Brainscape's Knowledge GenomeTM

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


See full index

Clare's lectures semester 2 > Drug solubilisation 1 > Flashcards

Drug solubilisation 1 Flashcards

1
Q

what is a solution?

A
  • A system whereby the molecules of a solute e.g drug or protein are dissolved in a solvent vehicle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Just because something is insoluble in one vehicle does not mean that it is insoluble in everything vehicle. TRUE OR FALSE?

A

TRUE

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

Describe the three stages of solubilsation?

A
  • The solute or molecule comes out of crystal form
  • Cavity forms within the solute
  • The molecules then inserted inside the cavity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the factors affecting solubility of drugs in a formulation?

A
  • Nature of (organic/aqueous) solvent
  • Temperature
  • Size and shape of molecule
  • Molecular weight
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is polarity?

A
  • the seperation of an electric charge
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

with nature of solvent you need to consider polarity i.e like-dissolves like, non-polar solvents will dissolve non-polar solutes. TRUE OR FLASE?

A

TRUE

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

In order to be solvated within a given solvent, its molecules must first be able to be accommodated within the cavities between the solvent molecules. TRUE OR FALSE?

A

TRUE

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

With size and shape, decreasing particle size usually increases solubility. TRUE OR FALSE?

A

TRUE

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

There is a huge impact of drug shape and size on solubilisation. TRUE OR FALSE?

A

TRUE

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

How do you think the molecular weight can influence solubility and why?

A

Drugs with larger molecular weights are more difficult to solubilise because there are more solutes to be dissolved so require more solvents (particles more densely packed/ less freely movable)

  • It is difficult for solvent molecules to surround bigger molecules
  • Bigger molecules are generally more difficult to solubilise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Why does an increase in temperature lead to an increase in drug solubilisation?

A
  • Drugs molecules are able to move more freely, making them more like to fit into solvent caivites and hence solubilise
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what does the noyes-witney equation suggest?

A
  • It suggests that increasing surface area increases the drug rate of dissolution
  • Decreasing particle size increases surface area
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

If dissolution was rate limiting step in bioavailability then change in SA (or saturation solubility of the dissolution layer) will result in change in bioavailability. TRUE OR FALSE?

A

TRUE

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

what is partition coefficient of a molecule?

A
  • It is a measure of hydrophobicity of a molecule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

In solution drugs can partition between two immiscible solvents relative to their concentration and affinity for each phase. TRUE OR FALSE?

A

TRUE

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

what is partition coefficient useful for?

A
  • To estimate the distribution of drugs in different parts of the body
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Higher value P (logP), the greater the lipid solubility of the solute. TRUE OR FALSE?

A

TRUE

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

Drugs with higher log P have greater solubilisation issues. TREU OR FALSE?

A

TRUE

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

For intravenous applications, what factors do we need to consider?

A
  • Vehicle that is going to be used for administration e.g aqueous or organic
  • Anything viscous can lead to pain/toxic effects/blockage of veins – important to keep vehicle in aqueous phase (think of solubilisation)
  • Insoluble drugs need to be very stable before adminsitration
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

In order for drugs to be comfortably administered intravenously they must first be formulated into an aqueous based preparation. TRUE OR FALSE?

A

TRUE

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

For oral administration, what factors do we need to consider?

A
  • We need to think about advanced rechnology before administering
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

A drug with low solubility but high permeability can be a good potential for biological ativity. TRUE OR FLASE?

A

TRUE

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

In oral delivery drugs must first dissolve in the aqueous GI fluid of the stomach, before partitioning through the lipid biomembrane of the stomach lining and further onto its journey. TRUE OR FALSE?

A

TRUE

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

dissolution rate is often the rate limiting step for oral drugs. TRUE OR FALSE?

A

TRUE

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

what are the traditional excipients for drug solubilisation?

A
  • Surfactants
  • Co-solvents
  • microemulsions
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what are surfactants?

A
  • They are low molecular weight amphiphilic compounds
27
Q

surfactants have a hydrophobic tail and a hydrophilic head. TRUE OR FLASE?

A

TRUE

28
Q

what happens when surfactants are in a aqueous environemnt?

A
  • They form micelles (this is a type of intermolecular aggregation)
29
Q

what is the critical micellar concentration (CMC)?

A
  • It is the concentration above which micelles are formed in solution
30
Q

decreasing critical micellar concentration increases the stability of micelle because less surfactant is used. TRUE OR FALSE?

A

TRUE

31
Q

what factors affect CMC?

A
  • Temperature
  • Ph
  • Addition of electrolytes
  • structure and nature of hydrophobic group
32
Q

Hydrophobic drugs become encapsulated in the hydrophobic core of surfactant micelles. TRUE OR FALSE?

A

TRUE

33
Q

Micellar drug solubilisation
For drug delivery we can exploit this hydrophobic interaction, the hydrophobic core is shielding
Energetically more favourable (hydrophobic drugs) – can be exploited for drug delivery. TRUE OR FALSE?

A

TRUE

34
Q

Give examples of some commonly used surfactants?

A
  • Tween 80, span 80, SDS
35
Q

what are the disadvantages of surfactants?

A
  • Need high conc of CMC which can lead to instability
  • High excipients to drug ration which has low efficiency and can be expensive
  • High usage can lead to safety concerns
  • Oily solutions can cause discomfort especially with injections
36
Q

what are cosolvents?

A
  • Where drug solubility in one solvent is limited, the presence of two solvents employed
  • Two miscible solvents mixed, one is water and one is a solvent the drug dissolves readily in.
37
Q

why are co-solvents not prefered?

A
  • residual organic solvents can remain in the formulation which may be toxic to patients
38
Q

what are microemulsions?

A
  • A liquid mixture of oil, water and surfactants

- they are swollen micelle systems

39
Q

Microemulsions are thermodynamically stable. TRUE OR FLASE?

A

TRUE

40
Q

The microdroplet size formed in a microemulsion is usually less than 100 µm. true or false?

A

true

41
Q

what are the disads of microemulsions?

A
  • High excipient ot drug ratio (costly/side effects)
  • low stability
  • Low efficiency
42
Q

name some advaned technology for hydrophobic drugs solubilisation? (nanotechnology)

A
  • Liposomes
  • amphiphilic compounds
  • Cyclodextrins
43
Q

Advantages of nano sized drug delivery systems

A
  • At small size drugs can have unique physical and chemical properties
  • the large surface to volume ratio can make them ideal for specialisation
  • size, composition and physical properties can eb tailored
  • They can have intelligent properities due to their surface reactivity
44
Q

Nanoparticles injected systemically, can accumulate in the leaky microvasculature of tumour cells due the phenomenon known as the enhanced permeability and retention effect (EPR). TRUE OR FALSE?

A

TRUE

45
Q

what is the enhanced permeability and retention effect?

A
  • Nano size particles tend to bypass the tumour site – passive targeting / goes around circulation and accumulates around the tumour/ wont be spreading to healthy tissues
46
Q

what are liposomes?

A
  • Liposomes are closed spherical vesicles consisting of an aqueous core surrounded by one or more concentrically arranged bilayer membranes
47
Q

Liposomes are different from micelles, the drugs are inserted in the bilayer. TRUE OR FALSE?

A

TRUE

48
Q

Liposome vesicles are composed of unilamellar or multilamellar lipid bilayers. TRUE OR FALSE?

A

TRUE

49
Q

unilamellar liposomes are used in drug delivery. TRUE OR FLASE?

A

TRUE

50
Q

what is teh driving force for liposome formation?

A

-Driving force is interaction of aqueous regions and segregation of lipid regions from aqueous phase

51
Q

what is liposome formation dependent on?

A
  • Temperature
  • Lipid concentration
  • electrostatic interaction of polar lipids
52
Q

Shape of lipid is dependant on molecular shape of constituent amphiphiles. true or false?

A

true

53
Q

why are phospholipids used for liposome formation?

A
  • Low cost, neutral charge and inert nature
54
Q

As with surfactants the lipid head group determines the surface charge of the liposome. TRUE OR FALSE?

A

TRUE

55
Q

what is the most commonly used phospholipid for liposome formation?

A
  • Lecithin
56
Q

Liposomes are not that stable – cholesterol is inserted to make it more rigid, keeps liposomes together. TRUE OR FALSE? (reduces drug loss)

A

TRUE

57
Q

lipid tails determine the characteristics of liposome systems. TRUE OR FLASE/

A

TRUE

58
Q

Carbon chain length and degree of unsaturation influences the transition temperature of the lipid. TRUE OR FALSE?

A

TRUE

59
Q

Hydrophilic or hydrophobic drugs can become encapsulated inside the aqueous or lipid phase of the liposomes respectively. TRUE OR FALSE?

A

TRUE

60
Q

Liposomes can protect drug from degradation. TRUE OR FALSE?

A

TRUE

61
Q

Drug release rate from liposomes can be controlled via modification of bilayer composition. TRUE OR FALSE?

A

TRUE

62
Q

In general hydrophilic compounds are not well entrapped in liposomes compared to lipophilic compounds which are well retained in these drug carriers. TRUE OR FALSE?

A

TRUE

63
Q

what is the major diads for liposome as drug carriers?

A

Their major disadvantage as drug carriers is their instability on drug entrapment (inclusion of drug into lipid bilayer causes penetration → premature drug release).

  • poor stability is experienced on storing in aqueous phase
  • lipids are expensive

Clare's lectures semester 2 (10 decks)

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