Life Science Special Report December 2015

LIFE SCIENCES TABLETING AND COATING
flows with more than one million particles
in a reasonable time, making it practical for
analyzing real-world tablet manufacturing
processes such as filling, compressing/
compacting, coating and drying.
Figure 1 shows the results obtained
from a STAR-CCM+ simulation of
pre-compression in a tablet press to
determine how to overcome common
tablet defects such as capping (splitting
of the tablet’s upper cap) that often
occur as a result of entrapment of air
and migration of fine particles during the
compression process. DEM is used to
track the interaction of the particles with
each other and with the die as they are rearranged
and move into the empty spaces
during pre-compression. This simulation
offers a detailed look at the uniformity
of the granule distribution and can help
determine the optimal pre-compression
force and dwell time required to ensure
that fine particles will be locked in place
before compression starts, greatly
reducing the risk of incurring common
tablet defects during production.
DEM simulations with particle-fluid
interactions also provide realistic
solutions to assess the uniformity
of film coating thickness, a critical
parameter for tablet quality. Figure 2
depicts a simulation performed with
STAR-CCM+ for the coating process
in a fluidized bed where DEM is used
to analyze the random movement of
particles as their trajectories change
while layers of coating are applied.
Parameters such as particle velocities,
residence time and coating thickness
are monitored during the simulation.
These can be fed as objective functions
into Optimate, a module in STAR-
CCM+ that enables intelligent design,
to help identify the important factors
for equipment design (e.g. nozzle
spacing) and to determine optimal
equipment operating conditions.
STAR-CCM+ also has a novel Lagrangian
DEM simulations with
particle-fluid interactions
provide realistic solutions
to assess the uniformity
of film coating thickness,
a critical parameter for
tablet quality.
FIGURE 2: STAR-CCM+ simulation of the coating process performed in a fluidized bed
24 SPECIAL REPORT