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Pharmaceutics Spring 2016 > Dispersed Systems > Flashcards

Dispersed Systems Flashcards

1
Q

dispersed system

A

fine particles, evenly distributed in a vehicle/dispersion medium

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2
Q

T/F In a dispersion system, the particles are NOT aggregated

A

FALSE; are

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3
Q

What are the 3 types of dispersion systems?

A
  • molecular dispersion
  • colloidal dispersion
  • coarse dispersion
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4
Q

dispersion system?

  • true solution
  • less than 1 nm
A

molecular dispersion

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5
Q

dispersion system?

  • generally can not be seen with the eye
  • 1 nm- 0.5 um
A

colloidal dispersion

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6
Q

dispersion system?

  • BIG
  • greater than 0.5 um
A

coarse dispersion

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7
Q

In dialysis, the blood cells and plasma proteins fall in the ____ size and will be retained

A

colloidal

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8
Q

What are the 3 types of colloidal systems?

A
  • lyophilic system
  • lyophobic system
  • association/amphiphilic colloid
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9
Q

lyophilic system

A

loves the solvent (example water)

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10
Q

lyophobic system

A

need special dispersion or condensation method

-dislikes solvent

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11
Q

surfactants are an example of ____ colloids

A

association/ amphiphilic

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12
Q

surfactant (2)

A
  • lowers the surface tension

- have a certain affinity for both polar and non polar solvents (does not allow water and oil to separate)

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13
Q

at a concentration that is characteristic of each amphiphile, these molecules will aggregate to produce____

A

micelles (hydrophilic on the outside and lipophilic on the inside)

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14
Q

CMC?

A

critical micelle concentration

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15
Q

Critical Micelle concentration involves….

A

blocking the surface and adding surfactant passed the concentration leading to a micelle being formed

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16
Q

Colloids have properties such as ____, _____, and _____

A

optical
kinetic
electrical

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17
Q

What is an example of a natural colloid?

A

protein

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18
Q

What is an example of a coarse dispersion?

A

suspension

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19
Q

T/F Suspension may be for oral, ophthalmic, parenteral, or topical use

A

TRUE

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20
Q

advantages of suspension (4)

A
  • greater flexibility in the administration
  • can better mask the taste of the drug
  • some drugs are more stable as a suspension
  • drugs not soluble in common vehicles
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21
Q

What are the 3 desired features of a suspension?

A
  • pour readily and evenly
  • particle size should remain constant
  • uniform dispersion/ settle slow
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22
Q

T/F The bigger the particle, the better it dissolves

A

TRUE

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23
Q

Stoke’s law

A

factors involved in the rate of velocity of SETTLING of the particles in a suspension

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24
Q

T/F Stokes equation applies to uniform, perfectly spherical particles settling in a very dilute suspension WITH hindrance or turbulance

A

False; without

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25
Q

What are ways to slow settling in a suspension? (3)

A
  • small particle size
  • increase density of vehicle
  • increase viscosity of vehicle
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26
Q

How can particles dispersed in a liquid media become charged? (2)

A
  • selective adsorption of ionic species present in solution

- ionization of groups situated at the surface of the particle

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27
Q

The electrical double layer is known as the …..

A

Nernst and Zeta potential

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28
Q

T/F There is ALMOST ALWAYS charges surrounded by particle size particles in a suspension

A

TRUE

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29
Q

11’ is known as

A

nernst potential : true potential

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30
Q

22’ is known as

A

electrokinetic: zeta potential

31
Q

What is the goal for sedimentation volume?

A

to be close to 1

32
Q

What is a disadvantage of deflocculated suspensions?flocculated suspensions?

A

deflocculated: caking
flocculated: high sedimentation–>loose aggregation

33
Q

_____ follows Stoke’s law

A

deflocculated suspension

34
Q

What is the first step when formulating a suspension?

A

wetting: disperse particles in a medium and make sure they sink

35
Q

Second step for the formulation of a suspension is? (3)

A
  • deflocculated suspension in structured vehicle
  • flocculated suspension
  • flocculated suspension in structure vehicle
36
Q

What is the purpose of a structured vehicle?

A

increase viscosity (thickness)

37
Q

______- act as flocculating agents by reducing the zeta potential between particles

A

electrolytes

38
Q

_____ is an excipient used to increase viscosity

A

sodium CMC (carboxyl methyl cellulose)

39
Q

When should a flocculated suspension in a structured vehicle be used?

A

when V is less than 1

40
Q

What are some examples of suspension? (3)

A
  • antacid
  • antibiotics
  • parenteral penicillin
41
Q

What is the typical formula for a suspension? (5)

A
  • drug
  • wetting agent
  • buffer
  • preservative
  • suspending agent
42
Q

What is a common wetting agent used?

A

polysorbate 80

43
Q

The purpose of suspending agents is to……

A

increase viscosity

44
Q

Neonatal formulations should NOT contain (4)

A
  • preservatives
  • colorings
  • flavoring
  • alcohol
45
Q

_______ two immiscible liquid phases, one of which is dispersed as globules

A

emulsion (oil in water or water in oil)

46
Q

dispersed phase: _______: continuous phase: ______

A

inside; outside

47
Q

T/F Reduced globule size are more effective

A

TRUE

48
Q

T/F Oil in water is NOT a convenient way of oral administration

A

FALSE: IS

49
Q

Classifications of surfactants (wetting agent) (4)

A
  • anionic
  • cationic
  • amphoteric
  • nonionic (THE BEST–>less toxic)
50
Q

HLB (Hydrophilic Lipophilic balance) is used to classify

A

surfactants on a scale of 0-18

51
Q 
HLB: 
High Number (HLB 9-12)? Low Number (HLB 3-6)?
A

hydrophilic; lipophilic

52
Q

T/F HLBs are additive

A

TRUE

53
Q

If the emulsion is thermodynamically unstable then…..

A

an emulsifying agent is necessary

54
Q

The phase in which more soluble becomes the _____ phase

A

continuous

55
Q

referred to as the 4:2:1 method because for every 4 parts by volume of oil, 2 parts of water and 1 part of gum are added in preparing the initial or primary emulsion

A

continental or dry gum method

56
Q

the same proportions of oil, water, and gum are used as in the continental or dry gum method, but the order of mixing is different, and the proportion of ingredients may be varied

A

english or wet gum method

57
Q

useful for the extem- poraneous preparation of emulsions from volatile oils or oleaginous substances of low viscosities

A

bottle or forbes bottle method

58
Q

___ is when oil droplets rise to the top

A

creaming

59
Q

What is a problem seen in emulsions?

A

aggregation and coalescence (separation of emulsion)

60
Q

phase-volume ratio of emulsion

A

how much is oil and how much is water

61
Q

if a preservative is added into an emulsion what may happen?

A

incompatibility due to the preservative having a charge

62
Q

multiple emulsion

A

an emulsion inside an emulsion

63
Q

microemulsion

A

in addition to the surfactant there is also a cosurfactant

64
Q

examples of emulsions (3)

A
  • mineral oil (lubricating cathartic)
  • castor oil (laxative)
  • simethicone (antiflatuent)
65
Q

deformation and the flow of matter

A

rheology

66
Q

The simplest flow you can get is an _____ flow, which is seen in solutions

A

newtonian (always start from the origin)

67
Q

T/F The rate of shear is DIRECTLY proportional to the shearing stress

A

TRUE

68
Q

-plastic
-pseudoplastic
-dilatant
are examples of?

A

non-newtonian rheological flow materials

69
Q

_______ does not begin to flow until the shearing stress exceeds the yield value

A

plastic flow

70
Q

_____ curve begins at origin but no part of the curve is linear

A

pseudoplastic flow (No e value)

71
Q

stress can cause a breakdown of structure that does not reform immediately when the stress is removed

A

thixotropy

72
Q

Mechanical properties of materials that exhibit both viscous properties of liquids and elastic properties of solids

A

viscoelasticity

73
Q

behavior of blood, mucus, synovial fluid

A

biorheology

74
Q

____ has pronounced pseduoplasicity and thixotropy

A

mucus

Pharmaceutics Spring 2016 (20 decks)

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