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Fei Lectures > L1: Fundamentalls Of Medicine Design > Flashcards

L1: Fundamentalls Of Medicine Design Flashcards

0
Q

Name the 3 types of dispersed system, classified by size of the dispersed particles?

A
  1. Molecular dispersion
  2. Colloidal dispersion
  3. Coarse dispersion
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1
Q

Define a disperse system

A

One component (dispersed phase) is dispersed (as particles or droplets) throughout another component (continuous phase).

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2
Q

If dispersed phase = solid, and continuous phase = solid, the disperse system is a……?

A

Solid suspension

Example: pigments in tablets

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3
Q

If dispersed phase = solid, and continuous phase = liquid, the disperse system is a……?

A

Liquid suspension, gel.

Jelly

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4
Q

If dispersed phase = solid, and continuous phase = gas, the disperse system is a……?

A

Solid aerosol

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5
Q

If dispersed phase = liquid, and continuous phase = solid, the disperse system is a……?

A

Solid emulsion

Cheese butter

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6
Q

If dispersed phase = liquid, and continuous phase = liquid, the disperse system is a……?

A

An emulsion.

Milk mayonnaise

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7
Q

If dispersed phase = liquid, and continuous phase = gas, the disperse system is a……?

A

Liquid aerosol.

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8
Q

If dispersed phase = gas, and continuous phase = solid, the disperse system is a……?

A

Solid foam.

Marshmallow

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9
Q

If dispersed phase = gas, and continuous phase = liquid, the disperse system is a……?

A

Foam.

Shaving

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10
Q

What are the particle sizes for a MOLECULAR dispersion?

A

Less than 1nm

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11
Q

What are the particle sizes for a COLLOIDAL dispersion?

A

Between 1nm-0.5um

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12
Q

What are the particle sizes for a COARSE dispersion?

A

Greater than 0.5um

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13
Q

Give examples of MOLECULAR dispersions

A

Oxygen molecules, ordinations

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14
Q

Give examples of COLLOIDAL dispersions

A

Cheese butter jelly milk shaving cream, natural and synthetic polymers

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15
Q

Give examples of COARSE dispersions

A

Most pharmaceutical emulsions and suspensions; red blood cells

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16
Q

Name the key characteristics of MOLECULAR dispersions (HINT: microscope, pass through, diffuse)

A
  • invisible in electron microscope
  • can pass through ultra filter, and semipermeable membrane
  • diffuse FAST
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17
Q

Name the key characteristics of COLLOIDAL dispersions (HINT: microscope, pass through, diffuse)

A
  • visible under ordinary microscope
  • pass through filter paper, do NOT pass thru semi permeable membrane
  • diffuse very slowly
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18
Q

Name the key characteristics of COARSE dispersions (HINT: microscope, pass through, dialyse, diffuse)

A
  • visible under microscope
  • do not pass through normal filter paper
  • do not dialyse thru semipermeable membrane
  • do not diffuse
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19
Q

Do the particles in a molecular dispersion diffuse fast or slow?

A

FAST

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20
Q

The particles in a MOLECULAR dispersion pass through semi permeable membrane and …..?

A

Ultra filter

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21
Q

Under which microscope is a MOLECULAR dispersion invisible? Electron/ ordinary?

A

Electron.

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22
Q

Particles in a COLLOIDAL dispersion diffuse very fast. T/F?

A

False. Particles in a COLLOIDAL dispersion diffuse very slowly.

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23
Q

Do the particles in a COLLOIDAL dispersion pass through filter paper? What else?

A

Yes, pass thru filter paper. Do NOT pass thru semi permeable.

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24
Q

Are particles in a COARSE dispersion visible under a microscope?

A

Yes, visible under microscope.

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25
Q

Can a COARSE dispersion diffuse?

A

NO.

26
Q

Why are dispersed systems used for pharmaceutical application? (3) reason 1

A 
- to increase the:
solubility,
Stability, 
Taste,
..of certain drugs in aqueous or oily preparations.
27
Q

Why are dispersed systems used for pharmaceutical application? Reason 2

A

To be used as drug delivery systems.

28
Q

What are the 2 types of COLLOIDAL systems?

A
  • Lyophilic colloids. (Solvent loving)

- Lyophobic colloids. (Solvent hating)

29
Q

How are lyophilic colloidal dispersions usually characterised?

A

There is a considerable affinity (how far they combine) between dispersion media and the SURFACE of the dispersed molecules.

30
Q

Name some LYOPHILIC colloids.

A

Organic molecules e.g. Gelatin, insulin, polystyrene

31
Q

In a LYOPHILIC colloidal system, if water is the dispersion medium, what dispersion will be formed?

A

A hydrophilic dispersion. (Hydration)

32
Q

In a LYOPHILIC colloidal system, if organic solvent is the dispersion medium, what dispersion will be formed?

A

A lipophilic dispersion.

33
Q

How are LYOPHOBIC colloids usually characterised?

A

There is little affinity (how far they combine) between dispersed phase and dispersion medium.

34
Q

Lyophobic colloids are thermodynamically unstable. What does this mean for the dispersed particles?

A

Their dispersed particles have a tendency to aggregate or coalescence. (Come together to form a whole).

35
Q

What are the 4 different pharmaceutical applications of suspensions?

A

Oral use

Topical application

Parenteral use

Inhalation

36
Q

Name an advantage for using suspensions? (P———–)

A

To improve palatability.

Property of being acceptable by mouth.

37
Q

Name an advantage for using suspensions? (It is e***)

A

It’s easier to take for people who have difficulty swallowing solid dosage forms e.g. Tablets

38
Q

Name an advantage for using suspensions? (Insoluble)

A

Can administer an insoluble drug as a liquid dosage form –> easier to take.

39
Q

Name an advantage for using suspensions? (Chemical ….)

A

Improved chemical stability.

40
Q

Name an advantage for using suspensions? (Bi**)

A

Improved bioavailability.

  • has a high surface area for it to dissolve faster.
  • faster onset of action than solid dosage forms.
41
Q

Name a disadvantage for using suspensions? (Re****)

A

The accuracy of dosage of suspensions is less reliable, compared to solutions.

42
Q

Name a disadvantage for using suspensions? (Cont—–)

A

Container:

  • bulky
  • difficult to transport
  • container more prone to damage
43
Q

Name a disadvantage for using suspensions? (Sto—-)

A

Storage: May lead to change in dispersion system e.g. Caking.

44
Q

Name a disadvantage for using suspensions? (Form—–)

A

Difficult to formulate e.g. Selecting acceptable suspending agents, wetting agents, preservatives.

45
Q

Name a disadvantage for using suspensions? (Manu——–)

A

Difficult to manufacture.

46
Q

Name the 3 different forms of stability of suspensions?

A

Chemical

Microbiological

Physical

47
Q

How is microbiological stability ensured within a suspension?

A

Preservatives used to prevent microbial contamination.

48
Q

What are the different physical factors of suspensions? (3)

A
  • flocculations/deflocculation
  • caking
  • particle growth (through dissolution and recrystallisation)
49
Q

What are the factors affecting the physical stability of a dispersed system? (3)

A
  1. Particle-Vehicle interactions
  2. Particle-Particle interactions
  3. Effect of vehicle on sedimentation
50
Q

What are the 2 main factors with particle vehicle interactions?

A
  • interfacial free energy

- wettability

51
Q

What are the 3 main factors with particle particle interactions?

A
  • electric double layer
  • electrical double layer interactions
  • flocculation and aggregation
52
Q

What happens if the attractive forces between the liquid and solid molecules > the forces between the liquid molecules themselves?

A

The liquid is able to wet the surface of the solid particles.

53
Q

What happens if the attractive forces between the liquid and solid molecules < the forces between the liquid molecules themselves?

A

The solid would clump on the surface of the liquid, and reform quickly after shaking.

54
Q

What is the wettability of drug particles?

A

Hydrophilic solids - easily wetted by water

Hydrophobic solids - repel water

55
Q

Name some examples of hydrophilic solids

A

Zinc oxide

Talc

Magnesium carbonate

56
Q

Name some examples of hydrophobic solids

A

Sulfur

Charcoal

57
Q

Majority of drugs in an aqueous suspension are ……..

A

Hydrophobic.

58
Q

How can the wettability of a drug solid surface be described?

A

By the contact angle.

59
Q

What is a contact angle?

A

The angle between a liquid droplet and the surface over which it is spread.

Can be between 0-180 degrees

60
Q

What are wetting agents?

A

They are surfactants.

61
Q

When dissolved in water, what does a wetting agent do?

A

It displaces the air phase around the particles surface and replaces it with a liquid phase.

62
Q

What does a wetting agent replace the air phase around the particles surface with?

A

A liquid phase.

63
Q

What is the purpose of a wetting agent?

A

It reduces the interfacial tension between solid particles and vehicle.

–> Lowers contact angle

–> improves dispersibility of the drug particles.

Fei Lectures (8 decks)

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