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Flashcards in methods of formulation 2 Deck (41):
1

How are insoluble particles dealt with in the lungs?

They are trapped by mucus and swept upwards by the beating cilia to the throat and swallowed

2

Give 3 drugs given by the lungs for systemic delivery:

- sodium cromoglicate (hay fever)
- isoprenaline (bradycardia)
- ergotamine (migraines)

3

What is the optimal particle size for aerosols?

1-5um
>10 = deposited in throat and mouth
<0.5 = exhaled

4

aerosols are lyophobic colloids, so how are they prepared?

by dispersion or condensation

5

How are aerosols administered?

by inhalers or nebulisers

6

What is the difference between an MDI and a DPI?

MDI = generate an aerosol when deployed
DPI = contain capsules/blisters loaded with drug particles

7

What are nebulisers used for?

treatment of COPD, CF, asthma, antibiotics, opioids

8

What is local nasal drug delivery used to treat?

nasal congestion, infection, hayfever

9

What is systemic nasal drug delivery used to treat?

analgesics, erectile dysfunction, vaccines, sympathomimetics (adrenaline, dopamine)

10

What particle size is good for nasal drug delivery?

5-10um

11

Where is the main site of drug absorption for nasal delivery?

epithelium of the nasal turbinates

12

How do lipophilic drugs cross the epithelium of the nose?

by paracellular diffusion (between cells as oppose to transcellular which is through cells)

13

What indication does PenFent have that is good?

used to relive breakthrough pain in people already receving opioids on a regular basis

14

What are the advantages of rectal drug delivery?

- avoids oral route
- taste isn't an issue
- small and large doses can be given
- no protease activity in the rectum
- skilled HCP not needed

15

What are the disadvantages of rectal drug delivery?

- patient acceptance
- slow and sometimes incomplete drug absorption
- development of proctitis (inflammation) with prolonged use
- problems with leakage and insertion
- short shelf life
- small market size (<1%)

16

What do the nose, lungs and rectum all have in common?

all have goblet cells which release mucus

17

What is the pH of the rectum?

around 7.5 (more alkaline in children)

18

Why can't acidic/alkali drugs not be given via rectum?

As the rectum doesn't have buffering capacity

19

How does rectal delivery avoid first pass metabolism?

By passing straight to the vena cava

20

Why is rate and extent of absorption of rectal delivery lower than the oral route?

- limited SA for absorption
- reduced fluid volume, affecting drug dissolution

21

What is the advantage and disadvantage of using surfactants in rectal drugs?

good because can improve drug delivery and prevent aggregation,
but bad because can cause rectal irritation

22

depending on the vehicle, a suppository will either...

melt on the mucous layer or dissolve in the rectal fluid

23

How much do rectal suppositories weigh?

1-4g

24

What are the 2 types of bases used in suppositories?

1. water soluble bases (used less)
2. glyceride type fatty acids (natural/synthetic oils such as triglycerides, saturated fatty acids, waxes, fatty alcohols )

25

Whichever suppository base is used, they should all...?

- have a mtp small enough to be solid after preparation
- melt/dissolve at room temp
- dissolve in the available rectal fluid
- chemically and physically stable during storage
- be non-irritant
- have an appropriate viscosity to minimise leakage

26

What is the mpt like of PEG bases? And what is a packaging consideration?

high mpt so good for tropical climates but they can oxidise forming peroxides on storage so airtight packaging is needed

27

Do you want suppositories to be water soluble in a fatty base?

yes - prevents sedimentation, smaller particles means faster dissolution rate

28

In what 3 ways are suppositories formed?

- hand rolling (small scale)
- compression moulding (semi automated)
- fusion moulding (semi-automated)

29

What will viscosity enhancers do in suppositories and what are some examples?

slows down drug release (as particles are trapped)
- colloidal silicon oxide, aluminium monostearate

30

the ideal suppository should weigh... and contain drug particles of ...

3.5g and contain drug particles of 25um

31

What kind of conditions are lipid based suppositories used to treat?

haemorrhoids

32

Why are rectal tablets not used often?

Due to the low amount of water present in the rectum, limiting dissolution of tablets

33

Rectal tablets which release CO2 can be useful, why?

the gas released, stimulates defecation

34

Why are enemas good?

solutions/emulsions/suspensions
- have a large volume enabling drug to reach upper part of rectum and sigmoid colon

35

What are the local uses of vaginal drug delivery?

anti-fungal - clotrimazole
spermicides
microbicides - to prevent HIV transmission, chlamydia

36

What are the systemic uses of vaginal drug delivery?

HRT mainly e.g. oestrogens
(higher bioavailability than oral HRT)

37

What is the pH of a healthy vagina? why is this?

3.5-4.5
- due to conversion of glycogen to lactic acid by lactobacillus

38

Vaginal drug delivery is affected by...?

menopause
pregnancy
phase of menstrual cycle
candida infection
- NOT HPV infection

39

What type of bases should pessaries be made from?

glycerol-gelatin bases (water soluble to ensure rapid release and miscibility)

40

What are 'rings' used for?

contraceptives

41

What is a filler used in vaginal tablets and why?

lactose as this is a natural substrate for the vaginal microflora