Pharmacology definitions

Question 1

Pharmacodynamics is..

Are receptors important?

Answer 1

The action of the DRUG on the BODY. Receptors are KEY

Question 2

Maximum response by the drug is otherwise known as-

Answer 2

Emax

Question 3

EC50 is defined as…

Answer 3

The concentration of drug that produces 50% of the maximum effect.

Question 4

Difference between Bmax and Emax…

Answer 4

Emax is the maximum response by the drug, whereas Bmax is the maximum number of receptors bound to drug

Question 5

__ represents the concentration of free drug at which half maximal binding is observed. It characterises the receptor affinity for binding the drug in a reciprocol fashion.

Answer 5

Kd

Question 6

If Kd is low, binding affinity is___

Answer 6

High

Question 7

Define receptor-effector coupling

Answer 7

The process where the drug binds to receptor causing conformational changes and hence pharmacological response (ie coupling)

Question 8

Coupling efficiency is determined by 2 factors…

Answer 8

1. initial conformational change of the receptor

2. biochemical events that follow after coupling

Question 9

T or F. ion channels produce a non-linear coupling response

Answer 9

F- linear

Question 10

Drugs that bind to and mimic the regulartory effects of the endogenous signaling compounds are termed___

Answer 10

agonists

Question 11

____ agonists bind to a different region on the R

Answer 11

Allosteric.

Question 12

Difference between syntopic interaction, allosteric antagonism and chemical antagnoism and functional antagonism

Answer 12

Syntopic: competition with an agonist for the same or overlapping site on R
Allosteric: interacting with other sites on R
Chemical A: combining with the agonist to make it unavailable
Functional A: indirectly inibiting the cellular or physiological effects of the agonist

Question 13

Define partial agonist

Answer 13

Only partly as effective as agonists regardless of the concentration

Question 14

Define inverse agonists

Answer 14

drugs that stabilise receptors with background activity without an agonist, to render it inactive. Examples include: benzos, histamine, opioid, cannabinoid, dopamine, bradykinin, adenosine R.

Question 15

Examples of nuclear receptors/lipid soluble agents (3)

Answer 15

steroid receptors, vitamin D, thyroid hormone

Question 16

Tyrosine kinase receptor is an example of what class of physiological receptor

Answer 16

ligand regulated transmembrane enzyme

Question 17

Insulin, growth factor act on what type of physiological receptor?

1. GPCR
2. Nuclear receptor
3. TK transmembrane receptor
4. intracellular enzymes

Answer 17

3

Question 18

Define receptor down-regulation in TK receptors

Answer 18

Intensity and duration of actions of agents that act via TK receptors are limited by a process called receptor down regulation, where degradation of the TK-R occurs faster than the synthesis of the TK-R, hence the responsiveness to the ligands is diminished

Question 19

Examples of ligand-gated ion channels

Answer 19

nicotine, gabapentin

Question 20

Examples of voltage-gated ion channels

Answer 20

lidocaine, verapamil

Question 21

cGMP has an establised signalling role in what 2 areas?

Answer 21

Intestinal mucosa and vascular smooth muscle

Question 22

Define potency. Does it determine the clinical effectiveness or dose of a drug?

Answer 22

Concentration EC50 or dose ED50 required to produce 50% of drugs maximum effect.
Potency determines the DOSE.

Question 23

Maximal efficacy is defined as… and is limited by__

Answer 23

maximal response produced by the drug, and is limited by the drugs toxic effect

Question 24

__50 is defined as a dose at which 50% of individuals exihibit the specific quantal effect

Answer 24

ED 50- median effective dose

Question 25

Define LD50

Answer 25

Median lethal dose required at which 50% of individual die if given a specified dose

Question 26

Tolerance vs tachyphylaxis

Answer 26

Tolerance: responsiveness decreased with continued administration
Tachyphylaxis: responsiveness diminishes rapidly after given a drug

Question 27

What is the equation for Vd

Answer 27

Vd= amount of drug in body/Conc

Question 28

What is the equation for Clearance?

Answer 28

Cl= rate of elimination / Conc

Question 29

ETOH clearance is an example of __-order elimination

Answer 29

Zero order

Question 30

rate of drug elimination is directly proportional to the concentration= __-order elimination

Answer 30

First order

Question 31

Clearance= dose/AUC describes what order elimination?

Answer 31

First order

Question 32

When elimination becomes saturated and becomes constant despite increasing levels of drug concentration- this is called __-order elimination?

Answer 32

Zero order

Question 33

Rate of elimination = Vmax x c / Km+C
Describes what order elimination?
What does Vmax and Km stand for?

Answer 33

Zero order
Vmax: maximum elimination capacity
Km- when elimination is 50%

Question 34

Define half life

Answer 34

Time required to change the body concentration of drug by half during elimination
T1/2 = 0.7Vd / CL

Question 35

How many half lives does it take to eliminate 50% of the drug? How many half lives for 75%

Answer 35

1 half life; 2 half lives to eliminate 75%

Question 36

Describe what the AUC represents

Answer 36

AUC is proportional to the extent of bioavailability for a drug is its elimination is first order.

Question 37

Define first pass elimination

Answer 37

portal blood and metabolism by live/excretion into bile