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Principles Of Pharmacology > Week 3 > Flashcards

Week 3 Flashcards

1
Q

What are the 2 different forms a drug can take in the body?

A

Free or bound

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2
Q

Where are free drugs present?

A

In the systemic circulation

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3
Q

What type of drugs can be moved out of the circulation for metabolism and excretion ?

A

Free

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4
Q

When do free drugs become stagnant and not have any real function?

A

When they have been moved into tissue reservoirs.

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5
Q

What are “bound drugs” bound to ?

A

Plasma proteins

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6
Q

Can bound drugs be moved out of the circulation for metabolism and excretion?

A

No

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7
Q

Which fluid compartment do bound drugs stay in?

A

Vascular

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8
Q

What is the ratio between the free and bound form of a drug in the body?

A

Equilibrium

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9
Q

What controls the amount of a drug in the body tat can be metabolised and excreted ?

A

The body’s affinity for tissue reservoirs and proteins

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10
Q

What are the 3 main categories of body water compartments ?

A

Vascular compartment.
Extra-cellular compartment.
Intracellular compartment.

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11
Q

What fluid types does the extra cellular compartment contain?

A

Interstitial fluid

Blood

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12
Q

How many litres of total body fluid does the blood plasma approximately take up?

A

3/4

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13
Q

How many litres of total bodying fluid does the interstitial fluid approximately take up?

A

11

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14
Q

Approximately how many litres of the total body fluid is taken up by intracellular fluid ?

A

28

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15
Q

What is the drug herapin used for?

A

Acts as an anticoagulant in the coagulation cascade.

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16
Q

Which fluid compartment does the drug herapin travel by?

A

Vascular

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17
Q

What is the drug aspirin used for?

A

Acts as an anticoagulant by reducing platelet plug formation.

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18
Q

What fluid compartments does Getamycin travel in ?

A

Vascular

Extra-cellular

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19
Q

What is Getamycin used for?

A

Is an antibiotic used for treating bacterial infections.

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20
Q

What fluid compartments of the body CNS ethanol travel via?

A

Vascular
Extra-cellular
Intra-cellular

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21
Q

What is the purpose of the drug warfarin?

A

It is an anticoagulant which prevents the production of coagulation factors by plasma proteins in the liver.

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22
Q

Why does warfarin take several days to become fully effective in the body?

A

It takes time for clotting factors which are circulating in the blood to be disintegrated and for the overall level of clotting factor in the blood plasma to be reduced.

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23
Q

What type of drugs are likely to be able to travel via all fluid compartments of the body?

A

Small, lipid-soluble drugs

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24
Q

What markers are often used to identify the blood plasma?

A

Evans blue

Inocyanine green

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25
Q

What markers are often used to identify the extra cellular fluid?

A

Insulin, raffinise, mannitol

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26
Q

What markers are often used to identify the intracellular fluid compartment of the body?

A

D20

Antipyring

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27
Q

What is the total volume of body fluid?

A

42 litres

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28
Q

Define ‘Volume of distribution’.

A

The volume of fluid required to contain the total amount of drug in the body at the same concentration that is present in the plasma.

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29
Q

How is volume of distribution calculated?

A

Dose / concentration of drug in plasma

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30
Q

What can be used to indicate how much of a drug has been stored in tissue reservoirs?

A

Volume of distribution value

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31
Q

What is indicated by a volume of distribution value that is greater than 42 litres?

A

The drug is being stored in tissue reservoirs and is no longer in the vascular component.

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32
Q

What does a greater volume of distribution indicated about the time taken to metabolism and excreted a drug?

A

Will take longer

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33
Q

What are the factors that affect volume of distribution?

A 
Plasma protein binding
Accumulation in fat
Tissue binding
Blood brain barrier
Placental barrier
Vascularity
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34
Q

What type of drugs bind to the plasma protein albumin?

A

Mainly acidic but some basic

35
Q

What is the most common plasma protein that drugs bind to ?

A

Albumin

36
Q

Give examples of drugs which bind to albumin.

A

Warfarin

Phenytoin

37
Q

What causes plasma albumin levels to reduce ?

A

Ageing

Liver problems

38
Q

What type of drugs bind to the plasma protein ‘ Alpha-1 avid glycoprotein’?

A

Basic drugs

39
Q

What are the issues with drugs binding to plasma proteins?

A

Some drugs may compete to bind to plasma proteins and therefore cause toxic effects.

40
Q

Outline how the binding of warfarin and aspirin to plasma proteins can lead to plasma toxicity.

A

Warfarin binds to plasma proteins. Aspirin displaces the warfarin.
Concentration of warfarin in the plasma rapidly increases.
Rapid increase in anti-coagulant effects.
Warfarin has a narrow therapeutic range so will soon reach toxic levels in the plasma.

41
Q

What type of drugs are most commonly distributed into the fat?

A

Lipid soluble drugs

42
Q

How fast do anaesthetics reach they’re desired location and why?

A

They reach the central nervous system very fast due to the high blood supply and cardiac output to this area.

43
Q

How quickly do anaesthetics reach an equilibrium of free and bound drugs in the CNS?

A

Rapidly due to the high blood flow and cardiac output in this area.

44
Q

How quickly do anaesthetics equilibrate in the adipose tissues and why?

A

Slowly, there is a low blood supply in this area.

45
Q

Why is it an issue that anaesthetics are released from the adipose tissue slowly?

A

The released anaesthetics will be re-distributed and have a longer lasting effect on the body than required.

46
Q

How does the amount of fat a person has affect volume of distribution?

A

The greater the adipose tissue (fat), the greater the volume of distribution.

47
Q

Where in the body does tetracycline bind to ?

A

Teeth and bones

48
Q

Where in the body does Chloroquine bind to ?

A

Liver, kidneys, lungs, spleen and melanin in the retina of the eyes.

49
Q

Describe complete capillaries.

A

Complete basal lamina

Continuous endothelial lining

50
Q

Describe fenestrated capillaries.

A

Complete basal lamina

Fenestrated endothelial lining

51
Q

Describe discontinuous capillaries.

A

Incomplete basal lamina

Fenestrated endothelial lining

52
Q

Where are continuous capillaries often found?

A

Fat, muscles, nervous system

53
Q

Where are fenestrated capillaries often found?

A

Intestinal villi, endocrine glands, kidney glomeruli

54
Q

Where are discontinuous capillaries often found?

A

Liver, bone marrow, spleen

55
Q

What type of capillaries are present in the blood Brain barrier?

A

Continuous

56
Q

Who theorised the blood brain barrier and how?

A

Paul Ehrlich - perfected by a student.
Came up with the magic bullet theory. Injected dyes into the bloody steam. These strained tissues in most organs except the brain.

57
Q

What is the main function of the blood brain barrier ?

A

To maintain homeostasis and composition of the brain.

Acts as a barrier against infection.

58
Q

What features of capillaries in the blood brain barrier aid it’s function?

A

Have Astrocytes which have foot processes that wrap around the capillaries and add another layer.

Have tight junctions between endothelial cells.

59
Q

What are Astrocytes?

A

Star shaped glial cells of the CNS

60
Q

What type of drugs have the ability to travel though the blood brain barrier?

A

Small, lipid-soluble

61
Q

What are often used to remove drugs from the brain?

A

Transporters such as glycoproteins.

62
Q

What is the placental barrier?

A

Several layers of cells separating the maternal and foetal circulation.

63
Q

What is a tetrogen?

A

A factor which causes embryonic abrnormalities.

64
Q

What is a phocomelia?

A

A drug which causes deformities of the limbs often being underdeveloped or missing

65
Q

Which entantiomer of thalidomide causes birth defects?

A

S

66
Q

What is Frances Kelsey famous for?

A

Reducing the distribution of thalidomide in the

U.S.

67
Q

What is alcohol foetal syndrome often characterised by?

A

Growth retardation
Developmental abnormalities
Cranial, facial and neural abnormalities

68
Q

Define drug administration.

A

Movement of a drug from the site of administration to the bloodstream.

69
Q

What factors affect drug absorption ?

A 
Metabolism (metabolic rate) 
Molecular size
Concentration gradient 
Surface area 
Route of administration
Dosage
70
Q

What properties of a drug are required for absorption?

A

Lipid solubility

Water solubility

71
Q

What is the partition coefficient of a drug?

A

The lipid concentration of a drug

72
Q

What does a drug having a high partition coefficient indicate?

A

It is highly lipid soluble.

73
Q

Give an example of a weakly acidic drug

A

Aspirin

74
Q

Give an example of a weakly basic drug.

A

Olanzapine

75
Q

How does the pH of the gastrointestinal tract affect drug absorption?

A

At a lower pH, there is a greater concentration of H+ ions, causing the solution to be more acidic and favour the absorption of weak acids. This is due to the deionisation of the drug when a H+ binds to an anion.

At a higher pH, there are less H+ and so the pH is greater. This facilitates absorption of weakly basic drugs. They become deionised when the carbon dissociates with H+

76
Q

What type of drugs do acidic solutions favour the absorption of ?

A

Weakly acidic

77
Q

What type of drugs do basic solutions favour the absorption of ?

A

Weak bases

78
Q

What happens to weakly acidic drugs when they are absorbed by an acidic solution?

A

They are deionised as a H+ binds to the anion

79
Q

What happens to weakly basic drugs when they are absorbed into a basic solution?

A

They dissociate a H ion

80
Q

What is bioavailability?

A

The proportion of a drugs dosage that is available to enter the systemic circulation

81
Q

What factors can reduce bioavailability?

A

First pass metabolism

82
Q

Name a drug which is subject to extensive first pass metabolism.

A

Lignocaine

83
Q

How can first pass metabolism be avoided or reduced?

A

Avoided using sublingual administration methods because it enters the capillaries under the tongue and surpasses the liver and gut.

84
Q

Explain what is meant by ‘plasma protein binding’ and what are the adverse effects it may cause on drug interaction.

A

Drugs which are bound to plasma proteins are unable to be removed via the circulation and excreted. This will mean that drug concentration is higher than required for longer than required so will move out of the therapeutic range and into the toxic range, leading to adverse effects. For example; acidic (and some basic) drugs frequently bind to Albumin in elderly people and in people with liver problems. This is exhibited by warfarin and phenytoin.

Principles Of Pharmacology (11 decks)

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