Brainscape's Knowledge GenomeTM

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


See full index

Basic Pharmacology > BP 6 – Pharmacokinetics: Absorption and distribution > Flashcards

BP 6 – Pharmacokinetics: Absorption and distribution Flashcards

1
Q

Where do drugs accumulate?

A

In the fat/bone

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

How does the drug absorbed and cross through the cell membrane?

A 
Passive diffusion down concentration gradient - moves to the area with less drug concentration 
Active transport (especially GI tract) - selectively absorbed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What type of compounds are absorbed faster and more easily across cell membranes?

A

Lipid-soluble compounds (must be in solution)

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

How are drugs taken?

A

Enteral - oral route (stomach/SI), sublingual and rectal/vaginal

Parenteral - injection, IV, intramuscular, subcutaneous, transdermal, inhaled, intrathecal

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

Why is the stomach not an important site of absorption?

A

Many drugs are not absorbed here as has a low pH

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

What type of drugs are absorbed in the stomach?

A

Mainly weak acids

Small amounts of aspirin, NSAIDs and alcohol

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

What is the top and bottom of the stomach called?

A

Top - fundus

Bottom - pylorus

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

What are the layers of the stomach outer to inner?

A

Serosa, muscle layers, submucosa, mucosa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the pH from duodenum to terminal ileum?

A

pH 6 to 7.4

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

What type of drugs are absorbed in the SI?

A

Most weak bases

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

Why is the SI a good site of absorption?

A

Large, highly permeable, vascularised SA

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

What are the advantages of oral administration?

A

Safe, conventional and economical

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

What are the disadvantages of oral administration?

A
  • Irritant drugs cause sickness
  • Cannot give to vomiting patients
  • Some drugs destroyed by gut acid/flora
  • Intestinal absorption can be erratic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the factors affecting GI absorption?

A

Gut motility
Gut pH
Physio-chemial interactions
Partile size and formation

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

What antibiotic binds to Ca rich foods?

A

Tetracycline

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

Define bioavailability.

A

Fraction of administered drug dose that enters systemic circulation

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

Define first-pass metabolism.

A

In intestine and liver before drug reaches systemic circulation

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

What is the bioavailability for an iv dose?

A

1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the bioavailability fir an extra-vascular dose, e.g. oral?

A

<1

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

What are the limitations of bioavailability?

A

Each individuals enzyme activity, gastric pH, gut motility and does not consider the rate of absorption

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

When is sublingual administration used?

A

In cardiac patients, getting to ICA very fast

22
Q

What are the benefits of sublingual administration?

A

Fast response
Utilises venous drainage from the mouth to the superior vena cava
Avoids 1st pass metabolism

23
Q

Why is vaginal/rectal absorption used?

A

Bypasses the GI first pass effects
Rich blood supply
Absorption may be fast and extensive

24
Q

What is the pH for vaginal/rectal absorption?

A

pH 7-8

25
Q

What are the advantages clinically of vaginal/rectal absorption?

A

Useful when drug causes nausea and vomiting, or if the patient is already vomiting

26
Q

What are the rectum drainage?

A

Middle and inferior rectal veins go the systemic circulation

Superior rectal vein - is portal vein to the liver

27
Q

What are the advantages of intravenous injection?

A

Predictable, very rapid action
Alternative route for drugs which are irritant by (im)
Iv infusion for ill, hospitalised patients

28
Q

What are the disadvantages of intravenous injection?

A

Difficult /painful
Risk of infection
Cost and safety
Immediate adverse effects

29
Q

What is the advantage of subcutaneous or intramuscular injection?

A

Faster systemic effect than oral administration/ local effect

30
Q

What is an example of subcutaneous or intramuscular injection?

A

Local anaesthetic

31
Q

What are the important ways in which drugs cross cell membranes?

A

Passive diffusion through lipid
Diffusion through aqueous channel
Carrier mediated transport

32
Q

Do ionised or unionised substances have high lipid solubility?

A

Unionised

33
Q

Do ionised or unionised substances have low lipid solubility?

A

Ionised

34
Q

What does pKa measure?

A

Strength of acid/base

35
Q

If pH of solution = pKa of drug, what is said about the drugs ionisation?

A

The drug is 50% ionised

36
Q

Why can aspirin move across the cell membrane in the stomach?

A

Aspirin is mostly unionised (neutral)

Aspirin also has a pKa of 3.5

37
Q

What is drug distribution throughout the body dependent on?

A

Ability to cross the cell membranes - membrane permeability - lipid solubility
Blood flow into individuals - blood perfusion
Extent of its plasma protein binding
Tissue binding

38
Q

Why can the lungs and the liver get drugs rapidly distributed to them?

A

Tissues are well perfused

39
Q

What tissues are poorly perfused?

A

Fat, muscle and skin therefore the distribution rate is slower

40
Q

What tissues does drug distribution go through?

A

Blood vessel –> Interstitium –> Tissue cell

41
Q

When are drugs active, when they are free or plasma protein bound?

A

Free (unbound) drugs are active

42
Q

What does drug binding to plasma proteins depend on?

A

Concentration of free drug
Affinity for the binding sites
Concentration of plasma proteins

43
Q

What happens to the therapeutic effects if a drug is highly plasma protein bound?

A

Prolonged therapeutic effects and also slower acting

44
Q

Why does tetracycline accumulate slowly in bones and teeth?

A

Has a high affinity to calcium - therefore should not be used in children

45
Q

What is the calculation of the volume of distribution?

A

Total dose or drug in the body divided by the drug conc in plasma

46
Q

What shows a large volume of distribution?

A

Drugs accumulate outside the plasma in peripheral tissues e.g. stored in fat

47
Q

What shows a small volume of distribution?

A

Drugs confined to the plasma - are too large to cross the capillary wall easily

48
Q

What 2 key binding proteins are in the plasma? and where are they produced

A

Albumin
Alpha 1 acid glycoprotein

Produced in the liver

49
Q

What drugs bind to albumin?

A

Mostly basic and some neutral

50
Q

What drugs bind to alpha 1 acid glycoprotein?

A

Mostly acidic and some neutral

51
Q

When does albumin become depleted?

A

Malnutrition

Cirrhosis

52
Q

When does alpha 1 acid glycoprotein become elevated?

A

Acute phase protein, elevated in some diseases (cancer), inflammation

Basic Pharmacology (7 decks)

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