methods of formulation 2

Question 1

How are insoluble particles dealt with in the lungs?

Answer 1

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

Question 2

Give 3 drugs given by the lungs for systemic delivery:

Answer 2

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

Question 3

What is the optimal particle size for aerosols?

Answer 3

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

Question 4

aerosols are lyophobic colloids, so how are they prepared?

Answer 4

by dispersion or condensation

Question 5

How are aerosols administered?

Answer 5

by inhalers or nebulisers

Question 6

What is the difference between an MDI and a DPI?

Answer 6

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

Question 7

What are nebulisers used for?

Answer 7

treatment of COPD, CF, asthma, antibiotics, opioids

Question 8

What is local nasal drug delivery used to treat?

Answer 8

nasal congestion, infection, hayfever

Question 9

What is systemic nasal drug delivery used to treat?

Answer 9

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

Question 10

What particle size is good for nasal drug delivery?

Answer 10

5-10um

Question 11

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

Answer 11

epithelium of the nasal turbinates

Question 12

How do lipophilic drugs cross the epithelium of the nose?

Answer 12

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

Question 13

What indication does PenFent have that is good?

Answer 13

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

Question 14

What are the advantages of rectal drug delivery?

Answer 14

• 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

Question 15

What are the disadvantages of rectal drug delivery?

Answer 15

• 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%)

Question 16

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

Answer 16

all have goblet cells which release mucus

Question 17

What is the pH of the rectum?

Answer 17

around 7.5 (more alkaline in children)

Question 18

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

Answer 18

As the rectum doesn’t have buffering capacity

Question 19

How does rectal delivery avoid first pass metabolism?

Answer 19

By passing straight to the vena cava

Question 20

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

Answer 20

• limited SA for absorption

- reduced fluid volume, affecting drug dissolution

Question 21

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

Answer 21

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

Question 22

depending on the vehicle, a suppository will either…

Answer 22

melt on the mucous layer or dissolve in the rectal fluid

Question 23

How much do rectal suppositories weigh?

Answer 23

1-4g

Question 24

What are the 2 types of bases used in suppositories?

Answer 24

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

Question 25

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

Answer 25

- 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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

yes - prevents sedimentation, smaller particles means faster dissolution rate

Question 28

In what 3 ways are suppositories formed?

Answer 28

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

Question 29

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

Answer 29

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

Question 30

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

Answer 30

3.5g and contain drug particles of 25um

Question 31

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

Answer 31

haemorrhoids

Question 32

Why are rectal tablets not used often?

Answer 32

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

Question 33

Rectal tablets which release CO2 can be useful, why?

Answer 33

the gas released, stimulates defecation

Question 34

Why are enemas good?

Answer 34

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

Question 35

What are the local uses of vaginal drug delivery?

Answer 35

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

Question 36

What are the systemic uses of vaginal drug delivery?

Answer 36

HRT mainly e.g. oestrogens | higher bioavailability than oral HRT

Question 37

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

Answer 37

3. 5-4.5 | - due to conversion of glycogen to lactic acid by lactobacillus

Question 38

Vaginal drug delivery is affected by...?

Answer 38

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

Question 39

What type of bases should pessaries be made from?

Answer 39

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

Question 40

What are 'rings' used for?

Answer 40

contraceptives

Question 41

What is a filler used in vaginal tablets and why?

Answer 41

lactose as this is a natural substrate for the vaginal microflora