Tablet coating increase the tablet elegance and sometimes protect from stomach acids. Appropriate selection of coating materials can save both tablets & process time. Here's a comparison between HPMC based coating materials & PVA based coating materials -


1.

  • HPMC based coating materials contain solid content max 15%.
  • PVA based coating materials contain solid content max 20%.


2.

  • HPMC based coating materials produce film of higher strength than PVA based.
  • PVA based coating is low viscous and low molecular weight coating solution and form thin film.


3.

  • PVA based coating materials produce 3 times higher film adhesion.
  • HPMC based coating is less glossy than PVA/Na-CMC based coating


4.

  • PVA based coating materials exhibit comparatively very low viscosity even with high solid content  than HPMC based coating.
  • PVA based coating materials exhibit high atomization, low chance of spray gun clogging, smooth pumping, higher solid delivery to tablets, faster film adhesion and shorter process time than HPMC based coating.


5.

  • HPMC based coating: increased pan speed cause higher defects in tablets.
  • PVA based coating: increased pan speed cause finer tablets.
  • PVA based coating produce higher degree of slip, less frictional force, more efficient mixing, less attrition and lower defects.


6. 

  • PVA based coating materials is suitable for tablets with lower hardness/ friable tablets.