Brainscape's Knowledge GenomeTM

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


See full index

Yr 1 - Pharmacology > Absorption and Distribution > Flashcards

Absorption and Distribution Flashcards

1
Q

What are the 4 stages of pharmacokinetics?

A
  1. Absorption
  2. Distribution
  3. Metabolism
  4. Excretion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is absorption?

A

Transfer of the drug from site of administration into the general or systemic circulation

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

If drugs given orally are wanting to reach small intestine, how are they protected?

A

Bulking agents added

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

How does particle size affect absorption?

A

Has to breakdown into small enough particles to be absorbed via GI tract

If disintegrates slowly, the rate at which the drug is absorbed is limited by the rate of release and dissolution of drug from formulation

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

How much of drug needs to disintegrate in GI tract to form solution before becoming absorbed?

A

75%

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

How does formulation of particle affect absorption?

A

Has to be lipid soluble to be absorbed by gut (phospholipid bilayer)

Highly polar agents are absorbed slowly and incompletely

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

What do GI tract enzymes/acid aid in?

A

Breaking down drugs

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

How does slow motility of GI tract affect absorption?

A

Reduced absorption as takes long to reach SI

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

How does hypermotility / slow motility of GI tract affect absorption?

A

Hypermotility –> Bowels are moving excessively, reduced absorption, drug won’t be in bowels long enough

Slow motility –> Reduced absorption as takes long to reach SI

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

Do drugs have to be charged or uncharged to cross membrane?

A

Uncharged (and lipid soluble)

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

What is the degree of ionisation dependent on?

A

pH of their environment

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

What happens to drugs in stomach (ionisation wise)?

A

Stomach very acidic - acids become more ionised but bases become more unionised

Acids are proton donors, bases are proton acceptors

Basic drugs will cross membrane more easily than acidic ones in stomach

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

What happens to drugs in small intestine (ionisation wise)?

A

Acidic drugs cross membrane more easily than basic drugs

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

What happens to strong acids and bases in water?

A

Dissociate 100%

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

Why do you not need a higher dose for drugs delivered via injection?

A

Delivered straight into systemic circulation - bypasses liver (1st pass metabolism)

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

What is distribution?

A

The process by which the drug is transferred reversibly from one location to another within the body:
• From the general circulation into the tissues as concentrations in blood increase
• From the tissues into blood as blood concentrations decrease

17
Q

How does distribution mainly occur?

A

Mainly by passive diffusion of unionised form across cell membrane

18
Q

Describe conc after IV injection?

A

High plasma conc and drug rapidly equilibrates with well perfused tissue –> gives high conc in tissue

19
Q

What is the volume of distribution?

A

Theoretical volume that would be necessary to contain the total amount of an administered drug that it is observed in the blood plasma

If drug stays in plasma, its volume of distribution is smaller than if it is distributed widely in tissues (large volume = distributed to all tissues)

20
Q

What is the volume of distribution used to determine?

A
  • Used to determine the dose necessary for a desired blood concentration of a drug
  • Also used for estimating a blood concentration in the treatment of overdose
21
Q

What proteins act as drug carriers?

A

Albumins and glycoproteins (reversible)

22
Q

If a drug is bound/unbound to protein what are effects?

A

Bound –> inert
Unbound –> free to have effect

Plasma protein binding affects distribution

23
Q

What must drug bind to to have effect?

A

Right receptor in tissue

24
Q

How does regional blood flow affect distribution?

A

o If area is well perfused, more drug to region (liver, heart, kidney)
o Skin, skeletal muscle and fat are poorly perfused organs, drug needs to be given more often or for longer period of time to have effect here

25
Q

What does the administration of a drug that becomes highly bound to a patient who is already taking a drug that is highly protein bound cause?

A

Displacement of drug already bound which produces increased unbound concentration of drug and biological activity

26
Q

If a drug is widely distributed in tissues, how does the increase in unbound drug affect plasma conc?

A

The increase in unbound drug is rapidly redistributed to body tissues and unbound plasma concentration rapidly returns to negligible amount

27
Q

If a drug is only 20% bound (poorly albumin bound), what does a reduction of 5% in bound drug cause?

A

Unbound plasma concentration increases from 80% to 85% (negligible)

28
Q

If a drug is 95% bound (more strongly albumin bound), what does a reduction of 5% in bound drug cause?

A
  • Any changes in concentration has big effect, leads to side effe ts
  • Unbound plasma concentration increases from 5% to 10% (significant)
29
Q

When are changes in plasma protein binding significant?

A

Significant for drugs which are greater than 90% bound to plasma proteins

30
Q

What are cell membranes composed of?

A

Phospholipid bilayer

31
Q

What molecules can cross cell membranes?

A

Only those not bound to proteins

32
Q

How do molecules cross cell membranes by passive diffusion?

A

 Molecules move from area of high conc to low conc

 Ion channels may facilitate passive diffusion down conc gradient

33
Q

How do molecules cross cell membranes by facilitated diffusion?

A

 Molecules combine with membrane-bound carrier protein
 Movement still dependent on conc gradient
 Slightly faster than passive

34
Q

How do molecules cross cell membranes by active transport?

A

 Requires energy

 Molecule transported can be transported against conc gradient

35
Q

How do molecules cross cell membranes by pinocytosis?

A

 Compound engulfed by cell membrane and vesicle formed
 Vesicle taken into cell
- Molecule released

36
Q

How does absorption differ in children and elderly?

A

Children –> unreliable in neonates and greater transcutaneous absorption

Elderly –> in general unchanged

37
Q

How does distribution differ in children and elderly?

A

Children & Elderly –> fat components of body mass tends to be proportionately greater, acting as reservoir

Yr 1 - Pharmacology (10 decks)

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