Brainscape's Knowledge GenomeTM

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


See full index

DYS: Chemistry > Chemical basis of drug action > Flashcards

Chemical basis of drug action Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards Chemistry 101 flashcards Organic Chemistry 101 flashcards
1
Q

What is a buffer made up of?

A

Mixture of strong acid + weak base or weak acid + strong base

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

Buffer

A

Resist changes to pH on addition of further acid or base

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

What is a prodrug + give an example

A

Drug needs to be activated to become the active drug species

e.g. Omeprazole

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

Proton pump inhibitor

A

Inhibit proton pump in parietal cells

Binds irreversibly to the pump

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

Amphoteric H2 - receptor antagonist

A

Famotidine

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

Examples of H2 - receptor antagonist

A

Cimetidine
Ranitidine
Famotidine
Nizatidine

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

What is the acidity/basicity of H2RAs

A

Cimetidine, Ranitidine + Nizatidine = weakly basic

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

Journey of omeprazole

A

Stomach -=> duodenum => Blood => Parietal cells

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

Stability of omeprazole in acid

A

Unstable - it undergoes reaction to form prodrug and then binds irreversibly to proton pump

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

What produces urease enzyme

A

Helicobacter pylori

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

Function of urease enzyme

A

Protects bacterium from acid by producing NH3 which neutralises stomach acid

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

Similarities 13C + 12C

A

Naturally occuring

non-radioactive isotopes of carbon

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

Agonist at H2-receptor

A

Histamine

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

What is imidazole ring responsible for in H2RA

A

ADR

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

What is furan / thiazole ring responsible for in H2RA

A
  • increases selectivity + potency of antagonism at H2 receptors
  • reduces interaction with cytochrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does histamine stimulate

A
  • Acid secretion by parietal cells

- interacts with H2 receptors

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

When does the greatest secretion occur

A

Within 1 hour of eating

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

Acid secretion is _______ the volume of the meal

A

twice

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

What type of polymer is simeticone

A

Silicone polymer

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

Use of simeticone

A

Alters (lowers) surface tension of small bubbles + fuse them to form larger bubbles so gas in stomach can be easily lost
Relieves trapped wind

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

Calcium ions interact with _____________ and aid ___________ in the polymer

A

Alginate / alginic acid

Cross-linking

22
Q

How does alginic acid precipitate as a gel

A

When pH drops below 3.5

23
Q

What happens when alginic acid is a gel

A

It absorbs water and swells forming a raft

24
Q

Where is alginic acid extracted from

A

Brown seaweeds

25
Q

Examples of weakly basic drugs

A

Ranitidine, Cimetidine (H2RAs except Famotidine)

26
Q

Ionised species of weakly basic drugs will be…

A

Hydrated + more soluble

27
Q

Weak base HH-equation

A

pKa = pH + log BH+ / B

28
Q

Examples of weakly acidic drugs

A

Phenobarbital, phenytoin, Warfarin, NSAIDs

29
Q

Ionised species of weakly acidic drugs will be…

A

Hydrated + more soluble

30
Q

Weak acid HH-equation

A

pKa = pH + log HA / A-

31
Q

pKa of an acid is the pH at which it is…

A

Half dissociated

32
Q

Equation to calculate pH of a weak base

A

1/2pKw + 1/2pKa + 1/2logB

33
Q

Equation to calculate pH of a weak acid

A

pH = 1/2pKa - 1/2logHA

34
Q

Main active ingredients in raft forming medicines

A

Sodium alginate
Sodium bicarbonate
Calcium carbonate

35
Q

Source, structure + solubility of Alginic acid

A

From brown seaweeds
Polymer composed of sugar monomer units (mixture of polyuronic acids)
Molecular weight over 150,000 daltons
Insoluble in water

36
Q

Solubility of alginic acid + alginic salts

A

Alginic acid = insoluble

Alginate salt = water soluble

37
Q

Polyuronic acids composed of

A

D-mannuronic
L-guluronic acid
- responsible for solubility is COOH

38
Q

Mechanism by which alginic acid and alginate salts form a raft

A

If pH drops below 3.5 (approx. pka), alginic acid precipitates as a gel
Gel swells + absorbs water
Raft is formed

39
Q

Explain how + why carbon dioxide forms; in the creation + properties of raft

A

Many alginate based meds contain bicarbonate / carbonate

In acid:

  • bicarbonate/carbonate produce CO2
  • soluble alginate reacts to form insoluble alginic acid precipitate
  • gel traps CO2 gase, produce low density raft that can float on stomach contents
40
Q

Mechanism by which calcium affects structure + properties of raft

A

Calcium cations interact with alginate + aid cross linking in the polymer
Increases viscosity
- BP raft forming ability method = evidence that calcium cations increase raft strength

41
Q

Main active ingredient in anti-foaming agents

A

Simeticone

42
Q

Chemical + physical property simeticone (anti-foaming agent)

A

Dimethicone (polydimethylsiloxane) + silica (also activated dimethicone)
Silicone polymer
Alter (lower) surface tension of small gas bubbles so they fuse to form larger bubbles
Allows gas in stomach to be easily lost
It relieves trapped wind + bloating in dyspepsia (win-eze)

43
Q

Common active ingredients in antacid medicine

A 
Sodium bicarbonate 
Potassium bicarbonate
Calcium carbonate
Sodium carbonate
Magnesium carbonate 
Magnesium hydroxide
Aluminium hydroxide
44
Q

Heterocycle

A

Rings that contain carbon atoms and other non- carbon atoms

45
Q

mEq

A

(30 x Mhcl) - (Vnaoh x Mnaoh)
= amount consumed by medicine
= HCl - amt NaOH to reach pH 3.5
=mmol

46
Q

Ideal characteristics of an antacid

A
  • Acts locally - insoluble in water + not absorbed into circulation
  • pH of 3-5
  • exerts effects swiftly with good duration of action
  • does not produce large volumes of gas when reacting with HCl
  • not cause laxative effects/constipation
47
Q

Why is it advantageous to combine a number of antacids in one medicine

A
  • optimise rate of onset of action
  • duration of action
  • range of pH reached
  • moderate constipating + laxative effects
48
Q

What salts have constipating effects

A

Calcium + aluminium

49
Q

What salts have laxative effect

A

Magnesium

50
Q

Common chemical features in H2RA

A

Furan, thiazole + imidazole

51
Q

Common chemical features in NSAIDs

A

Benzene + Carboxylic group

52
Q

Chemical reaction + mechanism of the irreversible inhibition by aspirin

A

Nucleophilic substitution + addition-elimination reaction

  • transesterification

DYS: Chemistry (1 decks)

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