Scuffing of Film-coated Tablets

Scuffing involves the generation of gray-to-black marks on the surface of white (or lightly colored) film-coated tablets, thought to be an abrasion interaction between titanium dioxide in the coating and the stainless steel pan walls

ISSUE CAUSES RECOMMENDATIONS
Tablet Core While tablet cores tend to not play a significant role in the scuffing process, the larger the tablets and the denser the core formulation, the greater the likelihood that tablet sliding will occur; this can exacerbate the problem.
  • Avoid the use of high-density mineral fillers such as calcium carbonate, dicalcium phosphate or calcium sulfate.
Large tablets that have deep side walls, and have elongated shapes (such as capsule-shaped tablets), can “lock” together (like bricks in a brick wall), causing them to slide en masse, thus increasing the chances of scuffing effects. Learn more.
  • Change tablet shape.
Coating Formulation While it has been reported (Rowley, Tablets & Capsules, April 2012; Ogasaware, Steffinino & Cunningham, AAPS Poster, Annual Meeting 2008) that the type of coating formulation used rarely has an impact on scuffing problems, there are several issues relating to coating formulations that can be implicated, including the use of coating formulations with high TiO2 content (especially white and pastel colors), which can be more problematic.
  • Change the color, or reduce the level of TiO2 (Ogasaware, Steffinino & Cunningham, AAPS Poster, Annual Meeting 2008).
The type of coating formulation can be problematic.
  • Use Aquarius Preferred HSP film coating formulations. Learn more.
Coating Process The longer the duration of the coating process, the greater the opportunity for coated tablets to interact with the metal surfaces of the coating pan, and hence the greater the chance that scuffing will occur.
  • Shorten the duration of the coating process.

Pan speed can cause tablets to slide in the coating pan.

  • Increase pan speed.

Under filling of the coating pan can increase the risk of tablet sliding.

  • Increase pan filling.

Thermodynamic conditions.

  • Employ a cooler process (lower processing temperatures and/or faster spray rates).

Coating Equipment

  • Ensure that pan surfaces are thoroughly cleaned.

  • Passivate the stainless steel surfaces of the coating pan that  contact with tablets.
  • Spray a thin coating of HPMC onto the exposed surfaces of the pan walls.