Pharmacodynamics Study Material - Key Terms and Definitions

Pharmacodynamics describes the relationship between the serum concentrations that determine the efficacy of the drug and the serum concentrations that ___

produce toxic effects

___ is a ligand that binds to and maximally activates a receptor

Agonist

___ is a ligand that binds to the same site and receptor as an agonist but only partially activates the receptor

Partial agonist

___ a ligand that binds to the same site and receptor as an agonist but induces a response opposite to that of an agonist

Inverse agonist

___ a ligand that only binds to a receptor but does not induce a response

antagonist

A partial agonist becomes an agonist in high concentrations because they ___

fill all receptors and agonists cannot bind

ED50 is the dose of a drug at which we get ___

50% of the drugs maximal response

If two drugs are compared, the drug with the lower ED50 is ___

more potent

2 multiple choice options

A drug must reach 50% of maximum response to be considered ___

potent

T/F: a partial agonist can be more potent than a full agonist?

True

1 multiple choice option

A steep slope on the DRC graph indicates that a small dose can produce ___

a big reponse

3 multiple choice options

Hydralazine is an example of a drug with a ___ DRC slope

steep

Thiazides are an example of a drug with a ___ DRC slope

flat

Are flat or steep DRC slopes more useful?

Flat - less dangerous

___ happens when the effects of two drugs are in the same direction and add up

Additive synergism

___ is when the effect of two drugs combined is greater than the individual effects of the components

Supraaditive syergism (potentation)

___ antagonism occurs when activated charcoal absorbs alkaloids and prevents their absorption into the blood stream

Physical

___ antagonism occurs when chelating agents inactivate ingested heavy metals

Chemical

___ antagonism occurs when histamine and epinephrine are given at the same time

physiological

___ antagonism occurs when an antagonist interferes with the binding of an agonist

Receptor

An anticholinergic will decrease intestinal spasms induced by cholinergic agonists but not the one induced by ___

histamine

___ antagonism can be both competitive and non-competitive

Receptor

Competitive antagonism reduces the ___ of an agonist whereas non-competitive antagonism reduces the ___ of an agonist

Potency, efficacy

1 multiple choice option

Competitive antagonism causes ___ of the DRC

a rightward shift

3 multiple choice options

Non-competitive antagonism causes ___ of the DRC

flattening

3 multiple choice options

Acetylcholine and atropine are an example of ___ antagonism

competitive

Diazepam and bicuculline are an example of ___ antagonism

non-competitive

The Quantal dose curve is a therapeutic index comparing ED50 to the ___

lethal or toxic dose 50

___ can be caused by an increase in drug metabolism, downregulation of receptors, or decrease in the number of receptors on the cell

Tolerance

___ refers to the rapid desensitization to a drug production by inoculation with a series of small frequent doses

Tachyphylaxis

Ephedrine, tyramine, and nicotine are examples of drugs that can cause ___

Tachyphylaxis

Upregulation is caused by an increase of receptors on a cell making the cells ___ to a hormone or drug

more sensitive

3 multiple choice options

A patient treated longterm with beta blockers will experience ___ of beta receptors

upregulation

A patient with elevated levels of insulin will experience ___ of insulin receptors

downregulation

Maximal drug response can be obtained at less than a maximal occupation of receptors when the effect of a drug persists ___

longer than the occupation itself

Maximal drug response can be obtained at less than a maximal occupation of receptors when the number of receptors ___

exceeds the number of drug molecules available

The presence of ___ increases sensitivity to the agonist

spare receptors