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Flashcards in Pharmacology Deck (77):
1

Define pharmacodynamics

What a drug does to the body - biological affects and mechanism of action

2

Define pharmacokinetics

What the body does to a drug - absorption, distribution, metabolism and excretion

3

Define an agonist

A drug that binds to a receptor to produce a cellular response

4

Define an antagonist

A drug that blocks the action of an agonist

5

Define affinity

The strength of association between a ligand and receptor

6

Define efficacy

The ability of an agonist (not antagonist) to evoke a cellular response

7

Define competitive antagonism

When an agonist and antagonist both bind to the same orthosteric site

8

Define non-competitive antagonism

When an agonist and antagonist bind to different sites - the antagonist binds to an allosteric site

9

Which type of drugs readily cross the lipid bilayer?

Unionised ones

10

Which environments do acids dissociate more?

At high pH - acids donate protons, at high pH theres less H+ ions

11

Which environment makes it more likely for a base to remain basic?

At Low pH - bases accept protons and theres more protons available at a low pH

12

Define pKa

The pH at which 50% of a drug is ionised and 50% is unionised

13

What is oral availability?

The fraction of the drug that reaches the systemic circulation after ingestion

14

What is systemic availability?

The fraction of the drug that reaches the systemic circulation after absorption

15

What does the height of the Cm determine?

The rate of diffusion

16

What three factors affect drug absorption?

Solubility, chemical stability and lipid solubility

17

What happens to the conc. of H+ ions as the pH decreases?

H+ increases

18

Which pH do acids dissociate more in and why?

High pH - less H+ ions so they're easier to give away

19

Which pH do bases dissociate more in and why?

Low pH - there are more H+ ions so they are easier to accept

20

What is the henderson hasselbaclch equation?

pKa - pH = log [HA]/[A-]

21

what is oral availability?

The fraction of drug that reaches the systemic circulation after oral ingestion

22

What is systemic availability?

The fraction that reaches the systemic circulation after absorption

23

Which drugs move readily by diffusion?

Unionised ones

24

What is the equation for the volume of distribution?

Vd = dose/plasma concentration

25

Therapeutic ratio

TR = Maximum tolerated concentration/minimum effective concentration

26

How is the initial conc. of a drug calculated?

Co = Dose/ volume of distribution

27

what does doubling the dose do to a first order kinetic drug?

Doubles the duration of action but does not alter the half life

28

what does clearance determine?

The maintenance does rate - i.e. the does per unit time to maintain a steady plasma conc.

29

What does changing the rate of administration do in relation to steady state?

Alters the value of the steady state not how long it takes to get there

30

Xenobiotic

Foreign to the body

31

What does phase 1 of drug metabolism do?

Oxidise/reduce/hydrolysis = makes drug more polar

32

What does phase 2 of drug metabolism do?

Conjugates = adds an endogenous compound to increase polarity

33

Where are cytochrome proteins found?

In the ER of the liver

34

Which 3 cytochrome gene families are important in the liver?

CYP1, CYP2 and CYP3

35

What is step one in the monoocygenase P450 cycle?

Drug enters the cycle as a drug substrate

36

What is step two in the monoocygenase P450 cycle?

Molecular oxygen provides two atoms of oxygen

37

What is step three in the monoocygenase P450 cycle?

one atom of oxygen is aded to the drug to yield hydroxyl and the other forms water

38

What are the three processes in renal excretion?

Glomerular filtration
Active tubular secretion
Passive reabsorption by diffusion across the tubular epithelium

39

How are drugs which are highly protein bound secreted?

Via tubular secretion

40

What does an alkaline urinary pH do to the excretion of acids?

Increases excretion

41

What does an acidic urinary pH do to the excretion of bases?

Increases excretion

42

Depolarisation

The membrane potential becomes less negative

43

Hyperpolarisation

The membrane potential becomes more negative

44

Why does Na+ flow inward?

Both the conc. gradient and electrochemical gradient is inward

45

Why does K+ flow outward?

The conc. gradient is outward and the electrochemical gradient is inward however the conc. gradient is stronger

46

When are action potentials generated?

When threshold is reached

47

Which type of feedback is Na+ channels?

Positive

48

Which type of feedback is K+ channels?

Negative

49

Which state do Na+ channels have to be in to conduct?

Open state

50

Which state do Na+ channels have to be in to be non-conducting?

Inactive or closed state

51

Which cells are mylenating in the PNS?

Schwann cells

52

Which cells are mylenating in the CNS?

Oligodendrocytes

53

Which neurone is longest in the sympathetic division of the ANS?

Postganglionic

54

Which neurone is longest in the parasympathetic division of the CNS?

Preganglionic

55

What are the sympathetic neurotransmitters?

Pre - ACh
Post - NA

56

What is the parasympathetic neurotransmitter?

ACh - for pre and post

57

Sympathetic outflow?

Thoracolumbar T1-L2

58

Parasympathetic outflow?

Craniosacral outflow - CN III, VII, IX and X

59

Which receptors are activated in the sympathetic division?

G-protein coupled adrenoreceptors

60

Which receptors are activated in the parasympathetic division?

G-protein coupled muscarinic acetylcholine receptors

61

What kind of protein is the receptor of G-protein?

Integral membrane protein

62

What kind of protein is the G-protein?

Peripheral membrane protein

63

When there is no signalling what is bound to the G-protein?

GDP

64

When there is signalling what is bound to the G-protein?

GTP

65

Which part of the G-protein attaches to the signal molecule?

alpha

66

What acts as an enzyme to hydrolyse GTP to GDP?

alpha subunit

67

What substance converts ACh back into choline?

AChE

68

Parasympathetic receptors

M1- M3

69

What does M1 pair with and what is its action?

Gq - increases acid secretion in the stomach

70

What does M2 pair with and what is its action?

Gi - Decreases HR

71

What does M3 pair with and what is its action?

Gq - Bronchial contraction

72

Which substances are involved in the re-uptake of NA?

U1 and U2

73

What substances metabolise the NA once it has been taken back?

MAO (U1)
COMT (U2)

74

what does B1 pair with and what is its action?

Gs - Increased HR and force

75

What does B2 pair with and what is its action?

Gs - Bronchial relaxation and relaxation of vascular smooth muscle

76

What does a1 pair with and what is its function?

Gq - Contraction of vascular smooth muscle

77

What does a2 pair with and what is its function?

Gi - Inhibition of NA release