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Pharmaceutics Spring 2016 > Dispersed Systems > Flashcards

Flashcards in Dispersed Systems Deck (74)
1

dispersed system

fine particles, evenly distributed in a vehicle/dispersion medium

2

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

FALSE; are

3

What are the 3 types of dispersion systems?

-molecular dispersion
-colloidal dispersion
-coarse dispersion

4

dispersion system?
-true solution
-less than 1 nm

molecular dispersion

5

dispersion system?
-generally can not be seen with the eye
-1 nm- 0.5 um

colloidal dispersion

6

dispersion system?
-BIG
-greater than 0.5 um

coarse dispersion

7

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

colloidal

8

What are the 3 types of colloidal systems?

-lyophilic system
-lyophobic system
-association/amphiphilic colloid

9

lyophilic system

loves the solvent (example water)

10

lyophobic system

need special dispersion or condensation method
-dislikes solvent

11

surfactants are an example of ____ colloids

association/ amphiphilic

12

surfactant (2)

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

13

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

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

14

CMC?

critical micelle concentration

15

Critical Micelle concentration involves....

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

16

Colloids have properties such as ____, _____, and _____

optical
kinetic
electrical

17

What is an example of a natural colloid?

protein

18

What is an example of a coarse dispersion?

suspension

19

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

TRUE

20

advantages of suspension (4)

-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

21

What are the 3 desired features of a suspension?

-pour readily and evenly
-particle size should remain constant
-uniform dispersion/ settle slow

22

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

TRUE

23

Stoke's law

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

24

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

False; without

25

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

-small particle size
-increase density of vehicle
-increase viscosity of vehicle

26

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

-selective adsorption of ionic species present in solution
-ionization of groups situated at the surface of the particle

27

The electrical double layer is known as the .....

Nernst and Zeta potential

28

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

TRUE

29

11' is known as

nernst potential : true potential

30

22' is known as

electrokinetic: zeta potential

31

What is the goal for sedimentation volume?

to be close to 1

32

What is a disadvantage of deflocculated suspensions?flocculated suspensions?

deflocculated:caking
flocculated: high sedimentation-->loose aggregation

33

_____ follows Stoke's law

deflocculated suspension

34

What is the first step when formulating a suspension?

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

35

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

-deflocculated suspension in structured vehicle
-flocculated suspension
-flocculated suspension in structure vehicle

36

What is the purpose of a structured vehicle?

increase viscosity (thickness)

37

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

electrolytes

38

_____ is an excipient used to increase viscosity

sodium CMC (carboxyl methyl cellulose)

39

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

when V is less than 1

40

What are some examples of suspension? (3)

-antacid
-antibiotics
-parenteral penicillin

41

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

-drug
-wetting agent
-buffer
-preservative
-suspending agent

42

What is a common wetting agent used?

polysorbate 80

43

The purpose of suspending agents is to......

increase viscosity

44

Neonatal formulations should NOT contain (4)

-preservatives
-colorings
-flavoring
-alcohol

45

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

emulsion (oil in water or water in oil)

46

dispersed phase: _______: continuous phase: ______

inside; outside

47

T/F Reduced globule size are more effective

TRUE

48

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

FALSE: IS

49

Classifications of surfactants (wetting agent) (4)

-anionic
-cationic
-amphoteric
-nonionic (THE BEST-->less toxic)

50

HLB (Hydrophilic Lipophilic balance) is used to classify

surfactants on a scale of 0-18

51

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

hydrophilic; lipophilic

52

T/F HLBs are additive

TRUE

53

If the emulsion is thermodynamically unstable then.....

an emulsifying agent is necessary

54

The phase in which more soluble becomes the _____ phase

continuous

55

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

continental or dry gum method

56

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

english or wet gum method

57

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

bottle or forbes bottle method

58

___ is when oil droplets rise to the top

creaming

59

What is a problem seen in emulsions?

aggregation and coalescence (separation of emulsion)

60

phase-volume ratio of emulsion

how much is oil and how much is water

61

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

incompatibility due to the preservative having a charge

62

multiple emulsion

an emulsion inside an emulsion

63

microemulsion

in addition to the surfactant there is also a cosurfactant

64

examples of emulsions (3)

-mineral oil (lubricating cathartic)
-castor oil (laxative)
-simethicone (antiflatuent)

65

deformation and the flow of matter

rheology

66

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

newtonian (always start from the origin)

67

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

TRUE

68

-plastic
-pseudoplastic
-dilatant
are examples of?

non-newtonian rheological flow materials

69

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

plastic flow

70

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

pseudoplastic flow (No e value)

71

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

thixotropy

72

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

viscoelasticity

73

behavior of blood, mucus, synovial fluid

biorheology

74

____ has pronounced pseduoplasicity and thixotropy

mucus