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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

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
What is meant by the term ‘non aqueous’ solution
Solvent in the solution is not water
26
What are the types of water
Potable- drawn from water supply Purifies- boiled /cooled before use Water for injections- sterilised/pyrogen free= parenteral solutions
27
What are the 5 types of pharmalogical solutions
Solid in liquid Liquid in liquid Solid in solid Gas in liquid Gas in gas
28
Define a solid in liquid solution
Homogenous one phase solid dispersed on molecular level in suitable solvent
29
Explain a liquid in liquid solution
One phase molecular dispersion of 2 liquids which are miscible
30
What is the difference between solubility and miscibility
Soluble- solid in liquid Miscible liquid in liquid
31
Explain a solid in solid solution
Molecular dispersion of a solid solute in solid solvent
32
When are solid in solid solutions used
Enhance the dissolution of poorly soluble drugs
33
What is a gas solution
Compressed air in cylinders
34
Give an example of gas in liquid solution
Dissolved gas found in liquids eg oxygen in blood
35
What do we call a solution/suspension in liquefies propellant
Pmdi
36
What are the 7 factors affecting solubility
Particle size Temperature Pressure Molecular size Nature of solute/solvent Polarity Polymorphs
37
Why do drugs need to be solubility enhanced
Many drugs fail to reach the market due to low bioavailability therefore given at high dose
38
List the ways in which solubili Tttt can be enhanced
Cosolvency Ph adjustment Solubilisation Chemical modification Salt formation Particle size control Temp
39
Explain what a cosolvent is
Miscible with main solvent & can dissolve with material
40
Give an example of a surfactant
Cyclodextrin Non toxic/miscible/ good odour and taste
41
How does particle size affect solubilty
Lipinski rule Snakler size = increase in drug solubility
42
Define surface tension
Tendency of surface of liquids to resist external forces such as gravity
43
What can cause surface tension
Intermolecular attraction between h2O molecules
44
Define cohesiveness
Bulk liquid surrounded by molecules with equal attraction
45
In terms of force/unit, describe surface tension
Force/unit length required to be applied parallel to counteract
46
What is the unit for surface tension
Dynes/cm
47
Describe an interface
Boundary between 2+ phases which exist together
48
List the important interfacial phenomena in pharmacy
Absorption of drugs Penetration of molecules through bio system Emulsion formation and stability Dispersion of insoluble particles in liquid media to form
49
Example of gas liquid interaction
Water exposed to atmosphere
50
Example of gas solid phase
Powders exposed to atmosphere
51
Example of liquid liquid phase
Emulsion
52
Example of solid liquid phase
Suspension
53
Example of solid solid phase
Powder particles in contact with each other
54
How does symmetry differ between the interactions of layers
Top asymmetry Middle more symmetry Bottom even more symmetrical
55
Explain what is meant by surfactant
Amphipathic Both hydrophilic and hydrophobic
56
Explain what is meant by ampipathic orientation
Like with like and opposite avoid each other
57
What is the link between surface concentration and surface tension
As conce + surface tension - until cannot decrease any further
58
Where do hydrophobic groups aggregate
Form core of micelle to get rid of hydrophobic moieties
59
What is the critical micelle concentrat
Point at which micelle start to form
60
What do the formation of bilayers in micelle form
Vesicles
61
Use of vesicles
Encapsulate drugs for targeting or sustained purpose release
62
Difference between absorption snd adsorption
Sorption- movement of material from one phase to another Ad- penetration of material Ad - accumulation of substances
63
What are the two types of ADsorption
Chemical - chemisorption- bound by stronger than van der waal forces - irreversible Physical- physisorption - weaker than vdw forces - reversible
64
What is a pharmaceutical application of adsorption
Taste making
65
List routes of admin of liquid dosages
Oral Ocular Optic Rectal Parenteral Topical
66
Give examples of pharmaceutical emulsions
Lotions/ creams/ ointment
67
What happens when 2 immiscible liquids mix
High surface tension & thermodynamically unstabke
68
Why do we add emulsifyer to imiiscible liquids
Lower interfacial tension and make them more stable
69
Define emulsions
2 immiscible liquids one if which finely subdivided and uniformly distributed as droplets
70
In solutions, What phase is dispersed phase
Internal
71
What phase is continuous phase
External
72
List properties if emulsifying agent
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
Why are antioxidants added to emulsions
Prevent autoxidation of oil
74
Define bancroft rule
Phase oil/water in which emulsifier is more soluble is the external phase
75
In size order list the droplet size of emulsions
Coarse Fine Micro emulsion
76
What effect does size of droplet have on stability
Bigger droplet = more unstable
77
If a higher hlb value is shown, what does that mean
Highly polar and higher solubility in water
78
If a low hlb value is shown what does that show
More lipophilic - less soluble in water
79
List types of emulsion test
Dilution test Conductivity test Dye sol test Fluoroscence test
80
How is the dilution test done
Dilute with oil /water
81
How is a conductivity test done
Attach to circuit Water good Oil bad
82
How is a dye solubility test done
Use a dye with known phase and like will dissolve in like
83
How would you conduct a fluoroscent test
W/o give light O/ w will not
84
Where do sedimentation and creaming occur
sediment bottom Cream top
85
Describe the process of flocculations
Aggregation of droplets which can lead to coalescence
86
Define creaming
Rising or downward creaming of globules or floccules to form a concentrated layer
87
What will happen in creaming phase
Droplets remain independent Redispersible
88
Why is creaming undesirable
Inelegant in appearance and could give incorrect dose Increase chance of coalescence
89
How would you avoid creaming
Stokes law- referring to velocity of creaming
90
Ways to avoid creaming
Decrease droplet size Increase viscosity Decrease density between the phases
91
Describe coalescence and breaking
2+ droplets merge to form bugger droplet Irreversible
92
How do you prevent coalescence
Strong stable interfacial
93
Causes of coalescence and breaking
Loss of emulsifyer addition of incompatible chemical Bacteria growth Temp changes

PJ1310 Science Of Medicines Yr1 (15 decks)

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