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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
Q

Which type of bonds hold type 2 gels together?

A

Weak bonds e.g. hydrogen bonds

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26
Q

Type 1 gels are heat reversible. True or false?

A

False - they are irreversible

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27
Q

Type 1 gels swell in water and dissolve. True or false?

A

False - do not dissolve due to stabilising links

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28
Q

Type 2 gels are heat reversible. What is meant by this?

A

On heating or cooling there is a transition from sol to gel and vise versa

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29
Q

As temperature is increased, the solubility of type 2 gels increases. True or false?

A

False - decreases

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30
Q

Why does the solubility of type 2 gels decrease as temperature is increased?

A

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
Q

A surfactant is an amphipathic molecule. What is meant by this?

A

It contains both hydrophilic groups and hydrophobic

32
Q

CMC decreases as length of hydrocarbon chain increases. True or false?

33
Q

How can the stability of an emulsion be increased?

A

Reduce globlet size
Decrease density difference
Increase viscosity of continuous phase

34
Q

What particle size is needed for good penetration into the airways?

A

1-5 micrometres

35
Q

Aerosol particles above 20 micrometres are deposited in the mouth and throat. True or false?

A

False - more than 10 micrometres

36
Q

What happens if the aerosol particles are less than 0.5 micrometres?

A

They may be exhaled

37
Q

What is a foam?

A

A dispersion of a gas in a liquid

38
Q

Surfactants are required for the formation of foams and emulsions. True or false?

39
Q

What are the two ways in which an aerosol can be prepared?

A

Dispersion

Condensation

40
Q

What is the fate of aerosol particles that are 1-5nm in diameter?

A

They are exhaled

41
Q

Drugs for treatment of erectile dysfunction can be taken through nasal delivery formulations. True or false?

42
Q

How long is the nasal cavity?

A

12-14cm long

43
Q

In the nasal cavity, cilia of the nasal vestibule filter out particles of which diameter?

A

over 10 micrometres

44
Q

What is the main drug absorption site in the nasal cavity?

A

The epithelium of the nasal turbinates

45
Q

Particles of which diameter are deposited in the nasal cavity?

A

5-10 micrometres

46
Q

What is PecFent and what is it used for?

A

A nasal spray with the API fentanyl - used for breakthrough pain in people already receiving opioids on a regular basis

47
Q

All drugs which are orally administered can be given rectally. True or false?

A

True - but may not be as effective

48
Q

What are some disadvantages of rectal delivery systems?

A 
Not favoured by patients
Development of proctitis 
Slow and sometimes incomplete absorption of drug 
Problems with insertion 
Short shelf-life
49
Q

Are there villi present on the rectum?

A

No - it has a flat surface with no villi

50
Q

The rectum wall is composed of multiple layers of epithelium. True or false?

A

False - single layer of epithelium, composed of cylindrical cells and goblet cells that secrete mucous

51
Q

What is the pH of the rectum in adults?

A

pH 7.5 and is slightly more alkaline in children

52
Q

How many veins serve the rectum and what are they called?

A

Inferior, middle and superior haemorrhoidal veins

53
Q

Where do the inferior and middle haemorrhoidal veins drain?

A

Into the inferior vena cava

54
Q

Where does the superior haemorrhoidal vein drain?

A

hepatic portal vein

55
Q

How does drug absorption take place in the rectum?

A

By passive diffusion

56
Q

Why is bioavailability in the rectum unpredictable?

A

Because of inter-individual variations and due to venous drainage

57
Q

Why is rate and extent of drug absorption via the rectum not as good as oral?

A

Limited SA

low fluid volume - effects dissolution of drug

58
Q

There is a lot of fluid present in the rectum. True or false?

A

False - approx 3mls of mucous only

59
Q

Water-soluble bases (suppositories) are mostly used for laxative purposes. True or false?

A

False - glycerinated gelatin bases are used (water soluble bases are used much less frequently)

60
Q

Which type of suppository bases have a melting point above body temp?

61
Q

To prevent sedimentation during manufacture what should the drug particle size of suppositories be?

A

less than 150 micrometres

62
Q

Drug particles (suppositories) less than ___ micrometres will not cause irritation to the patient

A

50 micrometres

63
Q

What are the 3 ways in which suppositories are formed?

A

Hand-rolling
Compression
Fusion moulding

64
Q

Inclusion of viscosity enhancers in suppositories slows down drug release. True or false?

65
Q

What is the ideal weight of a suppository?

66
Q

What are rectal capsules used for?

A

Systemic drug delivery - usually filled with a solution or suspension of drug

67
Q

Why aren’t rectal tablets not an ideal dosage form?

A

Due to the lack of water in the rectum - limiting dissolution

68
Q

Rectal tablets that release CO2 after insertion stimulate what?

A

Defecation - discharge of faeces from the body

69
Q

Progesterone administered orally has a higher bioavailability than that administered vaginally. True or false?

70
Q

How long is the vagina?

A

4-6 inches

71
Q

What is the pH of the vagina in a healthy adult woman?

72
Q

Why is the vagina weakly acidic?

A

Due to the conversion of glycogen to lactic acid by lactobacillus

73
Q

What base should be used to make pessaries?

A

Glycerol-gelatin base

74
Q

What filler is usually used in vaginal tablets?

A

Lactose as it is a natural substrate for the vaginal microflora

The Medicine (Y2) (34 decks)

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