Compression coating tablet is compressing a coat around a core using specially designed processes. The process involves preliminary compression of the core, which is then transferred to a large die already containing some (a half) coating material. After centralizing the core, further coating material is added and the whole compressed to form the compression-coated tablets.

There are two types of machine available for the preparation of press-coated tablet :
  1. core previously prepared on other machines
  2. compression of core and coat in one continuous circle 

Compression of Core and Coat In One Continuous Circle 

This type of machine producing compression-coated tablets in one process without previous core tablet preparation. The core and coat were prepared in the schematic sequence process :
  1. the lower-outer layer was formed by pre-compression from the upper-center punch.
  2. the lower-center punch was slid down and the upper-center punch was moved up.
  3. the powder for the core was filled and pre-compressed by the upper-center punch.
  4. the lower-outer punch was slid downward and the powder for the 2nd outer layer was filled and compressed by the upper and lower punches in which the center punches are unified with the outer punches. 

This system can be assembled onto the turn table of a rotary tableting machine and can make a dry-coated tablet in a single turn. Compression-coated tablets with a side outer coat thickness of 1 or 0.5 mm can prepared.

Source :
Novel Formulation And Processing Aspects For Compression-Coated Tablets And For The Compression Of Polymer-Coated Multiparticulates