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Inter- and Intra- Tablet Coating Variability

By Carl Wassgren

Purdue University

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Tablets are coated for a number of reasons, the most important of which is controlling the release profiles and bioavailability of the active pharmaceutical ingredient. The amount of coating on the surface of a tablet is critical to the effectiveness of the oral dosage form.

Tablets are usually coated in horizontal rotating pans with the coating sprayed onto the free surface of the tablet bed. Tablets must have a coating mass that lies within a prescribed range with very little inter- and intra-tablet coating variability.

Using the Discrete Element Method (DEM), tablet coating can be simulated on the computer. Simulation data provide the position, velocity, and orientation of each tablet within the coater, allowing accurate measurements of the time and orientation that each tablet spends exposed to the coating spray. Video-based experiments provide a validation of the simulation results.

The effect of process variables in tablet coating such as pan speed, fill level, spray pattern, spray mass flow rate can be analyzed using the DEM model. A simulated pan coater with spherical tablets used for studying inter-tablet coating variability. Continued work focuses on the intra-tablet variability,specifically the variation of coating between the caps and bands of biconvex tablets.

This video of the Pan Coating DEM modeling simulation was generated by ParticleVis.


Professor Carl Wassgren, Mechanical Engineering, Purdue University Arjun Kalbag Mechanical Engineering, Purdue University Vincent Hoon, Computer Science, Purdue University


Coating variability research sponsored by the Consortium for the Advancement of Manufacturing of Pharmaceuticals (CAMP)

Cite this work

Researchers should cite this work as follows:

  • Carl Wassgren (2007), "Inter- and Intra- Tablet Coating Variability,"

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