Pharmaceutics-Film and Sugar Coating Methods Flashcards
what are the types of coatings available?
- film coating
- sugar coating
- compression coating
what are the advantages to using film-coating?
- 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).
what are the disadvantages ti using film coating?
- High cost and footprint.
- Use of organic solvents may pose potential hazards.
what equipments are used to film coat tablets/particles?
- coating drum (for tablets and may be perforated to allow air to flow through for drying)
- fluidised bed (for particles)
- spray nozzle (to atomise the coating liquid
what excipients are used in the coating liquid formulation?
- film-forming polymer
- solvents
- plasticisers
- colourants
- wetting agents
- anti-tack
what are the types of film coatings?
release profiles (IR, ER, DR)
what dictates the release profile, hence the type of film coating?
-polymer type dictates the release profile
what are some film-coating defects?
- bridging
- orange peel effect
- core erosion
- cracking
- peeling
- twinning
what is bridging?
when the film coating makes the intended marking less clear
what is the orange peel effect?
uneven spreading of the film coating liquid
what causes the orange peel effect?
- Incorrect atomisation settings or spray rate,
- coating liquid too viscous,
- drying too rapid,
- overly porous tablet core.
what causes bridging?
- Film shrinkage on drying overcomes film adhesion to tablet
- pulling film away from tablet surface.
what is core erosion?
dissolution and disfigurement of tablet surface
what causes core erosion?
- Over-exposure to coating liquid,
- soft tablets
- inadequate drying.
what is cracking?
when there’s a fissure in film coating
what causes cracking?
- Insufficient mechanical strength of coating
- insufficient plasticiser
- thermal expansion of tablet.
what is peeling?
when the film coating lifts off the tablet surface
what causes peeling?
- Insufficient film-tablet adhesion due to
hydrophobic core material.
what is twinning?
when two tablets sick together along edges (more prone in caplets)
what causes twinning?
- coating liquid too viscous
- ineffective drying
what are advantages of sugar coating?
- Inexpensive.
- Safe/accepted raw materials.
what are some disadvantages of sugar coating?
- 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.
explain the process of sugar coating?
- sealing -waterproof core with 1 or more layers of shellac/polymer
- sub-coating - apply sucrose syrup for round shape
- smoothing - again with sucrose syrup
- colouring - thin syrup coats containing colourants
- polishing - apply wax for glossy appearance
- printing - text/symbols in indelible ink for product identification
what are the defects of sugar coatings?
- 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.
what process is used to apply compressed coating?
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
importance of compression coating?
helps to release drugs at different times
what factors of a compression coating affect drug release rate?
- the material of choice
- the coating thickness