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Flashcards in Methods of formulation Deck (74):
1

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

True

2

What is a sol?

A colloid suspension of solid particles in a liquid

3

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

False - two liquids

4

How is a foam formed?

When many gas particles are trapped in a liquid or solid

5

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

True

6

What is meant by a lyophobic colloid?

Solvent hating

7

What is meant by a lyophilic colloid?

Solvent loving

8

Lyophilic sols exhibit low viscosity. True or false?

False - high viscosity

9

Are the particles in a lyophilic sol symmetrical or assymetrical?

Assymetrical

10

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

True

11

Lyophobic sols exhibit high viscosity. True or false?

False - low viscosity

12

Lyophobic sols contain symmetrical particles. True or false?

True

13

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

True

14

How are lyophobic dispersion systems formed?

The dispersion of oil in water

15

What is meant by dispersion?

The breakdown of coarse material by colloid mills or ultrasonic treatment

16

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?

False - the fast production

17

What are random zig zag collisions a result of?

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

18

At what size will particles sediment under gravity?

0.5 micrometres or more

19

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

True

20

Aggregates with an open structure are called ______

flocs

21

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

True

22

What is a gel containing no liquid called?

A xerogel

23

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

Composed of charged particles and form gels by flocculation

24

Which type of bonds hold type 1 gels together?

Covalent

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