Pharmacodynamics & Drug Receptors

Question 1

Pharmacodynamics

Answer 1

effects of drugs on body

Question 2

Receptor

Answer 2

molecule to which a drug binds to bring about a change in function

Question 3

Receptor Site

Answer 3

specific region of the receptor molecule to which drug binds (site has high affinity for the drug)

Question 4

Inert Binding Molecule or Site

Answer 4

molecule to which a drug may bind without changing any function (binds but exerts no fxn, may keep other things from binding)

Question 5

Spare Receptor

Answer 5

receptor that doesnt bind drug when concentration is sufficient to produce max effect (max drug response from occupying less than half of the receptors)

Question 6

Effector

Answer 6

what accomplishes the final change, can be part of receptor molecule or a separate molecule

Ex: channel or enzyme molecule

Question 7

Emax (maximal efficacy)

Answer 7

max effect that can be achieved w/ particular drug regardless of dose

Question 8

Potency

Answer 8

amnt of drug needed to produce given effect, determined mainly by the affinity of the receptor for the drug, and number of receptors available

Question 9

Graded dose-response Curve

Answer 9

graph of increasing response to increasing drug conc.

Question 10

Quantal dose-response

Answer 10

graph of fraction of population that shows specified response at progresively increasing dose (used to determine how many ppl will be effected negatively from certain doses)

Question 11

EC50

Answer 11

CONCENTRATION that causes 50% of max effect or toxicity

Question 12

ED50

Answer 12

DOSE that causes 50% of max effect or toxicity

Question 13

TD50/TC50

Answer 13

median toxic dose/concentration at which toxicity occurs in 50% of cases

Question 14

LD50/LC50

Answer 14

median lethal dose required to kill half the members of a tested population

Question 15

Kd

Answer 15

concentration of a drug that binds 50% of receptors in the system

Question 16

Bmax

Answer 16

max number of receptors bound

Question 17

Agonist

Answer 17

ACTIVATES receptor upon BINDING

Question 18

Partial Agonist

Answer 18

drug that binds to receptor but produces smaller effect at full dosage than full agonist (will give partial result, not max effect)

Question 19

Allosteric Agonist

Answer 19

binds to receptor molecule w/out interfering w/normal agonist binding but alters response to normal agonist (binds to receptor, doesnt have effect nor does it interfere w/normal agonist binding but it will block the normal agonsits effect)

Question 20

Antagonist

Answer 20

binds WITHOUT activating its receptor, PREVENTS activation by agonist (can be overcome by giving AGONIST of higher conc.)

Question 21

Irreversible Antagonist

Answer 21

cannot be overcome by increasing AGONIST conc. its actions are irreversible (“destroys receptor”)

Question 22

Physiologic Antagonist

Answer 22

drug that counters effects of another drug by binding to a DIFFERENT receptor and causing OPPOSING effects

Question 23

Chemical Antagonist

Answer 23

drug that counters effects of another by binding the AGONIST DRUG (not receptor)

Question 24

Allosteric Antagonist

Answer 24

drug that binds to receptor molecule w.out interfering w/normal antagonist binding, but ALTERS THE RESPONSE TO THE NORMAL ANTAGONIST

Question 25

Therapeutic Index (TI)

Answer 25

relates dose of drug required to produce desired effect to dose that produces undesired effect

Narrow TI=range of best effect VERY close to range of toxic effect, dose careful, narrow window

Question 26

Signaling

Answer 26

once AGONIST drug has bound to receptor, some effector mechanism is activated

Question 27

5 Major Types of Transmembrane-signaling Mechanisms

Answer 27

Transmembrane Diffusion
Transmembrane Enzyme Receptors
Cytokine Receptors
Transmembrane Channels
G Protein Couples Receptors

Question 28

Transmembrane Diffusion

Answer 28

drug diffuses across membrane, and binds to an INTRACELLULAR receptor (drug tends to be lipid-soluble)

Question 29

Transmembrane Enzyme Receptors

Answer 29

drug effects MEMBRANE-SPANNING enzyme, binds outside of cell, signals through receptor to the inside of cell where process will occur

Question 30

Cytokine Receptors

Answer 30

drug binds outside cell, signals receptor, the receptor isnt necessarily doing the action, but it tells signal on inside (tyrosine kinase molecule JAK) to do the action (site acts as messenger)

the JAK’s are activated and phosphorylate STAT which travel to nucleus (effectors)

Question 31

Membrane Ion Channels

Answer 31

drug binds to receptor, receptor will open or close (directly cause opening of channel)

Drug can also modify channels response to another agent

the channel acts as both receptor and effector

Question 32

G Protein Coupled Receptors

Answer 32

drug cant directly bind to the effector, so it binds to receptor that is linked to effector.

receptor activates g-proteins–>stimulate/inhibit the effector

Question 33

Receptor Regulation

Answer 33

receptors are regulated by number, location & sensitivity.

Body can halt production of receptors if it thinks theres too many or it can make more if there arent enough

Question 34

Tachyphylaxis

Answer 34

acute decrease in response to a drug

frequent/continuous exposure to agonist, resulting in short-term reduction of receptor response

“overstimulate receptors until they are “numb”

somtimes can be overcome by increasing dose

Question 35

Downregulation

Answer 35

long term reduction in receptor # which occur in response to continuous exposure to AGONIST

(body feels like it doesnt need receptors so it stops producing them)

Question 36

Upregulation

Answer 36

increase in receptor # occurs when receptor activation is blocked by ANTAGONIST

body doesnt know receptors are blocked, thinks there arent enough receptors so it makes more

if pt were to DC a drug like this, they will have huge rebound effect becuase now there are even more receptors