Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS 242 - Core Phys/pharm > Pharmacokinetics II > Flashcards

Pharmacokinetics II Flashcards

1
Q

What are the 4 major water compartments in the body?

What percentages of the body weight do these conribute to?

A

1) Extracellular fluid
2) Intracellular fluid (20-40%)
3) Transcellular fluid (2.5%)
4) Fat (20%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does the volume of a compartment affect a drug?

A

Concentration of a drug in that compartment at equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What percentage do the water compartments contribute to the body weight?

A

50-70%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 3 components of extracellular fluid and how much body weight percentage?

A

1) Plasma (4.5%)
2) Interstitial fluid (30-40%)
3) Lymph (1-2%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is interstitial fluid?

A

Extracellular fluid which bathes cells and tissues

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

How are drugs distributed to different parts of the body?

A

In the plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Where is the bioavailability of a drug measured?

A

In the plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

How does fat impact the pharmacokinetics of a drug? (4)

A
  • Made of lipids
  • Non- polar drugs can easily enter and accumulate here
  • Poorly perfused
  • Varies between different people
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Examples of the compartments of the body which are tightly regulated and why(2)

A

The foetus
- Protected by the placenta

The CNS
- Protected by the BBB

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the distribution of the drug based upon?

A
  • Permeability

- Lipid solubility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the BBB impermeable to and why?

A

Water soluble molecules, they have poor lipid solubility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Examples of drugs which can’t cross the BBB?

A
  • Antibiotics
  • Chemotherapy drugs

(poor lipid solubility)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Examples of which molecules easily cross the BBB?

A

Lipid soluble

  • Ethanol
  • Caffeine
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What happens to tight junctions during inflammation?

A

Become ‘leaky’

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Where is the chemoreceptor zone in the body and what does this do?

A
  • Outside of the BBB

- Induces vomiting - can happen during drug treatments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does the protein albumin affect the free concentration of drugs in the plasma?

A
  • Binds to acidic drugs

- Reduces the concentration of drug in the plasma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 3 considerations of drug dose, regarding albumin?

A

When low doses of free drug are needed- need to increase dose to overcome binding to albumin

When high doses of free drug are needed - already taking a high dose
- Binding to and from albumin can decrease/increase the concentration of drug in the plasma - dangerous

Taking another drug can displace the original drug from albumin - increasing free concentration of the original drug

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How does the partition into body fat effect the free concentration of drug in compartments why is this a disadvantage?

A
  • Drug accumulates in the body fat
  • Changes the amount and duration of drug in the body
  • Difficult to predict the concentration of drug where you want it to act
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What drugs are more likely to partition into the body fat?

A

Lipid soluble drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What affects drug concentration in the body?

A

Absorption (permeability, lipid solubility, into fats)
Distribution
Metabolisation
Excretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Where does drug metabolism mostly occur?

A

In the liver

22
Q

What are the 2 biochemical reactions in the liver?

A

Phase 1 - catabolic reaction

Phase 2 - synthetic (anabolic) reactions

23
Q

What happens in phase 1 in the liver?

A
  • Produce more reactive compound
  • By oxidation, reduction or hydrolysis
  • Adds a reactive group (-OH) which serves as a point of attack for phase 2 reaction
24
Q

What happens in phase 2 in the liver?

A
  • Conjugation to produce an inactive product

-

25
Q

What is conjugation?

A

Attachment of a substituent group

26
Q

What are the microsomal enzymes present in the liver?(3)

A
  • Cytochrome P450
  • Alcohol dehydrogenase
  • MAO
27
Q

Where is cytochrome P450 found?

A

Embedded in the membrane of the smooth muscle endoplasmic reticulum of the liver

28
Q

Which enzyme can cause drug concentration to increase and why?

A

Alcohol dehydrogenase as it is easily saturated

29
Q

What does enzyme induction cause?

A
  • Increase metabolic enzyme in the body

- Cause drug to have a less effect as concentration decrease

30
Q

What does drug metabolism depend upon?

A

The ability of the drug to cross the membrane into the liver

31
Q

What are pro-drugs?

A

Drugs which only become active after undergoing phase 1 of metabolism

Drugs which concentrations rise slower in the body

32
Q

How do drugs get into the liver? (2)

A

Through the portal system

Through the plasma

33
Q

How may the metabolism of drugs decreased as they go through the portal system?

A

They join up with bile

34
Q

How do drugs escape metabolism? What happens instead?

A

They bind with food in the gut - go straight out of the body through excretion

35
Q

How is aspirin eliminated from the body?

A

Phase 1

  • Gain OH group
  • Make salicylic acid

Phase 2

  • Large sugar molecule added to the free -OH group
  • Forms glucuronide
  • Drug can no longer bind to target - drug action stopped
  • Facilitate excretion out of the body
36
Q

What is important about the intermediate of paracetamol when it is being metabolised?

A

It it poisonous

37
Q

Why is there differences between how individuals metabolise drugs?

A
  • Polymorphisms between individuals in P450 enzyme

- Different isoforms of P45 react with different drugs

38
Q

What are inducers of P450 drug metabolism?

A

Certain food activate/ inhibit P450

39
Q

What are the 3 routes of drug excretion from the body?

A

1) Renal excretion
2) GI excretion
3) Lung excretion

40
Q

When are drugs excreted in the urine?

A

After undergoing phase 2 of metabolism and after glomerular filtration etc. into the urine

41
Q

Which drugs go through urine excretion and which drugs don’t?

A

Small drugs do

Drugs bound to albumin don’t

42
Q

What happens if a person has kidney disease?

A

Concentration of drug in the blood may be higher

43
Q

What % of drugs are excreted through the kidneys?

A

80%

44
Q

What does the time course of clearance of a drug from the body follow and what is this?

A

Mono-exponential decay

45
Q

What does exponential decay depend upon?

A

Rate of metabolism and rate of excretion

46
Q

What is the half-life of a drug dependant on?

A
  • The concentration of drug taken

- The drug taken

47
Q

Describe saturation kinetics of a drug

A
  • Enzyme cannot keep up with the metabolism of the drug
  • When exceed the rate of which drug can be administered (set by the metabolism of the drug)
  • Linear increase in concentration of the drug in the plasma
  • Unexpected increase of the drug concentration causing toxicity
48
Q

What are some advantages of prodrugs? (4)

A
  • Prevent damage to the GI tract
  • Selective toxicity (eg. only cleaved in HIV cells)
  • Cross BBB quicker than active form
  • Greater bioavailability than active from
49
Q

What determines the rate of which a drug can be administered?

A

The metabolism of the drug

50
Q

Are strong bases absorbed well in the GI tract? Why?

A

NO

Favours dissociation of the drug - poor absorption

51
Q

What is sublingual administration?

What does this avoid?

A

Placing a tablet underneath the tongue

Avoids first pass metabolism in the liver

BMS 242 - Core Phys/pharm (13 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions