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Solid > Tablet formation and preparation > Flashcards

Tablet formation and preparation Flashcards

1
Q

what is a tablet?

A
  • compressed solid w single/more active(s)

- circular w flat beveled or biconvex faces

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2
Q

how is a tablet prepared?

A
  • medicinal/active w or wo diluents
  • prepared by compression or moulding/3d print
  • moulding/3d print = small scale
  • compression = large scale
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3
Q

properties of oral compressed tablets?

A
  • for swallowing
  • disintegrate in stomach
  • can be enteric, modified release, effervescent etc
  • other forms: solution tablets (solvelle), hypodermic, implants
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4
Q

how to prepare effervescent tablets?

A

alkali metal carbonate/bicarbonate + organic acid (e.g. tartaric/citric acid)
- liberate CO2 in water

(1) wet fusion
- citric acid moistened, add sodium carbonate —> then granulate (form citric acid fuse powders)

(2) heat fusion: powders blended dry where citric MONOHYDRATE is used; apply heat
- water of crystallization is liberated which AIDS in GRANULATION
- water of crystallization forms the bridges

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5
Q

which method to prepare effervescent tablets is preferred?

A

(heat fusion more preferable as it minimises moisture)

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6
Q

what are the important properties tablets need to have?

A
  • exact dosage of active principle(s)
  • maximum stability
  • suitable mechanical properties
  • contain inert excipients/additives
  • suitable for its intended purpose
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7
Q

advantages of tablets?

A
  • convenient for administrating
  • delivery of accurate dose
  • small and compact
  • stable
  • easy to handle and pack
  • high production throughput
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8
Q

disadvantages of tablets?

A
  • poor compressibility (due to its elastic component)
  • poor wetting
  • slow dissolution
  • high dose
  • bitter taste/ bad odour
  • sensitive to moisture
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9
Q

what are some excipient requirements for the solid dose formulation?

A

for:

  • low dose drug - filler used
  • strength = binder used
  • bioavailability = disintegrant/wetting agent is used
  • tabletability = lubricant
  • identity = colorant used
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10
Q

what are the major excipients?

A
  • diluent/filler
  • binder/adhesive
  • disintegrant
  • lubricant
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11
Q

what are the minor excipients?

A
  • absorbent
  • wetting agent
  • stabiliser
  • colorant
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12
Q

based on functional classification of excipients, which excipients affect compaction properties?

A
  • diluents/fillers
  • binders/adhesives
  • lubricants, glidants, anti-adherents
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13
Q

based on functional classification of excipients, which excipients affect bioavailability, stability and market considerations?

A
  • disintegrant
  • lubricant
  • colours, flavours, sweeteners
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14
Q

examples of diluents/fillers; and what to take note of diluents/fillers?

A

(1) sugar
- lactose - hydrate/anhydrous forms, directly compressible (e.g. spray dried)
- sucrose based

(2) starches
- corn starch
- pregelatinized starch

(3) cellulose
- microcrystalline cellulose

(4) inorganic salts
- dicalcium phosphate

note: diluents/filler are inert, inexpensive, good flow, good compactibility

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15
Q

examples of binders/adhesives (used for strength)

A

(1) cellulose
- microcrystalline cellulose (MCC) –> high strength, low friability, self-lubricant
- dry binder

(2) modified cellulose
- HPMC

(3) synthetic polymers
- polyvinylpyrrolidone (PVP)

(4) gums
- sodium alginate, acacia, gelatin

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16
Q

examples of disintegrant

A
  • starch
    ~ swelling, wicking
  • microcrystalline cellulose (MCC)
    ~ wicking, H-bonding
  • sodium starch glycolate
    ~ swelling
  • modified cellulose gum
    ~ swelling
  • cross-linked PVP
    ~ wicking, strain recovery (memory polymer)
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17
Q

5 different mechanisms of disintegrant action

A

(1) swelling
- starch, sodium starch glycolate, modified cellulose gum
- increase in size, expand their vol

(2) wicking (capillary action)
- MCC, cross-linked PVP, starch
- intraparticulate bonds are broken

(3) strain recovery
- cross-linked PVP
- swell back to ORIGINAL state (unlike the swelling mechanism where disintegrant swells more than its original size)

(4) interruption of particle-particle bonds (H-bonding)
- MCC

(5) heat of interaction
- enthalpy changes as water enters, expansion and contraction happens

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18
Q

what do we have to ensure at least moderate dissolution of the drug?

A
  • disintegration has to occur
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19
Q

what do we have to ensure FAST dissolution of the drug?

A
  • disintegration

- and deaggregation (primary particles released) has to occur

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20
Q

types of colorant

A
  • dyes (soluble or insoluble pigment types)
  • lakes (lake pigments contain soluble dyes deposited onto carrier particles, usually metallic salts)
    ~ ensure dye dont migrate
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21
Q

purpose of colourant?

A
  • provide colour to tablet
  • often added wet, with granulation liquid
  • may be added dry (but this needs more dye to be added)
  • color used in film or sugar coating processes
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22
Q

for the definition of lubricants, what are the 3 diff types of ‘lubricant’?

A
  • glidant
  • lubricant
  • anti-adherents
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23
Q

what are glidants, and some examples?

A
  • improve flow properties of granules/powders by reducing friction BET PARTICLES, provide ‘BALL-BEARING’ effect

glidants aka flow aids (running powder)

e.g.: silicates, fused silica, starch, talc, MgSt, CaSt, Zn St

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24
Q

what are Lubricants, and some examples?

A
  • reduce the friction between granulation and die-wall (equipment) during compaction

e.g.
hydrodynamic (fluid-type) = mineral oil, paraffin

boundary (solid-type)
= water insoluble: MgSt, CaSt, stearic acid, hydrogenated vege oil, waxes

= water soluble: PEG (carbowax), Na benzoate, Na acetate, leucine, Na lauryl sulfate

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25
Q

what are anti-adherents, and some examples?

A
  • prevent sticking or adhesion of the tablet, granules or powders to the faces of the punches

e. g.:
- starch
- talc
- Mg, Ca, Zn St
- silicates derivatives
- leucine
- Na lauryl sulfate

26
Q

which materials are best for which type of ‘lubricants’ (based on the 3 types)

A

(1) stearates = excellent lubricant
(2) talc = excellent anti-adherent
(3) stearic acid = good lubricant (no glidant effect)
(4) waxes = excellent lubricant (no glidant effect)
(5) starch = excellent glidant and anti-adherent
note: poor does not mean it doesnt work

27
Q

2 different machines for tablet press?

A

(1) single punch tablet machine

(2) rotary or multi-station tablet machine

28
Q

how does the single punch tablet machine work?

A
  • lower punch in die will move down to create a die cavity for granules
  • shoe moves over die, filling the die cavity, scraping excess granules to the level of die table by moving aside
  • upper punch descends to compress granules
  • upper punch withdraws, lower punch rises to eject tablet
  • shoe shift tablet to collection chute
  • cycle repeats
29
Q

how does the rotary/multi-station tablet machine work?

A
  • dies is on a rotating platform (called turret)
  • each die has lower & upper punches
  • granules from hopper into feed frame covering a number of dies
  • lower punch descends, allow die filling to desired weight + EXCESS
  • lower punch raises to correct level, where excess granules removed
  • punches are brought together to compress granules into tablet
30
Q

what is one ‘station’ in the rotary tablet machine?

A

upper punch + lower punch + die

31
Q

What are some tableting machines to compress granules?

A
  • Tablets are formed by compression using punches of granules fed into dies
  • single punch (single station) tablet machine
  • rotary (multiple station) tablet machine
32
Q

What are the two terms important in compaction forces?

What is the formula for strain?

A

Stress: applied force to produce a deformation

Deformation: change in the relative positions of different parts of body, expressed as STRAIN which is a change in length per unit length or volume per unit volume

Strain (L0 - L)/L0 = change in L / original length

33
Q

What is the Hooke’s Law and what is the relationship between the variables in the equation?

A

sigma = Y X e

Y = modulus of elasticity or Young’s modulus

sigma (y) = yield stress, stress at the elastic limit

e = axial strain

For a given load:

smaller the Young’s Modulus, more strain –> greater the amount of elastic recovery and maybe lower compact strength due to structural failure

34
Q

How to read a stress-strain relationship for consolidation and bond formation?

A

x axis: displacement (axial strain, e)
y axis: force (axial stress, sigma)

from 0 to sigma (y) (y axis), the slope is linear - ELASTIC. elastic limit has reached at sigma (y)

But beyond sigma (y), VISCO-ELASTIC (+ PLASTIC) occurs.
if stress if removed, the axial stress can go back to zero.

So, from elastic to visco-elastic (+plastic) portion, total recovery is possible

If it is beyond the yield point (fracture, break), deformation occurs (irreversible)

35
Q

How does the compaction cycle look like?

A

Bond making (loading): repacking –> elastic deformation –> plastic deformation –> brittle fracture –> visco-elastic deformation

Bond breaking (unloading): Elastic recovery (unloading): elastic recovery –> visco-elastic recovery

36
Q

What are the events in die during compactive cycle?

A
  1. Die filling
  2. Pre-compression: particle rearrangement
  3. Main compression: fragmentation, plastic deformation, elastic deformation
  4. Ejection: elastic recovery

Consolidation state: Bulk density –> Tap density –> Compact –> and becomes tablet

37
Q

What are some tableting terminologies (there are 3)?

A

Tabletability: capacity of a powdered material to be made into a tablet of specified strength under the effect of compression pressure

Compressibility of a material: ability to undergo volume reduction when subjected to an applied pressure

Compactibility: ability of a material to produce tablets with sufficient strength under the effect of densification

38
Q

What are the relationships btw compressibility, tabletability and compactability?

A

For tabletability: as compression press (compaction pressure) increases, tensile strength inc (upward slope graph)

For compactability: as porosity inc (solid fraction), tensile strength decreases (downward slope)

For compressibility: as compression press (compaction pressure) increases, Porosity (solid fraction) decreases (downward slope)

pg35 for the graphs

39
Q

What do we need to better understand the process understanding?

A

triangle cycle: compressibility, tabletability and compactability

Material properties:

  • tablet press compaction cycle
  • lubrication
  • tooling / tablet design

–> proceeds to –>

Tablet microstructure

–> proceeds to –>

Tablet mechanical properties - tablet hardness, friability, dissolution

40
Q

Tablet formation requires _______

A

tabletability, i.e. compaction forces can be translated to mechanically strong compacts

Thus, properties of components to form tablets are critical for the formulation requirements for tableting!

41
Q

What are attributes of a “good tablet” (there are 4)?

A
  • contain correct amt of active(s)
  • must possess good mechanical properties: hardness, friability
  • chemically stable, and
  • correct biopharmaceutical pprty: content, disintegration, dissolution

granules for tableting must confer the necessary requisites, and thus the judicious choice of excipients is essential

Need to ensure correct brittle-plastic balance, flow, moisture content, granule porosity, lubrication, etc.

42
Q

Mechanical strength of tablets depends on?

A
  • particle size, distribution, shape
  • granule porosity
  • moisture content
  • fragmentation and visco-elastic deformation
  • applied load (compaction force)
  • time of loading (Strain rate sensitivity)
  • time of unloading (strain rate sensitivity)
  • elastic stress release upon ejection
43
Q

What are the material requirements for tableting in mechanical strength of tablets?

A
  • Ideal brittle-plastic balance for good compressibility
  • adequate granule porosity for compressibility
  • sufficient moisture content for correct compressibility
  • good powder flow for ideal tabletability
  • correct level of lubrication for good compactibility
44
Q

What are the causes of capping?

A
  • air entrapment
  • mechanism of volume reduction
  • compression speed
  • viscoelastic recovery
  • stress and density distribution
  • internal shear stress
45
Q

What are the remedies for capping?

A
  • lower compression force
  • reduction compression speed
  • decreasing ejection path in the die
  • tool design change
  • extend dwell time
46
Q

What to take note of brittle-plastic balance?

A

Under compressive forces, plastic material will deform irreversibly whereas brittle or fragmenting material will deform by breaking down into small fragments

47
Q

How is the compact strength like for plastic and brittle material?

A

Plastic: stronger
Brittle: Weaker

48
Q

How is capping propensity like for plastic and brittle material?

A

plastic: higher
brittle: lower

49
Q

How is the turret speed sensitivity (tableting speed) like for plastic and brittle material?

A

Plastic: higher
Brittle: Lower

50
Q

How is lubricant sensitivity (mixing time of amt) like for plastic and brittle material?

A

Plastic: higher
Brittle: Lower

51
Q

How do we classify tabletability?

A

Deformation behaviour: plastic, elastic, or brittle
Looks at bond area
Plastic is normally high bond area
Elastic/brittle is normally low bond area

  • Low compactability (low surface energy compounds and weak bonds formed) –> bond strength is low
  • High compactability (high surface energy compounds and strong bonds formed) –> bond strength is high

note: high bond area = plastic
low bond area = elastic

  1. When bond area is high and bond strength is high –> high tabletability
  2. When bond area is high and bond strength is low –> high or low tabletability
  3. When bond area is low and bond strength is low –> low tabletability
  4. When bond area is low and bond strength is high –> low or high tabletability
52
Q

How to improve plasticity by granulation?

A

Powder at first –> API (elastic) + Binder (plastic) –> wet granulation (provides plasticity) –> becomes granules

53
Q

What are some segregation challenges in compaction?

A
  • trying to achieve good content uniformity
    ~ substantial risk of segregation at different steps of feeding process from hopper to feeder (Transferring process)
    ~ tendency of tablet feed to segregate inc with large differences in form, size and/or density of the particles/granules

Powder flow with segregation is critical during tableting

Flow must be free and uniform, into the die to ensure:

  • tablet weight uniformity
  • tablets with consistent and reproducible properties

Must always ensure good feed flow and thus, powder flowability

(I wrote: To do granulation to improve flow w/o segregation
- as in granulation lec; granulation is done as it can improve flowability, reduce segregation tendency, improve compactibility)

54
Q

why is continuous manufacturing popular/preferred?

A
  • cost reduction - overall & unit product cost
  • efficient & robust process development
  • improved product quality
  • flexibility
  • reduced environmental impact
55
Q

why is the CM process combination flexible?

A
  • multiple processes are possible
    e. g. after blending can do diff types of granulation or pelletisation
    e. g. after blending can go straight to compression
56
Q

how does CM work?

A

(1) materials are preblended with various excipients
(2) granulating liquid is added
(3) drying (segmented dryers) is done
(4) PAT (process analytical technology) is done
(5) granulating –> tableting done
(6) coating done

  • processes are repeated
57
Q

what is the compact CM facility used for?

A
  • for direct compression, wet and dry granulation

- facility is portable

58
Q

what does the CM granulation skid consists of?

A
  • hopper with preblended feed powder
  • twin-screw extruder + granulation liquid = granulation unit
  • segmented dryer unit
  • granule conditioning unit
59
Q

Fluid bed, high shear, roller compaction - which method has the best compressibility?

A

Fluid bed&raquo_space; high shear&raquo_space; roller compaction

Air spaces removed; shear involved

Roller compact - particles already precompacted

Fluid bed granules snowflake formation - the best compressibility

60
Q

What kind of deformation area refers to low bond area?

A

Elastic and/or brittle

61
Q

What kind of deformation area refers to high bond area?

A

Plastic

Solid (16 decks)

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