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medicine sem2 > methods of formulation 2 > Flashcards

methods of formulation 2 Flashcards

1
Q

How are insoluble particles dealt with in the lungs?

A

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

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2
Q

Give 3 drugs given by the lungs for systemic delivery:

A
  • sodium cromoglicate (hay fever)
  • isoprenaline (bradycardia)
  • ergotamine (migraines)
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3
Q

What is the optimal particle size for aerosols?

A

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

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4
Q

aerosols are lyophobic colloids, so how are they prepared?

A

by dispersion or condensation

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5
Q

How are aerosols administered?

A

by inhalers or nebulisers

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6
Q

What is the difference between an MDI and a DPI?

A 
MDI = generate an aerosol when deployed 
DPI = contain capsules/blisters loaded with drug particles
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7
Q

What are nebulisers used for?

A

treatment of COPD, CF, asthma, antibiotics, opioids

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8
Q

What is local nasal drug delivery used to treat?

A

nasal congestion, infection, hayfever

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9
Q

What is systemic nasal drug delivery used to treat?

A

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

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10
Q

What particle size is good for nasal drug delivery?

A

5-10um

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11
Q

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

A

epithelium of the nasal turbinates

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12
Q

How do lipophilic drugs cross the epithelium of the nose?

A

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

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13
Q

What indication does PenFent have that is good?

A

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

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14
Q

What are the advantages of rectal drug delivery?

A
  • 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
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15
Q

What are the disadvantages of rectal drug delivery?

A
  • 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%)
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16
Q

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

A

all have goblet cells which release mucus

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17
Q

What is the pH of the rectum?

A

around 7.5 (more alkaline in children)

18
Q

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

A

As the rectum doesn’t have buffering capacity

19
Q

How does rectal delivery avoid first pass metabolism?

A

By passing straight to the vena cava

20
Q

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

A
  • limited SA for absorption

- reduced fluid volume, affecting drug dissolution

21
Q

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

A

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

22
Q

depending on the vehicle, a suppository will either…

A

melt on the mucous layer or dissolve in the rectal fluid

23
Q

How much do rectal suppositories weigh?

A

1-4g

24
Q

What are the 2 types of bases used in suppositories?

A
  1. water soluble bases (used less)
  2. glyceride type fatty acids (natural/synthetic oils such as triglycerides, saturated fatty acids, waxes, fatty alcohols )
25
Q

Whichever suppository base is used, they should all…?

A
  • 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
Q

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

A

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

27
Q

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

A

yes - prevents sedimentation, smaller particles means faster dissolution rate

28
Q

In what 3 ways are suppositories formed?

A
  • hand rolling (small scale)
  • compression moulding (semi automated)
  • fusion moulding (semi-automated)
29
Q

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

A

slows down drug release (as particles are trapped)

- colloidal silicon oxide, aluminium monostearate

30
Q

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

A

3.5g and contain drug particles of 25um

31
Q

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

A

haemorrhoids

32
Q

Why are rectal tablets not used often?

A

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

33
Q

Rectal tablets which release CO2 can be useful, why?

A

the gas released, stimulates defecation

34
Q

Why are enemas good?

A

solutions/emulsions/suspensions

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

35
Q

What are the local uses of vaginal drug delivery?

A

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

36
Q

What are the systemic uses of vaginal drug delivery?

A

HRT mainly e.g. oestrogens

higher bioavailability than oral HRT

37
Q

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

A
  1. 5-4.5

- due to conversion of glycogen to lactic acid by lactobacillus

38
Q

Vaginal drug delivery is affected by…?

A 
menopause
pregnancy
phase of menstrual cycle
candida infection 
- NOT HPV infection
39
Q

What type of bases should pessaries be made from?

A

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

40
Q

What are ‘rings’ used for?

A

contraceptives

41
Q

What is a filler used in vaginal tablets and why?

A

lactose as this is a natural substrate for the vaginal microflora

medicine sem2 (7 decks)

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