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Gary's lecture (Pharmaceutics) > Film coating > Flashcards

Film coating Flashcards

1
Q

What are the different types of coating processes?

A
  • Film coating
  • Sugar coating
  • Compression coating
  • Gelatin coating
  • Electrostatic coating
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2
Q

What is film coating?

A

-The application of a thin layer of material to the surafce of the tablet, capsule or pellet

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3
Q

Why film coat?

A
  • Modification of dosage form apperanace
  • Blinding for clinical trials
  • Product identification
  • Phsycological reasons
  • Taste masking
  • Stability
  • Modifying drug release
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4
Q

What are the two different types of coating?

A
  • Immediate release

- Modified release (can be pH dependent or pH independent

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5
Q

What are the ideal properties of film coat?

A
  • Non-toxic
  • Soluble in appropriate solvents
  • Good film former - at appropriate temp
  • Good mechanical strength
  • Smooth Stable
  • Coherent continous coating with no holes
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6
Q

What are the common film coating ingredients?

A
  • Polymers
  • Plasticisers
  • Colourants/pigments
  • Solvent vehicle (organic vs aqueous solvents )
  • Pore-formers
  • Anti-tack agents
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7
Q

Give examples of polymers used for immediate release of film coating?

A
  • Cellulose derivatives e.g hydroxypropyl methylcellulose
  • Vinyl derivatives (PVP)
  • METHACRYLIC ACID COPOLYMERS
  • Phthalate esters
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8
Q

Hydroxypropyl methylcellulose are widely used, readily solubl ein aqeous media

  • Good film former
  • Good mechanical properties
  • Easy to apply. TRUE OR FALSE?
A

TRUE

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9
Q

PVP has limited use in film coating because of its inherent tackiness. TRUE OR FALSE?

A

TRUE

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10
Q

Water is sually the prefered solvent. TRUE OR FASLE?

A

TRUE

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11
Q

What are the ads and disads for organic solvents?

A 
Disads 
-Environmental issues 
-Safety
-Cost 
-solvent residues 
Ads 
-Sometimes preferred for moified release as they can provide a more flexible coating 
-More rapid application
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12
Q

What are plasticisers?

A

-They are usually small molecules that physically impose themselves between polymer strands

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13
Q

Plasticeers lowers the glass transition temperature of the polymer and decreases brittleness. TRUE OR FALSE?

A

TRUE

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14
Q

pIGMENTS PROVIDE AN ELEGANT COSMETIC APPEARANCE. true or false?

A

true

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15
Q

What are pigments consisted of?

A
  • Iron oxide

- Titanium dioxide

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16
Q

What is a lake pigment?

A

-A pigment manufactured by precipitating a dye with an inert binder

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17
Q

Pigments are usually water insoluble and opage and can add light protective properties to the dosage form. TRUE OR FALSE?

A

TRUE

18
Q

Pore formers are only used for water insoluble coatings. TRUE OR FALSE?

A

TRUE

19
Q

Starch cannot be used as a pore formers, TRUE OR FALSE?

A

FALSE

20
Q

Simply decsribe the process of film coating?

A
  • Film coating ia the deposition of thin uniform film of plymer formulations surrounding a tablet/capsule/pellet
  • Polymers are dissolved in organic/aqeous solution or suspended as an aqueous suspension
  • Polymer solutions/suspensions are sprayed through a nozzle uner air pressure which atomises the liquid breaking it up itno tiny droplets
  • Meanhwile, tablet cores are tumbling/fluidised in the coater and are exposed to an air inlet of high temp
  • Polymer droplets hit the tablets or pellet core, and the solvent/water evaporates
  • Dried material then remain on the surface of the tablets/pellets
  • Droplets build up until a coherent coat has been formed
21
Q

Describe the process of film formation from polymer solution?

A
  • Polymer soltuions consits of molecular chains polymers dissolved in a soltion
  • Film coating involves the concentration of the polymeric chains by evaporation
  • The polymer chains start to coalesce
  • Further gradual coalescence and polymer interdiffusion take place
  • Autohesion is the lat stage of the process
22
Q

Describe the process of film formation from suspensions?

A
  • Polymers exists as discrete particles in suspension
  • Evaporation causes the polymeric particles to come into closer proximity to each other
  • The chains start to deform
  • The particles start to coalesce, often due to capillary action
  • Further gradual coalescence and polymer interdifusion take place
  • Particles contours vanish as they cease to be discrete particles, macromolecules of adjacent particles mix through interparticular diffusion
23
Q

What is the diffusion of the polymeric chains between particles?

A

-This is a process of vsicous flow, a prerequisite of which is the existence of free volume into whcih the polymer chains can flow and intermingle

24
Q

What factors influence film coating?

A
  • Temperature
  • Molecular weight of the polymer
  • Packing and orientation of the polymer
  • Side groups/side chains
  • Flexibility of the polymer chain
  • Presence of other materials
25
Q

List the types of spray coating equipment?

A
  • Pan coater (primary process for tablets)

- Fluid bed coater (primary process for pellets/granules

26
Q

What are the critical parameters for pan coating?

A
  • Pan speed
  • Spray orientation
  • Inlet and outlet air temperature
  • Pump speed/spray rate
  • Atomising air pressure
  • Exhaust facilitites to remove dust
27
Q

What are fluid bed caoting critical parameters?

A
  • Fluidisation rate
  • Spray orientation
  • Inlet and outlet air temperature
  • Pump speed/spray rate
  • Atomising air pressure
28
Q

What is involved in wurster coating?

A

-The concept is to seperate particles from each other in a heated air stream and spray a coating onto the particles whilst they are suspended

29
Q

What si the inner area of wurster coating?

A

-Is a high velocity zone which seperates the particles and transports them past the spray nozzle, after passing the nozzle the poarticles enter the expanded area, slow down and fall back to the outer section of the fluid bed product bowl

30
Q

What are the problems with film coating?

A
  • Sticking
  • Lack of coherent coating
  • Poor elegance
  • Bridging
  • Film cracking
  • Peeling
31
Q

What is sugar coating?

A

-A succesive application of sucrose to the tablet cores

32
Q

Why is sugar coating used?

A
  • Sealing of tablet cores
  • Subcoating
  • Smoothing
  • Colouring
  • Polishing
  • Printing
33
Q

Sugar coating produces a much thicker coating than film coating and also results in shinny surface and tatse can be easily manipulated. TRUE OR FALSE?

A

TRUE

34
Q

What is compression coating?

A
  • Compressing a granular material around a tablet core, requires a special tablet press and is technically challenging
35
Q

What are the technical challenges of compression coating?

A
  • Allignment of coating metrials and route

- Sensitive to irregularities in granule size

36
Q

What is gelatin coating?

A

-Compressed tablet coated with gelatin to make capsules easier to swallow

37
Q

Gelatin can be spray coated. TRUE OR FALSE?

A

TRUE

38
Q

An alternative to spray coating gelatin onto capsules is cold shrinking of flexible gel capsules. TRUE OR FALSE?

A

TRUE

39
Q

What is electostatic coating used to create?

A

-It is based on photocopying technology used to create tablet coatings with highly distinctive patterns important to brand identification

40
Q

Electrostaic coating can also be used to load a very low dose of drugs onto tablets. TRUE OR FALSE?

A

TRUE

Gary's lecture (Pharmaceutics) (7 decks)

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