There are a lot of common tablet problems arise during compression and coating. Some of them discuss below- 


Mottling

Definition: 'Mottling' is a tablet problem where unequal distribution of color occurs on a tablet, with light or dark spots standing out in an otherwise uniform surface.


Reasons: 

  • A colored drug used along with colorless or white-colored excipients.
  • A dye migrates to the surface of granulation while drying.
  • Improper mixing of dye, especially during 'Direct Compression'.
  • Improper mixing of a colored binder solution.


Remedies:

  • Use appropriate colorants.
  • Use a smaller particle size of API and Excipients.
  • Mix properly and reduce size if it is of a larger size to prevent segregation.



Color Variation during coating

Color variation is also a tablet problem usually arise during coating. 


Reasons:

  • Improper mixing
  • Uneven spray pattern
  • Insufficient coating


 Remedies:

  • Proper mixing
  • Uniform spray
  • Optimize coating formulation


Orange Peel

A tablet problem which result a bumpy or orange peel effect on coating before drying.


Reasons:

  • Impaired spreading by rapid rate of drying
  • High viscosity of solution


Remedies:

  • Thinning of coating solution