Brainscape's Knowledge GenomeTM

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


See full index

Pharmacology, exam 1 > Pharmacokinetics I (Absorption & Distribution) > Flashcards

Pharmacokinetics I (Absorption & Distribution) Flashcards

1
Q

What is the ADME acronym?

A

Absorption
Distribution
Metabolism
Excretion

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

For most drugs, the concentration of drug at its site of action will be related to . . .

A

the concentration of drug in the systemic circulation

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

On what measurement does clinical pharmacokinetics heavily rely? Why?

A

Plasma drug concentrations, prediction of therapeutic and/or toxic effects of drugs

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

What is the therapeutic range on a concentration vs. time graph?

A

The area above the minimum effective concentration, but below the maximum tolerated concentration

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

Clinical significance of the AUC

A

Used to compare the amount of drug that reaches the systemic circulation by different routes of administration (bioavailability), as well as comparison of clearance between individuals given the same dose

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

What kind of relationship do clearance and AUC have?

A

Inverse

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

Definition of drug absorption

A

Processes by which drugs move from their site of administration to the plasma

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

Two processes of drug absorption following oral administration

A
  • Disintegration of solids and dissolution of drug in fluids of gastrointestinal tract
  • Passage of drug across or between cells to reach the systemic circulation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Seven factors affecting drug absorption

A
  1. Chemical composition of drug and delivery formulation
  2. Regional differences in blood flow
  3. Transport mechanisms
  4. Permeability characteristics
  5. Ion trapping
  6. Nonspecific binding
  7. Surface area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Describe aqueous diffusion

A

Small molecules

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

Describe lipid diffusion

A

Driven by concentration gradient, so the rate of absorption increases with increasing drug concentration. However, this may be limited if they are poorly soluble

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

How is lipid solubility affected? How is this predicted?

A

The degree of ionization; through the Henderson-Hasselbalch equation

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

Degree of ionization depends on what?

A

The difference between pH and pKa (0=50-50)

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

Weak bases are more concentrated in __ compartments

A

Acidic

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

Ion trapping

A

Phenomenon when acids/bases get “stuck” in different compartments on the opposite side of neutrality

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

Rate of drug absorption across membranes vs. surface area

A

Directly proportional

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

Where is the main site of absorption and why?

A

Has much higher surface area than the stomach

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

What is the rate limitation with active transport?

A

The process is saturable, and there may be competition for transporters between drugs and other drugs or endogenous substances

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

Most common route of enteral drug administration

A

Oral

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

Forms of oral drugs

A

Solutions, suspensions, capsules, tablets, etc.

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

Describe the first-pass effect

A

Some drugs are highly metabolized when they pass through the liver; only a fraction of the absorbed drug actually reaches systemic circulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Describe enterohepatic circulation and its consequences

A

Drugs may be secreted into the bile and reabsorbed via the intestine, which can delay delivery to circulation and reduce bioavailability

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What can affect rates of oral drug absorption?

A

Stomach contents, gastric emptying time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What may cause a drug to have less than 100% bioavailability?

A

Incomplete absorption, undergoing metabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Describe the salt factor

A

In rare cases, a drug may have a portion prepared as an inactive salt, so the dose may be adjusted similarly to bioavailability adjustments

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Advantages of sublingual drug administration

A

By-passes portal circulation, beneficial for absorption of more basic drugs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Disadvantages of sublingual drug administration

A

Taste and/or discomfort

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Buccal drug administration

A

Similar to sublingual

29
Q

Advantages to rectal drug administration

A
  1. 50-60% of absorbed drug by-passes portal circulation and therefore avoids first pass metabolism
  2. Useful in cases of nausea and vomiting
30
Q

Disadvantages to rectal drug administration

A

Discomfort, inconvenience

31
Q

Describe absorption by inhalation.

A

Passive diffusion, large surface area

32
Q

Common forms of drug inhalation

A

Volatile gasses and aerosol preparations

33
Q

What is a consideration for drug inhalation?

A

Absorption varies with depth and duration of inspiration, so it must be controlled by titration or metered inhaler

34
Q

Topical drug administration is usually used for __ therapy.

A

Local/non-systemic

35
Q

What form of topical drug can reach systemic circulation?

A

Highly lipid-soluble forms of drugs

36
Q

Common forms of topical drug administration

A 
Creams
Lotions
Gels
Ointments
Shampoos
37
Q

Transdermal drug administration

A

Reservoir in a patch has a drug that passively diffuses across the skin, which is driven by a concentration gradient

38
Q

What are the benefits of transdermal drug administration?

A

Controlled release of the drug into the patient, convenient, and bypasses GI tract

39
Q

What are the limitations/risks of transdermal drug administration?

A

Skin barrier limits the number of drugs that can be delivered by passive diffusion from an adhesive patch, and it could be irritating

40
Q

How is concentration gradient maintained in parenteral drug administration?

A

Blood flow to the area maintains it

41
Q

Advantages to parenteral drug administration

A

Greater degree of reliability and precision of administered dose, as well as fewer problems with absorption through the GI system

42
Q

Disadvantages to parenteral administration

A 
Sight of needle
Pain
Tissue damage/irritation
Drugs must be in solution
Limited volume
43
Q

Advantages of subcutaneous administration

A

Slow, even absorption and rate may be modified by altering blood flow (through temperature)

44
Q

Disadvantages of parenteral administration

A

Not effective when peripheral circulation is impaired, and there is a limited volume

45
Q

Advantages of intramuscular administration

A

More rapid absorption than subcutaneous administration, and blood flow can still be altered

46
Q

Disadvantages of IM administration

A

Potential for infection and nerve damage or inadvertent IV administration

47
Q

Advantages of IV administration

A

Fastest and most reliable means of achieving a defined blood level

48
Q

Disadvantages of IV administration

A

Risk of overdose by “bolus effect”

49
Q

Binding of acidic and basic drugs to plasma proteins

A

Acid drugs: albumin

Basic drugs: alpha-1 acid glycoprotein

50
Q

What happens when proteins are bound to the drug?

A

They are retained in the plasma

51
Q

One-compartment distribution

A

A rapid equilibrium is achieved between plasma and tissue distribution following drug administration, and declines mono-exponentially

52
Q

Two-compartment distribution

A

Rapid distribution to a central compartment (plasma) is followed by a slow distribution to other tissues/binding sites (second compartment). This results in a bi-exponential profile

53
Q

Volume of distribution is used to measure __

A

How evenly distributed a drug is in the body

54
Q

What is Vd?

A

A theoretical volume of fluid into which the total drug administered would have to be diluted to produce the concentration in plasma

55
Q

What two things does volume of distribution relate?

A

Relates dose to the initial plasma concentration of the drug at time = 0

56
Q

How is C0 calculated?

A

Monoexponential phase of decay is extrapolated backward to t = 0

57
Q

Large Vd is seen in what?

A

Drugs with a large fat and muscle distribution

58
Q

What happens to the volume of distribution with change in protein binding?

A

Increase in unbound drug will increase the apparent volume of distribution

59
Q

Plasma is _% of total body weight

A

5

60
Q

Interstitial fluid is _% of total body weight

A

16

61
Q

Intracellular fluid is _% of total body weight

A

35

62
Q

Transcellular fluid is _% of body weight

A

2

63
Q

Fat is _% of total body weight

A

20

64
Q

Pattern of distribution for lipid-insoluble drugs

A

Mainly confined to plasma and interstitial fluids; most do not enter the brain following acute dosing

65
Q

Pattern of distribution for lipid-soluble drugs

A

Can cross into any compartment, including crossing the the blood-brain barrier; may accumulate in fat

66
Q

What can happen with Vd with lipid-soluble drugs?

A

May exceed total body volume

67
Q

What class of drug can compete for protein binding?

A

Sulfonamides, which can increase the unbound fraction of other drugs

68
Q

Drug reservoirs

A

Fat and muscle. More drug can be stored in these than in systemic circulation; gradual release of drug from these sites can either prolong therapy or result in toxicity

Pharmacology, exam 1 (10 decks)

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