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The Medicine (Y2) > Methods of formulation > Flashcards

Methods of formulation Flashcards

1
Q

To be classified as a colloid, the particles must not settle under gravity. True or false?

A

True

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2
Q

What is a sol?

A

A colloid suspension of solid particles in a liquid

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3
Q

An emulsion is a mixture of two solids. True or false?

A

False - two liquids

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4
Q

How is a foam formed?

A

When many gas particles are trapped in a liquid or solid

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5
Q

An aerosol contains small particles of liquid or solid dispersed in a gas, True or false?

A

True

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6
Q

What is meant by a lyophobic colloid?

A

Solvent hating

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7
Q

What is meant by a lyophilic colloid?

A

Solvent loving

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8
Q

Lyophilic sols exhibit low viscosity. True or false?

A

False - high viscosity

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9
Q

Are the particles in a lyophilic sol symmetrical or assymetrical?

A

Assymetrical

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10
Q

Lyophilic particles are stable to addition of electrolytes. True or false?

A

True

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11
Q

Lyophobic sols exhibit high viscosity. True or false?

A

False - low viscosity

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12
Q

Lyophobic sols contain symmetrical particles. True or false?

A

True

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13
Q

Lyophobic sols are sensitive to the addition of electrolytes. True or false?

A

True

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14
Q

How are lyophobic dispersion systems formed?

A

The dispersion of oil in water

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15
Q

What is meant by dispersion?

A

The breakdown of coarse material by colloid mills or ultrasonic treatment

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16
Q

Condensation involves the slow production of a supersaturated solution of the colloidal material under conditions that cause formation of colloidal particles and not a precipitate. True or false?

A

False - the fast production

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17
Q

What are random zig zag collisions a result of?

A

Brownian motion - colloidal particles are able to spontaneously move from high conc to low conc

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18
Q

At what size will particles sediment under gravity?

A

0.5 micrometres or more

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19
Q

Particles less than 0.5 micrometres have to be sedimented by centrifugation. True or false?

A

True

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20
Q

Aggregates with an open structure are called ______

A

flocs

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21
Q

The majority of gels are formed by aggregation of colloidal sol particles. True or false?

A

True

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22
Q

What is a gel containing no liquid called?

A

A xerogel

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23
Q

Bentonite is a clay. What are clays composed of and how do they turn into gels?

A

Composed of charged particles and form gels by flocculation

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24
Q

Which type of bonds hold type 1 gels together?

A

Covalent

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25
Which type of bonds hold type 2 gels together?
Weak bonds e.g. hydrogen bonds
26
Type 1 gels are heat reversible. True or false?
False - they are irreversible
27
Type 1 gels swell in water and dissolve. True or false?
False - do not dissolve due to stabilising links
28
Type 2 gels are heat reversible. What is meant by this?
On heating or cooling there is a transition from sol to gel and vise versa
29
As temperature is increased, the solubility of type 2 gels increases. True or false?
False - decreases
30
Why does the solubility of type 2 gels decrease as temperature is increased?
Because type 2 gels form micelles and upon warming, more and more micelles form. The micelles are formed so closely together that movement is prevented and a gel phase is formed
31
A surfactant is an amphipathic molecule. What is meant by this?
It contains both hydrophilic groups and hydrophobic
32
CMC decreases as length of hydrocarbon chain increases. True or false?
True
33
How can the stability of an emulsion be increased?
Reduce globlet size Decrease density difference Increase viscosity of continuous phase
34
What particle size is needed for good penetration into the airways?
1-5 micrometres
35
Aerosol particles above 20 micrometres are deposited in the mouth and throat. True or false?
False - more than 10 micrometres
36
What happens if the aerosol particles are less than 0.5 micrometres?
They may be exhaled
37
What is a foam?
A dispersion of a gas in a liquid
38
Surfactants are required for the formation of foams and emulsions. True or false?
True
39
What are the two ways in which an aerosol can be prepared?
Dispersion | Condensation
40
What is the fate of aerosol particles that are 1-5nm in diameter?
They are exhaled
41
Drugs for treatment of erectile dysfunction can be taken through nasal delivery formulations. True or false?
True
42
How long is the nasal cavity?
12-14cm long
43
In the nasal cavity, cilia of the nasal vestibule filter out particles of which diameter?
over 10 micrometres
44
What is the main drug absorption site in the nasal cavity?
The epithelium of the nasal turbinates
45
Particles of which diameter are deposited in the nasal cavity?
5-10 micrometres
46
What is PecFent and what is it used for?
A nasal spray with the API fentanyl - used for breakthrough pain in people already receiving opioids on a regular basis
47
All drugs which are orally administered can be given rectally. True or false?
True - but may not be as effective
48
What are some disadvantages of rectal delivery systems?
``` Not favoured by patients Development of proctitis Slow and sometimes incomplete absorption of drug Problems with insertion Short shelf-life ```
49
Are there villi present on the rectum?
No - it has a flat surface with no villi
50
The rectum wall is composed of multiple layers of epithelium. True or false?
False - single layer of epithelium, composed of cylindrical cells and goblet cells that secrete mucous
51
What is the pH of the rectum in adults?
pH 7.5 and is slightly more alkaline in children
52
How many veins serve the rectum and what are they called?
Inferior, middle and superior haemorrhoidal veins
53
Where do the inferior and middle haemorrhoidal veins drain?
Into the inferior vena cava
54
Where does the superior haemorrhoidal vein drain?
hepatic portal vein
55
How does drug absorption take place in the rectum?
By passive diffusion
56
Why is bioavailability in the rectum unpredictable?
Because of inter-individual variations and due to venous drainage
57
Why is rate and extent of drug absorption via the rectum not as good as oral?
Limited SA | low fluid volume - effects dissolution of drug
58
There is a lot of fluid present in the rectum. True or false?
False - approx 3mls of mucous only
59
Water-soluble bases (suppositories) are mostly used for laxative purposes. True or false?
False - glycerinated gelatin bases are used (water soluble bases are used much less frequently)
60
Which type of suppository bases have a melting point above body temp?
PEG
61
To prevent sedimentation during manufacture what should the drug particle size of suppositories be?
less than 150 micrometres
62
Drug particles (suppositories) less than ___ micrometres will not cause irritation to the patient
50 micrometres
63
What are the 3 ways in which suppositories are formed?
Hand-rolling Compression Fusion moulding
64
Inclusion of viscosity enhancers in suppositories slows down drug release. True or false?
True
65
What is the ideal weight of a suppository?
1-4g
66
What are rectal capsules used for?
Systemic drug delivery - usually filled with a solution or suspension of drug
67
Why aren't rectal tablets not an ideal dosage form?
Due to the lack of water in the rectum - limiting dissolution
68
Rectal tablets that release CO2 after insertion stimulate what?
Defecation - discharge of faeces from the body
69
Progesterone administered orally has a higher bioavailability than that administered vaginally. True or false?
False
70
How long is the vagina?
4-6 inches
71
What is the pH of the vagina in a healthy adult woman?
3.5-4.5
72
Why is the vagina weakly acidic?
Due to the conversion of glycogen to lactic acid by lactobacillus
73
What base should be used to make pessaries?
Glycerol-gelatin base
74
What filler is usually used in vaginal tablets?
Lactose as it is a natural substrate for the vaginal microflora

The Medicine (Y2) (34 decks)

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