Tablet Coating

1
Tablet Coating

• Why coat tablets?
• Types of coatings
• sugar coating
• film coating
• press coating (compression coating)

2
Sugar Coating

• stages involved
• sealing of tablet core
• subcoating
• smoothing
• colouring
• polishing
• printing

3
Film Coating

• involves spraying a solution of polymer
  pigments plasticizers onto a rotated, mixed
  tablet bed
• forms a thin, uniform film on tablet surface
• materials
• polymers
• solvents
• plasticizers
• colorants

4
Film Formation
latex particles dispersed in aqueous phase
formation of thin film with water evaporation
through film
continuous film
5
Coating Process

• coating pans

6
Coating Process

• fluid beds

7
Important Processing Parameters

• inlet and bed temperatures
• relative humidity
• atomization air pressure
• liquid spray rate
• droplet size
• drying time

8
Coating Problems

• picking/chipping
• roughness
• sticking
• film cracking/peeling

9
Normal Coating
10
Enteric-coated

• coating resists dissolution or disruption in
  stomach but not in intestines
• used for drugs that are unstable, irritating to
  stomach

11
Enteric Coating
12
Press Coating

• use of compression to form coat around a
  pre-formed core
• used mainly to separate chemically incompatible
  materials
• also dual release patterns possible