Brainscape's Knowledge GenomeTM

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


See full index

PMP 102 > Stability > Flashcards

Stability Flashcards

1
Q

What interaction do lyophobic systems have with the solvent?

A

Poor

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

What physical stability do suspensions have?

A

Coarse

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

Why are large particles sedimenting problematic?

A

Not mixed evenly
Uneven distribution

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

What governs sedimentation, enabling redispertion?

A

Stokes’ Law

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

What does homogeneous dose mean?

A

Mixed dose

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

What does heterogeneous dose mean?

A

Not a well dispersed dose

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

What are the main instability phenomenas of macro particles?

A

Aggregation
Coagulation
Flocculations
Sedimentation
Caking
Ostwald ripening

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

What is aggregation?

A

Particles in groups

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

What is coagulation?

A

Closely aggregated and difficult to redisperse

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

What is flocculation?

A

Aggregates have an open structure with particles a small distance apart, attracted by a weak force to form flocs or flakes

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

What is sedimentation?

A

Process of settling or being deposited as a sediment

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

What is caking?

A

Defloculatted particles form cakes which can be difficult to re-suspend

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

What is Ostwald ripening?

A

Dissolution of small crystals

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

What does physical instability result in?

A

Poor dosing

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

What are the main factors affecting stability?

A

Kinetic properties
Size/shape
Electrical properties

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

What does the brownian motion and diffusion mean?

A

Particles diffuse from a high concentration

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

What law is diffusion rate based on?

A

Fick’s first law

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

What is the diffusion rate equation?

A

dm=-DA dc
dt. dx

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

What does dm over dt mean?

A

Mass of substances

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

What does D mean in Fick’s first law?

A

Diffusion coefficient

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

What does A mean in Fick’s first law?

A

Area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What does dc over dx mean in Fick’s first law?

A

Concentration gradient

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

What does viscosity relate to?

A

Molecular weight of suspended particles/suspending agents

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

How do we prevent sedimentation?

A

Form smaller particles
Decrease the density difference

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

What are the names of each layer in the electrical double layer of ions?

A

Stern layer
Diffuse layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What does zeta potential stand for?

A

Magnitude and type of the electrical potential at the slipping plane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What does low zeta potential mean?

A

Prone to aggregate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What does high zeta potential mean?

A

Tend to remain dispersed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the factors affecting zeta potential?

A

Ion concentration - determines magnitude
pH of continuous phase- alters the ionisation

30
Q

What does the DLVO graph show?

A

Quantitative approach to the stability of lyophobic systems

31
Q

What does the DLVO graph assume?

A

That the only interactions involved are van Der walls (VA) and electrostatic repulsive forces (VR)

32
Q

What is the equation for DLVO?

A

VT=VA+VR

33
Q

What is the instability phenomena?

A

Not redispersable

34
Q

What is emulsion stability?

A

Droplets can retain their initial character and remain uniformly distributed throughout the continuous phase.

35
Q

When can emulsion stability occur?

A

Phase inversion
Creaming
Flocculation
Coalescence
Ostwald ripening

36
Q

What is phase inversion?

A

Oil in water emulsion stabilised by ionic surfactant/ co-surfactant

37
Q

What is creaming?

A

Different density between oil and water, the oil droplets tend to concentrate at the top of the emulsion.

38
Q

What is flocculation?

A

When two or more emulsion droplets aggregate without losing their individual identity

39
Q

What is coalescence?

A

When two or more droplets collide me form one larger droplet and is irreversible

40
Q

What is Ostwald ripening?

A

Collision between two droplets may cause one bigger droplet and one smaller droplet

41
Q

What does the van der waals forces in the DLVO graph explain?

A

Explains why some colloidal particles aggregate
Eva use energy attraction varies with the distance between the pairs of atoms or molecules or neighbouring particles with the inverse of the 6th power.
A=1
H*6

42
Q

What does the electrostatic repulsive forces explain in the DLVO graph?

A

Explains why some colloidal particles stay separated
Arrives from the interaction of the electronic double layers surrounding pairs of particles
Depends on zeta potential

43
Q

What does low zeta potential mean?

A

Flocculated

44
Q

What does high zeta potential mean?

A

Stable

45
Q

What are the factors in the secondary minimum on the DLVO graph?

A

Forces of attraction are weak
Flocculation
Minimum attraction at large distances of separation

46
Q

What are the factors of the primary maximum on the DLVO graph?

A

Particles come closer so there are some repulsion
Height of this repulsion determines the stability of the system (vmax)

47
Q

What are the factors of the primary minimum in the DLVO graph?

A

At close approach van der waals forces always dominate over repulsive electrostatic forces
Coagulation that’s irreversible

48
Q

What are the two ways non-ionic surfactants interact with each other?

A

Entropic (steric) effects
Osmotic (salvation) forces

49
Q

What happens when entropic effects happens?

A

The polymer chains on non-ionic surfactants start to overlap
Which leads to a loss of freedom of motion
This situation is thermodynamically unfavourable and forces the droplets apart again

50
Q

What happens when there are osmotic forces in non-ionic surfactants?

A

When two particles come in close contact the polymer chain starts to overlap effectively, leading to concentrated polymer solution
Induces osmotic gradient
Water enters the concentrated region and forces the polymer chains apart.

51
Q

What are the 4 main types of forces?

A

Van der waals (attractive)
Electrostatic (repulsive)
Steric forces (repulsive)
Salvation forces (repulsive)

52
Q

What types of forces do charged colloids use?

A

Van der waals
Electrostatic

53
Q

What types of forces do uncharged colloids use?

A

Van der waals
Steric
Solvation

54
Q

What does stability stand for in medicines?

A

Capacity of a product to remain within specifications to ensure potency, quality or purity

55
Q

What are the 3 types of degradation of medicines?

A

Chemical degradation
Physical degradation
Microbial degradation

56
Q

What is chemical degradation?

A

Decomposition of chemical moiety

57
Q

What is physical degradation?

A

Formulation specific
E.g. caking is suspensions, phase separations, hardness and brittleness in tablets

58
Q

What is microbial degradation?

A

Microbial contamination

59
Q

What can drug instability cause?

A

Inconsistent dosing
Undesired change in performance
Changes in physical appearance
Product failures

60
Q

What are the 4 chemical degradation reactions?

A

Hydrolysis
Oxidation
Photochemical degradation
Polymerisation

61
Q

How do we reduce hydrolysis reaction for chemical degradation?

A

Dry formulations
Adjusting pH to maximum stability
Storage temperature
Coating
Choice of packaging

62
Q

How can we reduce oxidation reaction in chemical degradation?

A

Remove initiators
Exclude O2
Add free radical scavengers

63
Q

How do we reduce photochemical degradation in chemical degradation?

A

Hide from light
Black out containers/ packaging

64
Q

How can we reduce polymerisation reaction in chemical degradation?

A

Hide from UV

65
Q

What are the different reactions in chemical degradation classified?

A

Zero order+ pseudo zero order
First order+ pseudo first order
Second order reactions

66
Q

What is a zero order reaction?

A

The rate of degradation of A is independent of the concentration of the reactants
[A]t= [A]o -kt

67
Q

What are first order reactions?

A

The rate of degradation of A is directly proportional to its contraction [A]

In[A]t=In [A]o-kt

68
Q

What are pseudo zero order reactions?

A

Observed rate constant is an expression for a zero order reaction.

69
Q

What are second order reactions?

A

The rate of degradation of A is directly proportional to its concentration and the concentration of the reactant B
1. =. 1. +kt
[A]t. [A]o

70
Q

What are pseudo first order reactions?

A

Observed rate constant is an expression for a first order reaction

71
Q

How much degradation is allowed?

A

5-10% loss over 5 years

PMP 102 (29 decks)

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