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PJ1310 Science Of Medicines Yr1 > Test 6 Solutions/Solubility/emulsions/interfacial Properties > Flashcards

Test 6 Solutions/Solubility/emulsions/interfacial Properties Flashcards

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1
Q

Define the term solution

A

Homogenous mixture of 2+ substances

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2
Q

Define term solute

A

Substance present in smaller amount

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3
Q

Define the term solvent

A

Substance present in larger amounts

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4
Q

Define the term solubility

A

No of parts of solvent which will dissolve in 1 part
(W/V)

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5
Q

What is an unsaturated solution

A

Solution where more solute can dissolve

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6
Q

What is a saturated solution

A

Solution where no more solute dissolves

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7
Q

Explain the meaning of a supersaturated solution

A

More solute in a solution which has formed unstable crystal forms

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8
Q

Explain the term aqueous solubility of drug

A

Concentration at which solution is saturated. Any further solute will form a precipitation

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9
Q

Define the term immiscibility

A

2 LIQUIDS do not mix

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10
Q

Define the term miscibility

A

Two liquids CAN mix

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11
Q

Why is the maximum level of solubility important

A

Maximum level of solubility dictates rate of dissolution

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12
Q

What is good practice in terms of solubility

A

Good practice is to keep solutions below solubility

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13
Q

Explain a way to produce an easy to manage formulation

A

Make solution very soluble

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14
Q

What does low aqueous solubility propose?

A

Problems with formulation & bioavailability

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15
Q

Recall the pathway of drug from shelf to small intestine

A

Disintegration
Dissolution
Deagregation
Dissolution
Drug in solution
Absorption

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16
Q

Name a substance which is very soluble in water

A

Glucose

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17
Q

Why is cyclohexane insoluble in water

A

Dispersion forces

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18
Q

Recall the general rule for dissolution

A

Like dissolves with like

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19
Q

What is the difference between dissolution and reaction

A

Dissolution is a physical change however if the original has changed that is a reaction

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20
Q

Describe solutions

A

Well mixed single phase
Homogenous
Transparent
Not separated by filter
Cannot separate by standing

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21
Q

What are the pros of a solution

A

Easier to swallow
Suitable for children & geriatrics
Faster therapeutic response
Uniform distribution if drug throughout preparation
Reduced irritation to gut mucosa

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22
Q

What are the cons of solutions

A

Bulky/inconvenient transport
If container breaks all is lost
Poor stability
Microbial contamination is likely
Inaccurate dosing
Difficult to mask bitter taste

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23
Q

What are the pros of aqueous solution

A

Lack of toxicity
Non expensive
Physiological compatibility

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24
Q

What are the cons of aqueous solution

A

Hydrolysis of some drugs

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25
Q

What is meant by the term ‘non aqueous’ solution

A

Solvent in the solution is not water

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26
Q

What are the types of water

A

Potable- drawn from water supply
Purifies- boiled /cooled before use
Water for injections- sterilised/pyrogen free= parenteral solutions

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27
Q

What are the 5 types of pharmalogical solutions

A

Solid in liquid
Liquid in liquid
Solid in solid
Gas in liquid
Gas in gas

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28
Q

Define a solid in liquid solution

A

Homogenous one phase solid dispersed on molecular level in suitable solvent

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29
Q

Explain a liquid in liquid solution

A

One phase molecular dispersion of 2 liquids which are miscible

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30
Q

What is the difference between solubility and miscibility

A

Soluble- solid in liquid
Miscible liquid in liquid

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31
Q

Explain a solid in solid solution

A

Molecular dispersion of a solid solute in solid solvent

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32
Q

When are solid in solid solutions used

A

Enhance the dissolution of poorly soluble drugs

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33
Q

What is a gas solution

A

Compressed air in cylinders

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34
Q

Give an example of gas in liquid solution

A

Dissolved gas found in liquids eg oxygen in blood

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35
Q

What do we call a solution/suspension in liquefies propellant

A

Pmdi

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36
Q

What are the 7 factors affecting solubility

A

Particle size
Temperature
Pressure
Molecular size
Nature of solute/solvent
Polarity
Polymorphs

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37
Q

Why do drugs need to be solubility enhanced

A

Many drugs fail to reach the market due to low bioavailability therefore given at high dose

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38
Q

List the ways in which solubili Tttt can be enhanced

A

Cosolvency
Ph adjustment
Solubilisation
Chemical modification
Salt formation
Particle size control
Temp

39
Q

Explain what a cosolvent is

A

Miscible with main solvent & can dissolve with material

40
Q

Give an example of a surfactant

A

Cyclodextrin

Non toxic/miscible/ good odour and taste

41
Q

How does particle size affect solubilty

A

Lipinski rule
Snakler size = increase in drug solubility

42
Q

Define surface tension

A

Tendency of surface of liquids to resist external forces such as gravity

43
Q

What can cause surface tension

A

Intermolecular attraction between h2O molecules

44
Q

Define cohesiveness

A

Bulk liquid surrounded by molecules with equal attraction

45
Q

In terms of force/unit, describe surface tension

A

Force/unit length required to be applied parallel to counteract

46
Q

What is the unit for surface tension

A

Dynes/cm

47
Q

Describe an interface

A

Boundary between 2+ phases which exist together

48
Q

List the important interfacial phenomena in pharmacy

A

Absorption of drugs
Penetration of molecules through bio system
Emulsion formation and stability
Dispersion of insoluble particles in liquid media to form

49
Q

Example of gas liquid interaction

A

Water exposed to atmosphere

50
Q

Example of gas solid phase

A

Powders exposed to atmosphere

51
Q

Example of liquid liquid phase

A

Emulsion

52
Q

Example of solid liquid phase

A

Suspension

53
Q

Example of solid solid phase

A

Powder particles in contact with each other

54
Q

How does symmetry differ between the interactions of layers

A

Top asymmetry
Middle more symmetry
Bottom even more symmetrical

55
Q

Explain what is meant by surfactant

A

Amphipathic
Both hydrophilic and hydrophobic

56
Q

Explain what is meant by ampipathic orientation

A

Like with like and opposite avoid each other

57
Q

What is the link between surface concentration and surface tension

A

As conce + surface tension - until cannot decrease any further

58
Q

Where do hydrophobic groups aggregate

A

Form core of micelle to get rid of hydrophobic moieties

59
Q

What is the critical micelle concentrat

A

Point at which micelle start to form

60
Q

What do the formation of bilayers in micelle form

A

Vesicles

61
Q

Use of vesicles

A

Encapsulate drugs for targeting or sustained purpose release

62
Q

Difference between absorption snd adsorption

A

Sorption- movement of material from one phase to another
Ad- penetration of material
Ad - accumulation of substances

63
Q

What are the two types of ADsorption

A

Chemical - chemisorption- bound by stronger than van der waal forces - irreversible

Physical- physisorption - weaker than vdw forces - reversible

64
Q

What is a pharmaceutical application of adsorption

A

Taste making

65
Q

List routes of admin of liquid dosages

A

Oral
Ocular
Optic
Rectal
Parenteral
Topical

66
Q

Give examples of pharmaceutical emulsions

A

Lotions/ creams/ ointment

67
Q

What happens when 2 immiscible liquids mix

A

High surface tension & thermodynamically unstabke

68
Q

Why do we add emulsifyer to imiiscible liquids

A

Lower interfacial tension and make them more stable

69
Q

Define emulsions

A

2 immiscible liquids one if which finely subdivided and uniformly distributed as droplets

70
Q

In solutions, What phase is dispersed phase

A

Internal

71
Q

What phase is continuous phase

A

External

72
Q

List properties if emulsifying agent

A

Decrease surface tension between 2 immiscible liquids
Non toxic
Doesn’t interfere with stability of efficacy of drug
Stable to other microorganisms
No taste/ odour

73
Q

Why are antioxidants added to emulsions

A

Prevent autoxidation of oil

74
Q

Define bancroft rule

A

Phase oil/water in which emulsifier is more soluble is the external phase

75
Q

In size order list the droplet size of emulsions

A

Coarse
Fine
Micro emulsion

76
Q

What effect does size of droplet have on stability

A

Bigger droplet = more unstable

77
Q

If a higher hlb value is shown, what does that mean

A

Highly polar and higher solubility in water

78
Q

If a low hlb value is shown what does that show

A

More lipophilic - less soluble in water

79
Q

List types of emulsion test

A

Dilution test
Conductivity test
Dye sol test
Fluoroscence test

80
Q

How is the dilution test done

A

Dilute with oil /water

81
Q

How is a conductivity test done

A

Attach to circuit
Water good
Oil bad

82
Q

How is a dye solubility test done

A

Use a dye with known phase and like will dissolve in like

83
Q

How would you conduct a fluoroscent test

A

W/o give light
O/ w will not

84
Q

Where do sedimentation and creaming occur

A

sediment bottom
Cream top

85
Q

Describe the process of flocculations

A

Aggregation of droplets which can lead to coalescence

86
Q

Define creaming

A

Rising or downward creaming of globules or floccules to form a concentrated layer

87
Q

What will happen in creaming phase

A

Droplets remain independent
Redispersible

88
Q

Why is creaming undesirable

A

Inelegant in appearance and could give incorrect dose
Increase chance of coalescence

89
Q

How would you avoid creaming

A

Stokes law- referring to velocity of creaming

90
Q

Ways to avoid creaming

A

Decrease droplet size
Increase viscosity
Decrease density between the phases

91
Q

Describe coalescence and breaking

A

2+ droplets merge to form bugger droplet
Irreversible

92
Q

How do you prevent coalescence

A

Strong stable interfacial

93
Q

Causes of coalescence and breaking

A

Loss of emulsifyer
addition of incompatible chemical
Bacteria growth
Temp changes

PJ1310 Science Of Medicines Yr1 (15 decks)

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