Pharmaceutics-Film and Sugar Coating Methods

Question 1

what are the types of coatings available?

Answer 1

• film coating
• sugar coating
• compression coating

Question 2

what are the advantages to using film-coating?

Answer 2

• Protection of dosage form.
• Wide range of coating excipients to suit desired release
  profile.
• Single-step process easy to automate.
• Thin coating adds minimum weight.
• IR coatings do not affect disintegration or dissolution.
• Maintains original tablet shape and surface features (e.g.
  embossing, break marks).

Question 3

what are the disadvantages ti using film coating?

Answer 3

• High cost and footprint.

- Use of organic solvents may pose potential hazards.

Question 4

what equipments are used to film coat tablets/particles?

Answer 4

1. coating drum (for tablets and may be perforated to allow air to flow through for drying)
2. fluidised bed (for particles)
3. spray nozzle (to atomise the coating liquid

Question 5

what excipients are used in the coating liquid formulation?

Answer 5

1. film-forming polymer
2. solvents
3. plasticisers
4. colourants
5. wetting agents
6. anti-tack

Question 6

what are the types of film coatings?

Answer 6

release profiles (IR, ER, DR)

Question 7

what dictates the release profile, hence the type of film coating?

Answer 7

-polymer type dictates the release profile

Question 8

what are some film-coating defects?

Answer 8

1. bridging
2. orange peel effect
3. core erosion
4. cracking
5. peeling
6. twinning

Question 9

what is bridging?

Answer 9

when the film coating makes the intended marking less clear

Question 10

what is the orange peel effect?

Answer 10

uneven spreading of the film coating liquid

Question 11

what causes the orange peel effect?

Answer 11

• Incorrect atomisation settings or spray rate,
• coating liquid too viscous,
• drying too rapid,
• overly porous tablet core.

Question 12

what causes bridging?

Answer 12

• Film shrinkage on drying overcomes film adhesion to tablet

- pulling film away from tablet surface.

Question 13

what is core erosion?

Answer 13

dissolution and disfigurement of tablet surface

Question 14

what causes core erosion?

Answer 14

• Over-exposure to coating liquid,
• soft tablets
• inadequate drying.

Question 15

what is cracking?

Answer 15

when there’s a fissure in film coating

Question 16

what causes cracking?

Answer 16

• Insufficient mechanical strength of coating
• insufficient plasticiser
• thermal expansion of tablet.

Question 17

what is peeling?

Answer 17

when the film coating lifts off the tablet surface

Question 18

what causes peeling?

Answer 18

• Insufficient film-tablet adhesion due to

hydrophobic core material.

Question 19

what is twinning?

Answer 19

when two tablets sick together along edges (more prone in caplets)

Question 20

what causes twinning?

Answer 20

• coating liquid too viscous

- ineffective drying

Question 21

what are advantages of sugar coating?

Answer 21

• Inexpensive.

- Safe/accepted raw materials.

Question 22

what are some disadvantages of sugar coating?

Answer 22

• Significant weight gain (30–50%).
• Water-soluble coat, immediate release only.
• Multi-step process.
• Not easily automated, requires intensive operator attention.
• Alters shape of tablets/particles.
• Embossing (raising) not possible.

Question 23

explain the process of sugar coating?

Answer 23

1. sealing -waterproof core with 1 or more layers of shellac/polymer
2. sub-coating - apply sucrose syrup for round shape
3. smoothing - again with sucrose syrup
4. colouring - thin syrup coats containing colourants
5. polishing - apply wax for glossy appearance
6. printing - text/symbols in indelible ink for product identification

Question 24

what are the defects of sugar coatings?

Answer 24

• Rough surface.
• Dull appearance.
• Debris from broken tablets.
• Non-uniform colour.
• Splitting due to inadequate drying and swelling.
• Shellac undercoat hardens over time, slow dissolution of
  aged tablets.

Question 25

what process is used to apply compressed coating?

Answer 25

a dry process by which the coating is applied as a dry powder unlike for film and sugar where it is a wet coating
-uses secondary compression on a specialised tablet press

Question 26

importance of compression coating?

Answer 26

helps to release drugs at different times

Question 27

what factors of a compression coating affect drug release rate?

Answer 27

• the material of choice

- the coating thickness