reserve

Back 28

Modulation of the response by compensating for the drug's effect.
Example: The elderly have a decreased homeostatic reserve.

Front 29

Up-Regulation

Back 29

An increased number of receptors; occurs with the administration of an antagonist resulting in an increase in the total number of receptors; must be weaned slowly from the antagonist.
Example: A sudden discontinuing of beta-blockers results in rebound HTN due to large influx of agonist in increasing number of receptors

Front 30

Down-Regulation

Back 30

A decreased number of receptors from the administration of agonist decrease in coupling of receptors; is clinically seen as drug tolerance -- the client will require an increased dose of medication.