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gi tract - year one > oral powders > Flashcards

oral powders Flashcards

1
Q

powder as a dosage form meaning

A

describes a formulation in which a drug powder has been mixed with other powdered excipients to produce the final product

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2
Q

meaning of a powder as a precursor of a dosage tablet

A

can be a precursor of tablets either
- directly (powder compressed to form a tablet)
- indirectly (via granules)

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3
Q

what do granules mean as a dosage form

A

granules as dosage forms are powder particles that have been aggregated to form a larger particle 2 to 4 mm diameter

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4
Q

granules as a precursor of a dosage form

A

granules can also be an intermediate of tablet manufacturing
(typically 0.2-0.5mm)

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5
Q

advantages of powders and granules compared to tablets/capsules/liquids

A
  • more stable than liquid
  • convenient for large doses (1-5g)
  • faster dissolution rate than capsules or tablets
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6
Q

disadvantages of powders and granules compared to tablets/capsules/liquids

A
  • less convenient to carry than tablets/capsules
  • difficult to mask unpleasant taste
  • not suitable for administration of potent drugs
  • not suitable for drugs inactivated in the stomach or that can cause stomach damage
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7
Q

what powders and granules are used orally

A
  • bulk powders or granules for internal use
  • divided powders or granules (single preparation)
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8
Q

non oral administration routes of powders and granules

A
  • dusting powders for external use
  • insufflation (ear/nose/throat)
  • antibiotic syrups
  • powders for reconstitution into injections
  • dry powders inhalers
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9
Q

what can particle size affect

A
  • drug bioavailability
  • settling rate
  • possibility of obtaining homogenous mixtures
  • flowability
  • tolerability of some dosage forms
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10
Q

what factors favour powder flow

A
  • gravity
  • true density of particles
  • angle of the surface over which particles are flowing
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11
Q

what factors are against powder flow

A
  • adhesion forces (particles and container)
  • cohesion forces (particles-particles)
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12
Q

why do fine powders have higher cohesion

A

because they have higher surface/mass ratio

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13
Q

can particle shape affect the flow

A

yes

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14
Q

how does angle of repose work

A

you put powder into a funnel and pour it out into a cone shape

a low angle of repose allows good powder flow

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15
Q

what does it mean if theta is high (angle of repose)

A

the powder is cohesive

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16
Q

what does it mean if theta is low (angle of repose)

A

powder is non cohesive

17
Q

what is bulk or apparent volume

A

the volume occupied by a powder including the pores

(ie the empty gaps between particles)

18
Q

what is the tapped volume

A

the volume occupied by a powder after tapping

19
Q

what is the true volume

A

the volume occupied by a power excluding the volume occupied by the pores

20
Q

formula for bulk density

A

mass / Vbulk

21
Q

formula for true density

A

mass / Vtrue

22
Q

is the bulk density of a powder less or more than the true density

A

less

23
Q

what is the K true density

A

the bulk density

24
Q

formula for bulk density

A

mass / Vbulk

25
Q

formula of true density

A

mass / Vtrue

26
Q

formula for K

A

bulk density / true density
or
Vparticles / Vbulk

27
Q

what is porosity

A

the (%) voidage of the powder bed

28
Q

what does high porosity mean

A

water can get into particles really quickly

29
Q

what are the 3 porosity formulas

A

Vpores / Vbulk
or
(Vbulk - Vparticles) / Vbulk
or
1 - (Vparticles / Vbulk)

30
Q

what is granulation

A

the process in which homogenous mixtures of primary powder particles from larger particles called granules

31
Q

3 main advantages of granulation

A
  1. improve powder flow
  2. prevent segregation
  3. improve compaction (ie tableting)
32
Q

other reasons for granulation

A
  • reduce generation of dust (good for toxic compounds)
  • they retain flowability even after absorbing moisture
  • granules occupy less volume (good for storage)
33
Q

what are the types of granulation

A
  • wet granulation
  • dry granulation
34
Q

wet granulation process

A
  1. powders are mixed with a granulating fluid
  2. the mass is forced through. sieve
35
Q

when would wet granulation be the usually favoured choice

A

when the tablets contain larger amounts of the drugs

36
Q

chemistry behind wet granulation

A
  1. adhesion and cohesion forces in immobile films
  2. interfacial forces in mobile liquid films
  3. solid bridges (hardening binders or crystallisation of dissolved substances)
  4. attractive forces between particles
37
Q

dry granulation process

A
  1. a pressure is applied
  2. the intermediate product is broken
  3. sieving
38
Q

chemistry of dry granulation

A
  • attractive forces between solid particles
  • solid bridges formed by partial melting

gi tract - year one (25 decks)

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