Pharmacology definitions Flashcards Preview

ACEM part 1 pharmacology > Pharmacology definitions > Flashcards

Flashcards in Pharmacology definitions Deck (37):
1

Pharmacodynamics is..
Are receptors important?

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

2

Maximum response by the drug is otherwise known as-

Emax

3

EC50 is defined as...

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

4

Difference between Bmax and Emax...

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

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.

Kd

6

If Kd is low, binding affinity is___

High

7

Define receptor-effector coupling

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

8

Coupling efficiency is determined by 2 factors...

1. initial conformational change of the receptor
2. biochemical events that follow after coupling

9

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

F- linear

10

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

agonists

11

____ agonists bind to a different region on the R

Allosteric.

12

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

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

13

Define partial agonist

Only partly as effective as agonists regardless of the concentration

14

Define inverse agonists

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

15

Examples of nuclear receptors/lipid soluble agents (3)

steroid receptors, vitamin D, thyroid hormone

16

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

ligand regulated transmembrane enzyme

17

Insulin, growth factor act on what type of physiological receptor?
1. GPCR
2. Nuclear receptor
3. TK transmembrane receptor
4. intracellular enzymes

3

18

Define receptor down-regulation in TK receptors

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

19

Examples of ligand-gated ion channels

nicotine, gabapentin

20

Examples of voltage-gated ion channels

lidocaine, verapamil

21

cGMP has an establised signalling role in what 2 areas?

Intestinal mucosa and vascular smooth muscle

22

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

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

23

Maximal efficacy is defined as... and is limited by__

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

24

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

ED 50- median effective dose

25

Define LD50

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

26

Tolerance vs tachyphylaxis

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

27

What is the equation for Vd

Vd= amount of drug in body/Conc

28

What is the equation for Clearance?

Cl= rate of elimination / Conc

29

ETOH clearance is an example of __-order elimination

Zero order

30

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

First order

31

Clearance= dose/AUC describes what order elimination?

First order

32

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

Zero order

33

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

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

34

Define half life

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

35

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

1 half life; 2 half lives to eliminate 75%

36

Describe what the AUC represents

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

37

Define first pass elimination

portal blood and metabolism by live/excretion into bile