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PHA111 > Excipients > Flashcards

Excipients Flashcards

1
Q

are excipients therapeutically active / unactive?

A

therapeutically unactive

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2
Q

what do excipients control the behaviour of?

A

dosage form

e.g. can affect bioavailability

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3
Q

what are the main properties of tablets?

A
  • facilitate administration
  • promote consistent drug release/bioavailability
  • protect drug against degradation
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4
Q

examples of tablet excipients?

A
  • diluents/bulking agents
  • lubricants
  • binding agents
  • glidants
  • disintegrating agents
  • dyes and flavouring agents
  • coatings
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5
Q

why are diluents/ bulking agents used?

A

added to make adequate sized tablets

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6
Q

what is the most common bulking agent?

A

alpha lactose monohydrate

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7
Q

properties of diluents/bulking agents?

A
  • pleasant tase
  • good solubility / dissolution
  • low hygroscopicity
  • inert
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8
Q

what is spray dried lactose used for?

A

direct compression

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9
Q

what is microcrystalline cellulose good for?

A

direct compression

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10
Q

what is mannitol used for?

A

chewing tablets

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11
Q

what is the function of lubricants?

A
  • prevent powder/metal adherence
  • ensures smooth ejection from die
  • enhances flow properties
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12
Q

example of a lubricant?

A

magnesium stearate (up to 1% w/w - hydrophobic)

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13
Q

disadvantage of lubricants?

A
  • prolongs disintegration time
  • -> reduces drug dissolution
  • reduces tablet strength
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14
Q

is sodium stearyl fumarate hydrophilic / hydrophobic?

A

hydrophilic

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15
Q

function of binding agents?

A

adhesives to bind particles together during granulation / as solution for wet granulation

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16
Q

examples of binding agents?

A
  • starch

- PVP (polyvinylpyrrolidine)

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17
Q

function of glidants?

A
  • improve flow of powders/granules

- reduces inter particulate friction - smooths surface irregularities

18
Q

example of glidant?

A

colloidal silica

19
Q

function of disintegrating agents?

A
  • cause tablets to disintegrate —> inc surface area
20
Q

what do disintegrating agents do when in contact with water?

A
  • swell

- burst open in water

21
Q

examples of disintegrating agents?

A
  • starch

- croscarmellose sodium

22
Q

some disintegrating agents work by capillary action, which involves drawing liquid up through pores.

what does this do?

A

disrupts bonds between particles

e.g. pregelatinised starch

23
Q

lyophilised tablets take how long to disintegrate (orodispersible tablets)?

A

5 seconds

mainly sucrose

24
Q

what do coatings include?

A
  • film / sugar coat
  • enteric coatings (e.g. cellulose acetate phthalate / polymers- eudragits)
  • polymers for M/R release e.g. HPMC and xanthan gum
25
Q

what are the excipients used for liquid prep?

A
  • water
  • water miscible co solvents
  • buffers
  • antimicrobial agents
  • anti-oxidants
  • wetting agents
  • antifoaming agents
  • thickening agents
  • sweetening agents
  • flavouring agents
  • humectants
26
Q

water

A
  • most used
  • physiologically non toxic and compatible
  • good dissolver
27
Q

what are the disadvantages to using water?

A
  • supports microbial growth

- care with drugs prone to hydrolysis

28
Q

water miscible co solvents

A
  • enhance solubility, taste and stability

- e.g propylene glycol, glycerol and ethanol

29
Q

buffers

A
  • control pH
  • enables physiological compatibility, microbiological and chemical stability and solubility
  • OR INSOLUBILITY if taste = issue
30
Q

antimicrobial agents

A
  • are preservatives

- prevent growth of opportunistic microbes (from excipients / externally introduced)

31
Q

anti-oxidants

A
  • control oxidation of drug, preservative and excipients

- conc decreases with time since oxidises first

32
Q

wetting agents

A
  • decrease interfacial tension
  • e.g. surfactants (cetrimide, SLS)
  • hydrophilic colloids (cellulose derivatives, tragacanth - also acts as suspending agent)
33
Q

antifoaming agents

A

e.g. simethicone

34
Q

thickening agents

A
  • stabilise suspensions
  • give high viscosity (mostly thixotropic)
    e. g. methylcellulose
35
Q

sweetening agents

A

natural - sucrose

artificial - saccharin

36
Q

flavouring agents

A

natural - peppermint

artificial - butterscotch

37
Q

humectants

A
  • hygroscopic excipients for external prep (suspensions, emulsions) e.g. glycerol, PEGs
  • reduce evaporation of water / aq vehicle —> prevents drying after application AND during product life
38
Q

what is the best lubricant?

A

magnesium stearate

39
Q

how long can sugars take to disintegrate?

A

up to an hour

40
Q

substances that contain more magnesium stearate means what..

A

higher disintegration time

41
Q

if a tablet is brittle what happens?

A

will fragment and break

e.g. lactose

PHA111 (30 decks)

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