Brainscape's Knowledge GenomeTM

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


See full index

MD3002 - GI Pharmacology > Drug Absoprtion > Flashcards

Drug Absoprtion Flashcards

1
Q

What is bioavilability?

A

Fraction of unchanged drugs that reaches the systemic circulation

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

What gives 100% bioavaiability?

A

IV injection

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

What must generics have a bioaviability of?

A

must have a bioavailability of 80-125% compared to the reference product (EU regulation)

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

What is generic substiution?

A

occurs when a different formulation of the same drug is substituted. All generic versions of a drug are considered by the licensing authority to be equivalent to each other and to the originator drug

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

What is therapuetic substitution?

A

is the replacement of the originally prescribed drug with an alternative molecule with assumed equivalent therapeutic effect. The alternative drug may be within the same class of from another class with assumed therapeutic equivalence

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

What are the advantages of the oral route of administration of drugs?

A
  • cheap
  • safe
  • convienent
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the disadvantages of the oral route of drug administration?

A
  • patient compliance
  • variation in the bioaviability of the drug
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the main contributors to particle size and formulation of oral drugs?

A

Excipients, binding agents, lubricants and coatings

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

What are the 5 main oral routes?

A
  • Buccal/sublingual mucosa
  • Gastric mucosa
  • Small intestine
  • Large Intestine/colon
  • Rectal mucosa
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

describe the buccal/sublingual mucosa route

A
  • Direct absorption into blood stream
  • Avoids first pass metabolism
  • Not ideal surface for absorption
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How are drugs adapted to by-pass the gastric mucosa?

A

Enteric coating

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

What is the main site for drug absoprtion?

A
  • Small intestine
    • Main site of drug absorption
    • Large surface area, more neutral pH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How do drugs enter the systemic circualtion via the rectal mucosa?

A

Direct entry

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

What are the 4 ways small molecules cross the cell membrane?

A
  • Diffusing directly through the lipid
    • Lipid solubility highly important
  • Diffusing through aqueous pores
    • More likely important for diffusion of gases
  • Transmembrane carrier protein
    • E.g. solute carriers
  • Pinocytosis
    • Mostly macromolecules, not drugs
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 2 main methods that drugs cross cell membranes?

A
  • Diffusing directly through the lipid
    • Lipid solubility highly important
  • Transmembrane carrier protein
    • E.g. solute carriers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Describe the drug ionisation of weak bases

A
  • Ionised in acidic pH
  • Absorbed in small intestine
  • Ionisation in plasma?
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Describe the drug ionisation of weak acids

A
  • Unionised in acidic pH
  • BUT also absorbed in the small intestine
    • Large surface area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Draw the henderson-hasselbach for a weak base

A

compartment 1 = blood

compartment 2 = SI

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

Draw the henderson-hasselbach equation for a weak acid

A
20
Q

How does food affect the rate of gastri emptying?

A

generally slows rate

21
Q

What can cause decreased absoprtion?

A
  • intestinal motility
  • interactions with food, acids
  • presystemic metabolism
22
Q

What can cause delayed absoprtion?

A
  • gastric emptying
  • Cmax may be decreased
23
Q

What can cause increased absoprtion?

A
  • poorly water soluble drugs
    • increase solubilisation
    • decrease presystemic metabolism
24
Q

How do antacids and proton pump inhibitors affect absoprtion?

A

changes in gastric or intestinal pH

25
Q

How do Laxatives and anticholinergics alter absoprtion?

A

Changes in gastrointestinal motility

26
Q

How do vasodilators alter absoprtion?

A

changes in Gi perfusion

27
Q

How does neomycin alter absoprtion?

A

interference with mucosal function (decrease in SA)

28
Q

How do teracycline, calcium and magnesium alter absoprtion?

A

chelation (binding)

29
Q

How does cholestyramine alter absoprtion?

A

resin binding

30
Q

how does charcoal alter absoprtion?

A

adsoprtion

31
Q

What 2 diseases commonly affect GI motility?

A

Crohn’s and coeliac

32
Q

What are the main factors that affect oral absoprtion?

A
  • Particle size and formulation
  • GI motility
  • First pass metabolism
    • First pass metabolism by gut wall or hepatic enzymes
  • Physiochemical factors
    • Diet drug interactions, dietary factors, varying pH
  • Splanchnic blood flow
    • Increased flow increases drug absorption
  • Efflux pumps
    • P-glycoprotein
33
Q

Describe the subcutaneous route

A

Slow absorption due to blood flow

34
Q

Describe the intramuscular route

A
  • Lipophilic drugs rapidly
  • Polar drugs via bulk and endothelial cell junctions
  • High MWT or very lipophobic drugs via lymphatics
35
Q

Describe the rate of onset in parenteral routes

A
  • Extent of capillary perfusion
  • Drug vehicle
  • Affected by factors that alter perfusion
36
Q

What are the systemic effects of inhalation of drugs?

A
  • Lipid-soluble drugs
    • Volatile/gaseous anaesthetics
  • Drugs of abuse
  • Accidental poisoning
37
Q

What are the local effects of inhalation of drugs?

A
  • Modify structure (ipratropium)
  • Particulate size (salbutamol)
  • Selectively for receptors (salbutamol)
  • Rapid breakdown in circulation (fluticasone)
38
Q

What are the advanyahes of intranasal drugs?

A
  • Avoids hepatic first pass metabolism
  • Ease, convenience, safety
39
Q

What are the disadvantages of intranasal drugs?

A

Limited drugs suitable - Requires concentrated drug

40
Q

Describe healthy skin

A
  • Stratified, squamous epithelium
  • Keratinised layer
  • Sebaceous gland secretions
41
Q

What are the local effects of the topical route ?

A
  • Corticosteroids for eczema (hydrocortisone)
  • Antihistamines for insect bites (mepyramine)
  • Local anaesthetics (EMLA)
42
Q

What are the systemic effects of the topical route?

A
  • Transdermal patches (HRT, GTN, nicotine)
  • Accidental poisoning (AChEsterase insecticides)
43
Q

What must be closely checked when using the topical route?

A

surface area to volume ratio

44
Q

What are the key drug factors influencing route of administration?

A

lipid-solubility, weak acid/base, charge and size

45
Q

What are the key bioloigcal factors influencing drug absoprtion?

A

blood flow, surface area, metabolic enzymes and compartment pH

MD3002 - GI Pharmacology (4 decks)

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