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Stage 2 > Pharmaceutics > Flashcards

Pharmaceutics Flashcards

1
Q

What are the critical excipients in normal aspirin?

A
  • Starch
  • lactose
  • talc
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2
Q

What are the critical excipients in dispersible aspirin?

A
  • Starch
  • Lactose
  • citric acid
  • calcium carbonate
  • Talc
  • SLS
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3
Q

What are the critical excipients in enteric coated aspirin?

A
  • Methacrylic acid-ethyl acrylate copolymer (1:1)
  • Microcrystalline cellulose
  • Lactose..
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4
Q

What are granules?

A

Aggregates of solid particles that are robust enough to withstand handling

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5
Q

What are granulations?

A

The process of producing granules

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6
Q

How does wet granulation occur?

A
  • Use a shear or fluidised bed granulator
  • Process: mix powder ingredients, then aggregate powder using a suitable binder (solution binder), then dry granules and sieve to select particle size
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7
Q

Stages of granule formulation by wet granulation

A

1- wetting and nucleation
2- consolidation and coalescence
3- attrition and breakage

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8
Q

What is intragranular bonding)

A

Bonding of particles working a molecule and it is described by the Rumpf classification.

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9
Q

What are the 5 mechanisms of bonding between granules described in the Rumpf classification?

A
  • Attractive forces between particles
  • Attractive forces between immobile films
  • Liquid bridges
  • Solid bridges
  • Mechanical interlocking
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10
Q

What are the attractive forces in the Rumpf classification?

A
  • Distant forces
  • Attractive forces between particles: van der waals (all particles) and electrostatic interactions (charged particles)
  • Attractive forces between immobile films: absorbed moisture in particle surface
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11
Q

What are the liquid bridges in Rumpf classification?

A

Capillary forces due to liquid around particles (wet granulation)

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12
Q

What are solid bridges in Rumpf classification?

A
  • Sintering of solid binder (dry granulation)
  • Re-crystallisation of liquid binder (wet granulation)
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13
Q

What is mechanical interlocking in Rumpf classification?

A
  • Shape-related bonding
  • Rough, angular particles are susceptible to mechanical interlocking
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14
Q

What are pellets?

A
  • Dense, spherical particles (5um-1.5mm)
  • Produced from granules by extrusion-spheromisation: agglomeration, extrusion, pelletisation and spheromisation
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15
Q

Similarities between pellets and granules

A
  • Can contain multiple drugs and excipients
  • Can be coated individually for modified release
  • commonly filled into capsules or pressed into tablets
  • Possible to manufacture incompatible ingredients and incorporate into a single dosage form
  • Smaller than tablets and capsules - pass through the stomach quicker
  • Do not need disintegration
  • Better able to pass through pylorus intract
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16
Q

What are the advantages of pellets compared to granules?

A
  • Greater density
  • Better flow properties
  • Lower friability
  • Narrower particle size and distribution
  • More uniform packaging
  • Smoother surface for more uniform coating
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17
Q

How does extrusion work?

A
  • Use and extruder to compress the semi solid material through a screen
  • Produces elongated, rodshaped extrudate of uniform diameter
  • Screen size and shape dictate extrudate size and shape
18
Q

What are the extrusion parameters?

A
  • Starting material properties
  • Extruder design
  • Extruder speed
  • Extruder temperature
19
Q

How does spheronisation work?

A
  • Use a spheroniser - particles are placed on a rotating friction plate, broken into smaller particles and rounded through collision with friction plate (has patterns eg crosshatching), spheroniser wall or each other
  • Produces spherical pellets
20
Q

Mechanism of spheronisation

A
  • Plastic deformation
  • Dumb-bell break-up
  • Attrition - agglomeration
21
Q

Spheronisation parameters to control:

A
  • Friction plate rotational speed
  • Charge volume/ mass
  • Retention time
22
Q

What are the critical excipients for children?

A
  • Ethanol
  • Propylene glycol
  • Parabens
  • Benzyl alcohol/ benzoates
  • Sugars/ sweeteners
23
Q

Can you give licensed phenobarbital to children?

A

No - NHS never event
Contains 38% alcohol
- tablets can be crushed and dispersed or use alcohol free liquid if possible

24
Q

What are the principles of effective drying?

A

Effective heat and mass transfer

25
Q

How does a static tray oven work?

A
  • Fan assisted ventilation and vapour removal
  • Drying rate dependant on layer thickness
  • Susceptible to solute migration
26
Q

How does a vacuum oven work?

A
  • Low pressure promotes evaporation at lower temperatures
  • Vacuum - low risk of oxidative degradation
  • Still experiences solute migration but not as much as static tray oven
27
Q

How does a microwave dryer work?

A
  • Magnetron-generated 940-2450 MHz microwaves
  • Uniform heating reduces solute migration
  • Hugh thermal efficiency: rapid drying with low thermal stress
28
Q

How does a fluidised bed dryer work?

A
  • Large drying SA - rapid drying
  • Particle movement prevents aggregation
  • Uniform heating reduces solute migration
  • Particle attrition rounds particles - better flow but more fines
29
Q

How does a spray dryer work?

A
  • Atomisation- sample sprayed into hot air stream as fine droplets
  • Drying - solvent evaporates rapidly, leaving behind solid particle
  • Collection - particles collected in a cyclone
30
Q

Why coat tablets?

A
  • Improve their friability => more robust for handling
  • Protects against oxygen, moisture, light => degrade API
  • Protects individuals => cytotoxic drugs
  • Isolate different ingredients in the same dosage form
  • Improves ease of swallowing and organoleptic properties
  • Aid identification and modify drug release profile
31
Q

What is a cellulose derivative for immediate release?

A

Cellulosic (eg hypromellose)

32
Q

What is a cellulose derivative for delayed release?

A

Cellulose acetate phthalate

33
Q

What is a cellulose derivative for extended release?

A

Ethyl cellulose or cellulose acetate

34
Q

How to identify a sugar coated tablet?

A

Usually glossy and rounded and will have to have any markings printed on

35
Q

What happens during film coating?

A
  • Atomised coating formulation sprayed through spray nozzle onto tablets/ particles
  • tablets are coated in a coating drum
  • Tablets are coated in a fluidised bed coated => coating formulation sprayed from below suspended particles (Wurster process)
36
Q

Sugar coating steps

A
  1. Sealing - waterproofing core
  2. Subcoating- provides rounding
  3. Smoothing - final rounding + smoothing
  4. Colouring
  5. Polishing
  6. Printing
37
Q

Defects with film coatings

A
  • Bridging
  • Orange peel effect
  • Core erosion
  • Cracking
  • Peeling
  • Twinning
38
Q

Defects of sugar coated tablets

A
  • Rough surface
  • Dull appearance
  • Debris from broken tablets
  • Non-uniform colour
  • Splitting - inadequate drying + swelling
  • Shellae undercoat hardens over time => slow dissolution
39
Q

What is the use of compression coating tablets?

A

Segregate two drugs in the same dosage form. So drugs can be programmed to be released at different times

40
Q

Mechanism of matrix tablets drug release

A
  • Drug diffusion => has a depletion zone
  • Matrix erosion => dissolution happens from outside in
41
Q

Excipients used in matrix tablets

A
  • Natural gums (xanthan/ guar)
  • cellulosics (HPC/ HPMC)
  • Polyethylene oxide (PEO)
  • Polymethacrylates (hydrophobic)

Stage 2 (5 decks)

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