SUGAR-COATING PROCESS AND BAFFLES THEREFOR
FIELD OF THE INVENTION
This invention relates to sugar coating processes, and baffles for use in
coating apparati.
BACKGROUND OF THE INVENTION
The sugar coating process originated within the confectionery industry, it is
perhaps one of the oldest pharmaceutical processes for taste masking. Although
sugar coating of tablets is less frequently employed, probably because of its level of
coating expertise needed to achieve consistent elegant products, it has been
retained by many companies worldwide because of many factors including, for
example, inexpensive and readily available raw materials, global acceptance of raw
materials (with exception of colors), highly elegant appearance of coaled tablets, and
suitable lower temperature for aqueous process and processing for heat sensitive
products.
Although complex, the "basic" application procedures for sugar coating
involve the following steps; 1) maintaining appropriate coating pan conditions
throughout operations, such as air flow rate(s), humidity conditions, and bed
temperature(s); 2) consistent multiple applications of an appropriate or titrated
volume of coating solution/suspension to a cascading/flowing bed of tablets; 3) an
appropriate tumbling jog cycle to allow distribution of the coating solution/suspension
uniformly across the surface of each tablet in the charge; and 4) drying of each
application of the coating solution/suspension to assure uniform distribution prior to
the next application{s).
Factors for coating unifonmity in the sugar coating process include, for
example, application of sufficient coating medium to spread across the surface of
every tablet in the batch, sufficiently fluidity of the coating medium to permit
spreading across the surface of every tablet in the batch, and appropriate dimensions
and shape of the coating pan and baffles to provide adequate mixing and avoid
"dead spots"' or, conversely, "wet spots."
Suitable baffle designs exhibiting excellent mixing and coating uniformity
would thus be highly desirable for coating pharmaceutical formulations.

SUMMARY OF THE INVENTION
The present invention provides a baffle comprising: a first side comprising a
top edge, a bottom edge, and a lateral edge, wherein the first side is flat, and wherein
the top edge and bottom edge converge to form a first side tip that is distal to the
lateral edge; and a second side comprising a top edge, a bottom edge, and a lateral
edge, wherein the second side is curved, and wherein the top edge and bottom edge
converge to form a second side tip that is distal to the lateral edge. The first side and
second side of the baffle are joined at each of the top edges. In addition, joining of
the first and second sides forms an internal angle of no less than about 45° to no
greater than about 120°. Further, the first side tip and second side tip converge to
form a single tip. In some embodiments, the first side and second side are joined
seamlessly at the top edges.
Also provided in accordance with the present invention are coating pans
comprising: a cylindrical surface for receiving a pharmaceutical formulation; an outer
wall in contact with one end of the cylindrical surface; an inner wall in contact with the
other end of the cylindrical surface; and at least one baffle as described above. The
lateral edges of the first and second sides forming the baffle contact the inner or
outer wall of the coating pan. In addition, the bottom edges of the first and second
sides forming the baffle contact the cylindrical surface of the coating pan. In some
embodiments, the single tip of at least one of the baffles in the coating pan does not
extend the entire width of the cylindrical surface. In some embodiments, the coating
pan comprises at least two baffles which are oriented in the opposite direction
Also provided in accordance with the present invention are coating apparati
comprising a coating pan described above.
Also provided in accordance with the present invention are methods of
manufacturing a baffle comprising creating a template of the baffle, and cutting and
shaping a baffle material based upon the template. In some embodiments, the
contour of the coating pan is used to create the baffle template, in some
embodiments, the template comprises a height of no less than about 1 inch and no
greater than about 8 inches, and comprises a length that is no less than about 0.1
inch and no greater than about 4 inches less than the width of the cylindrical surface
of the coating pan. In some embodiments, the internal angle of the baffle is about

90°. In some embodiments, the baffle material is Teilon which is shaped with a
lathe.
Also provided in accordance with the present invention are methods of
coating a pharmaceutical formulation comprising introducing the pharmaceutical
formulation and coating composition into a coating pan described herein and rotating
the coating pan. In some embodiments, the coaling composition comprises at least
one sugar.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows a representative baffle (10) of the invention.
Figure 2 shows a cross-section of a representative baffle (10) of the invention.
Figure 3 shows a representative baffle (10) within a representative coating
pan (50) of the invention.
Figure 4 shows placement of the baffles (10) in regard to the cylindrical
surface (52) of a representative coating pan (50) of the invention.
Figure 5 shows weight variations at different weight gain levels using different
baffle designs.
Figure 6 shows weight variations of coated tablets at different weight gain
levels using different baffles.
Figure 7 shows content uniformity of MPA of coated tablets at 100% weight
gain level using different baffles.
Figure 8 shows weight variations of coated tablets at different weight gain
levels using different baffles coated in GCX1000 (the legend mirrors the order of the
bars of the graph).
Figure 9 shows content uniformity of MPA of coated tablets at 100% weight
gain level using different baffles coated in GCX1000.
Figure 10 shows Baffle A installed in a pan
Figure 11 shows Baffle B installed in a pan.
Figure 12 shows Baffle C installed in a pan.
Figure 13 shows Baffle B and Baffle D installed in a pan, wherein Baffle D is
the baffle closest to the viewer.
Figure 14 shows two views of Baffle E installed in a pan.
Figure 15 shows Baffle F installed in a pan.

Figure 16 shows Baffle G installed in a pan. Baffle G is an embodinnent of the
present invention.
Figure 17 shows Baffle H installed in a pan.
Figure 18 shows two views of Baffle I installed in a pan.
DETAILED DESCRIPTION
In some embodiments, the invention provides a baffle (10). The baffle can be
used, for example, in a variety of coating pans within any coating apparati for coating
pharmaceutical formulations. Suitable formulations that can be coated using the
baffle(s) of the invention include, but are not limited to, tablets and the like
Referring to Figure 1, the baffle (10) comprises a first side (20) and a second
side (30). The first side (20) comprises three edges: a top edge (22), a bottom edge
(24), and a lateral edge (26). The top edge (22) and bottom edge (24) of the first side
(20) converge to form a first side tip (28) distal to the lateral edge (26) of the first side
(20). In some embodiments, the first side (20) is flat (planar) and has no curvature.
Also referring to Figure 1, the second side (30) also comprises three edges: a
top edge (32), a bottom edge (34). and a lateral edge (36). The top edge (32) and
bottom edge (34) of the second side (30) converge to form a second side tip (38)
distal to the lateral edge (36) of the second side (30). In some embodiments, the
second side (30) is curved in a convex manner from the lateral edge (36) to the
second side tip (38).
Still referring to Figure 1, the first side (20) and second side (30) are joined at
each of the respective fop edges (22) and (32), thus forming a single baffle unit (10)
with the first side tip (28) converging with the second side tip (38). In some
embodiments, the joining of the sides (20) and (30) can be accomplished by one or
more fasteners (not shown) commonly used in the art. For example, the fasteners
can be mechanical fasteners such as bolts, screws, hinges, rivets, and the like. In
addition, the fasteners can include chemical agents such as glues, epoxys, and the
like. Alternately, the joint formed by the first and second sides (20) and (30) can be
seamless. Thus, in some embodiments, the first and second sides (20) and (30) can
be manufactured as a single integral unit In some embodiments, the edge (22/32)
formed by the joining of the respective top edges of the first side and second side is
rounded to enable tablets to roll more smoothly over the baffle.

Referring to Figure 2. the joining of the first and second sides (20) and (30)
creates an internal angle (40) no less than about 45°, no less than about 50°, no less
than about 55°, no less than about 50°, no less than about 65°, no less than about
70", no less than about 75°, no less than about 80°, or no less than about 85°. The
internal angle (40) formed by the first and second sides (20) and (30) is also no
greater than about 120°, no greater than about 115°, no greater than about 110°, no
greater than about 105°, no greater than about 100°, or no greater than about 95°. In
some embodiments, the internal angle is about 90°. in this context, the term "about"
means + 1°. Referring to Figure 1, in some embodiments, the length of the baffle
from first side tip (28) and/or second side tip (38) along top edges (22) and/or (32) is
at least about 6 inches, at least about 8 inches, at least about 10 inches, at least
about 12 inches, at least about 14 inches, at least about 16 inches, at least about 18
inches, a} least about 20 inches, at least about 24 inches, or longer. In some
embodiments, the length of the baffle from first side tip (28) and/or second side tip
(38) along fop edges (22) and/or (32) is selected such that the gap between the
convergence of the first side tip (28) and the second side tip (38) and the end of the
cylindrical surface (52) is as described below.
Also referring to Figure 2, the height of the baffle (10) ranges from about 1
inch to about 8 inches, or from about 5 inches to about 8 inches, or from about 7
inches to about 8 inches, or from about 2 inches to about 4 inches. As used herein,
the height of the baffle is the distance between the intersection of the lateral edge
(26) and the lateral edge (36), and a surface point. As used herein, a surface point
refers to a point on the surface which is midway between the point at which the
lateral edge (26) intersects the surface and the point at which the lateral edge (36)
intersects the surface, when the baffle is placed on the surface (for example, see
Figure 4). Referring to Figure 3, in some embodiments, the height of the baffle (10)
is about 3 inches. In some embodiments, the height of the baffle (10) is about 6.5
inches. In addition, baffle (10) comprises a length that is no less than about 1/16
inch, no less than about 1/2 inch, or no less than about 1 inch and no greater than
about 4 inches, no greater than about 3 inches, or no greater than about 2 inches
shorter than the width of the cylindrical surface (52) of the coating pan (50), thus
leaving a gap between the single tip of the baffle (10) and the edge of the cylindrical
surface (52) of the coating pan (50). In this context, the term "about" means ± % inch.

The sides (20) and (30) of baffle (10) can be perforated or ncn perforated but
are preferably non-peiforated, and can be made of any material suitable for coating
pharmaceutical formulations including, but not limited to, metals such as stainless
steel, plastic, fiberglass, polytetrafiuoroethylene (Teflon™), and the like In some
embodiments, the surfaces of the sides (20) and (30) are smooth.
The invention further provides a coating pan (50). Referring to Figure 3, the
coating pan (50) comprises a cylindrical surface (52) for receiving a pharmaceutical
formulation, an outer wall (54) in contact with one end of the cylindrical surface (52),
an inner wall (56) in contact with the other end of the cylindrical surface (52), and at
least one baffle (10) as described above. Referring to Figure 4, the lateral edges (26)
and (36) of the sides (20) and (30) of the baffle (10) contact the inner wall (56) or
outer wall (54) of the coating pan (50). The bottom edges (24) and (34) of the sides
(20) and (30) forming baffle (10) contact the cylindrical surface (52) of the coating
pan (50). The coating pan (50) can comprise at least one, at least two, at least three,
at least four, at least five, or at least six baffles (10). The baffles (10) can be fastened
to the coating pan (50) by any means known to the skilled artisan including, for
example, those means described above.
In some embodiments, the single tip of at least one baffle (10) formed by the
convergence of the first side tip (28) and the second side tip (38) does not extend the
entire width of the cylindrical surface (52). Referring to Figure 4, this leaves a gap
between the convergence of the first side tip (28) and the second side tip (38) and
the end of the cylindrical surface (52). In some embodiments, the tip of all baffles (10)
formed by the convergence of the first side tip (28) and the second side tip (38) does
not extend the entire width of the cylindrical surface (52).
In some embodiments, the gap between the convergence of the first side tip
(28) and the second side tip (38) and the end of the cylindrical surface (52) is a
distance that is from about 2% to about 50% of the length of the baffle from first side
tip (28) and/or second side tip (38) along top edges (22) and/or (32); or from about
2% to about 30% of such length, or from about 2% to about 20% of such length; or
from about 2% to about 15% of such length; or from about 10% to about 15% of such
length, or from about 12% to about 13% of such length, or from about 2% to about
10% of such length. !n some embodiments, the gap is about 12.5% of such length.

Where two or more baffles (10) are present within a coating pan (50). in some
embodiments, at least two of the baffles (10) are oriented in the opposite direction to
each other. Referring to Figure 3. the two baffles (10) are oriented such that the
lateral edges (26) and (36) of one baffle (10) is contacting the inner wail (56) of the
coating pan (50) while the lateral edges (26) and (36) of the other baffle (10) is
contacting the outer wall (54) of the coating pan (50). This orientation is also depicted
in Figure 4.
In some embodiments, as depicted in Figure 4, the flat side (20) of the baffle
(10) is aligned perpendicularly with the cylindrical surface (52) of the coating pan
(50). In other embodiments, the flat side (20) of the baffle (10) can be aligned at any
desired angle with the cylindrical surface (52) of the coating pan (50).
The invention also provides a coating apparatus (not shown) comprising a
coating pan (50) described above. Coating apparati are well known to the skilled
artisan and are commercially available. Suitable coating apparati include, but are not
limited to. a 24" Comp-U-Lab coaler (Thomas Engineering, Inc.. Hoffman Estates,
IL).
The invention further provides methods of manufacturing a baffle (10). For
example, a template of the baffle (10), such as a cardboard, wood or plastic
template, can be created using the contour of the coating pan (50). A baffle material,
such as any of the materials described above, can be cut and shaped according to
the template. In some embodiments, the shaping of the baffle (10) can be
accomplished using a lathe. The baffles (10) can be fastened by any means to the
coating pan (50). In some embodiments, the baffles (10) are screwed to the coating
pan (50) through pre-existing perforated bed holes.
The invention further provides methods of coating a pharmaceutical
formulation with a coating composition comprising introducing the pharmaceutical
formulation and coating composition into any coating pan (50) desribed herein and
rotating the coating pan (50). Preferably the coating composition comprises at least
one sugar.
In some embodiments, the plurality of pharmaceutical compositions produced
by the method of coating have a cracking rate of less than or equal to about 5%, less
than or equal to about 4%, or less than or equal to about 3%. In this context, a
plurality refers to one hundred or more pharmaceutical compositions. In this context.

the term "about" refers to plus or minus 0 5%. Cracking rate is measured by allowing
100 coated pharmaceutical formulations to slide down a plexiglass tube (one inch
I.D. X 36 inches at 37 deg. ± 2 deg.) into a 1 L stainless steel beaker (held at the
same angle). This step was repeated four additional times. Subsequently, the
coating is examined for the percent of crack.
Pharmaceutical formulations can be conveniently coated in accordance with
known procedures using commercially available coating apparati with the coating
pans (50) and baffles (10) described herein by employing standard methods and
procedures known to those skilled in the art. It will be appreciated that where typical
or preferred process conditions are given, other process conditions can also be used
unless otherwise stated. Optimum coating conditions may vary v/ith the particular
pharmaceutical composition and coating composition, but such conditions can be
determined by one skilled in the art by routine optimization procedures. Those skilled
in the art of pharmaceutical formulation coatings will recognize that the nature and
order of the steps presented may be varied for the purpose of optimizing the coating
of the pharmaceutical formulations. For example, a suitable reference for coating
pharmaceutical formulations is Introduction to the Coating of Pharmaceutical Oral,
Solid-dosage Forms, Stuart C. Porter. Pharmaceutical Unit Processes and Solid
Dosage Form Development: Industry and Regulatory Perspectives. May 28. 1997.
which is incorporated herein by reference in its entirety.
The baffles described herein can be used to coat various pharmaceutical
formulations such as those described in U.S. Provisional Application Ser. No.
No. 60/864,718, filed Nov. 7, 2006. which is incorporated herein by reference in its
entirety.
EXAMPLES
The following describes the coating of representative pharmaceutical
formulations of this invention in greater detail. The following examples are offered tor
illustrative purposes, and are not intended to lirnit the invention in any manner. Those
of skill in the art v^ill readily recognize a variety of noncritical parameters which can
be changed or modified to yield essentially the same results.
EX.AMPLE 1
COATING COMPOSITIONS

Exemplary Coating of Pharmaceutical Formulations Using Baffles Described Herein
Oval biconvex shaped hydrogel-based Premarin tablets with 0.412 inch x
0.225 inch x 0.034 inch dimension were used for the coating trials. The tablets
contain 0.375% of Conjugated Estrogens, 15% Microcrystalline cellulose (Avicel PH
101), 48.51% Lactose Monohydrate Spray Dried. 27.5% HPMC K100M CR, and
0 25% Magnesium Stearate and had an average weight of 120 mg with a related
standard deviation in the range of 0.5 to 1.4%. The hardness of tablet cores ranged
from 7 to 10 scu.
Several characteristics of the coated pharmaceutical formulation were
observed and monitored including, for example, the physical appearance, percentage
of cracked sugar coats, weight variation (at different weight gains), and content
uniformity of MPA of resulting tablets, it was found that tablets coated using baffles
designed for film coating or even those traditionally for sugar coating have
unacceptable weight variation as well as content uniformity. Different placement of
the baffles in the perforate coaling pan did not provide improved mixing efficiency.
Although a symmetrical V-shaped baffle design may have improved weight variation,
because of the nature of the manual sugar coating process, the percentage of
cracked sugar coats and broken tablets were far too high to pursue this option. A
baffle which is an embodiment of the present invention provided an improved mixing
environment since lower weight variations and content uniformity, and fewer
damaged tablets were observed. In addition, the physical appearance of the tablets
was more elegant. The edges of the tablets rounded faster when using the baffles
which are an embodiment of the present invention, and the application process was
simplified when compared with that used in other baffle designs. When the baffle
which is an embodiment of the present invention was scaled up to GCX-1000, it as
well demonstrated a superior mixing efficiency compared to the traditional sugar and
film coating baffles.

EXAMPLE 2
MANUFACTURING PROCESS
MPA Filler Suspensions Preparation
The MPA filler suspensions were prepared using following steps:
1) Add water, purified in an appropriately sized jacketed container; while
mixing with a high shear mixer, heat the water to 65°C±5°C and add the sucrose;
reheat to 65°C; mix until all the sucrose is dissolved.
2) Cool the above solution to 40-45°C; slowly add to the vortex using a high
shear mixer, the Polyethylene Glycol, Povidone K25, Microcrystalline Cellulose, and
Cab-0-Sil; mix above solution for another 1 minute using a high shear mixer.
3) While mixing with the high shear mixer, cool the above suspension to 35-
39°C and slowly add Sodium Lauryl Sulfate and MPA.
4) Mix continuously using a low shear mixer, while maintaining the tank
temperature at 35°C to 39°C during the entire application process.
MPA Filler Suspension Application When Using Comp-U-Lab Coater
1) To the 24" perforated coating pan with the different designed baffles, load
approximately 33,333 hydrogel Premarin tablet cores.
2) Set inlet temperature at 40°C and inlet airflow at 75 cfm; preheat the
tablets to about 30°C, dew point 11°C and exhaust temperature at 35 °C.
3) With the pan rotating at 18 rpm. apply incremental shots of MPA filler
suspension by a syringe until an average tablet weight gain of 106 mg is achieved;
each shot is followed by a tumbling jog cycle of 180-300 seconds (no air through the
coating pan) followed by a drying phase of 60-180 seconds.

MPA Filler Suspension Application When Scale-up to GCX-1000
1) To the GCX-1000 coater pan with the different designed baffles, load
approximately 166,666 hydrogel Premarin tablet cores.
2) Set inlet temperature at 35°C and inlet airflow at 250 cfm; preheat the
tablets to about 30°C, dew point 12°C and exhaust temperature at 30°C.
3) Mount two Graco guns at equal distance on the boom; install hydraulic
nozzles (Spraying Systems 11001-SS tips) onto the Graco guns; connect a Graco
pump (piston pump) to the suspension supply line; adjust the suspension spray
pressure at a pressure of 80-100 psi in order to produce a fan shape spray that
covers the entire tablet bed; with the pan rotating at 10 rpm, spray incremental shots
of MPA filler suspension until an average tablet weight gain of 106 mg is achieved;
each shot is followed by a tumbling jog cycle of 180-300 seconds (no air through the
coating pan) followed by a drying phase of 60-180 seconds.
Color Suspensions Preparation
1) Add Water, purified in an appropriately sized jacketed container; while
mixing with a high shear mixer, heat the vioter to 65°C±5°C and add the Sucrose;
reheat to 65°C: continue stirring until all the sucrose is dissolved.
2) Add the Povidone and Titanium Dioxide; mix using a high shear mixer to
insure homogeneous suspension.
3) Add Cab-O-Sil and mix using a high shear mixer to make a homogeneous
suspension.
4) Cool the suspension to 35-39'C.
5) Mix continuously using the low shear mixer, while maintaining the tank
temperature at 35°C to 39°C during the entire application process.
Color Suspension Application
1) To a 24" perforated coating pan installed in the Comp-U-Lab coater with
the special designed baffles, load approximately 33,333 Premarin/MPA filled tablets.
2) Set inlet temperature at 40°C and inlet airflow at 75 cfm; preheat the
tablets to about 30°C, dew point 11°C and exhaust temperature at 35 °C.

3) With the pan rotating at 18 rpm, apply incremental shots of color
suspension until an average tablet weight gain of 25 mg is achieved; each shot is
followed by a tumbling jog cycle of 180-300 seconds (no air through the coating pan)
followed by a drying phase of 60-180 seconds.
Preparation and Application of Polish
1) Prepare the polish suspension by suspending the Carnauba Wax, NF,
#120 in the Mineral Spirits, Odorless with vigorous stirring,
2) Apply the polish suspension to the rolling tablets; continue rolling until a
satisfactory gloss is obtained.



Baffle A is primarily used for film coating.
Baffle B is a sugar coating baffle. Since the Baffle B did not extend from the
front to the back of the pan, it was questionable whether there were dead zones at
the back of the pan during mixing.
A handmade extension of 6.5" v.'as attached to the Baffle B (Baffle C). This
leads the design of Baffle D.
The purpose of Baffle E was to evaluate whether the installation configuration
had any contributing influence on the uniformity of mixing.
Since Baffle A through E all generated non-symmetrical patterns of tablet
distribution in the pan, Baffle F was designed in an attempt to obtain a balanced
distribution of tablets in the back of the pan during mixing.
Baffle G (see Figures 1 and 2 herein) is an embodiment of the present
invention The edge (22/32) formed by the joining of the respective top edges of the
first side and second side is rounded to enable tablets to roll more smoothly over the
baffle.
This design prevented wetted tablets from sticking underneath the baffles during
coating as was observed with Baffles A-F. The installation configuration of Baffle G
(see Figures 3 and 4 herein) in the pan can also effectively prevent dead zones since
the baffles force tablets to travel from back to front and vice versa during mixing
Baffle H was designed to provide less resistance to the tablet flow and allow
the tablets to experience maximum contact with each other when passing through
the spaces between each spike. Another advantage of this unique design was that all
the spikes could be-re-configured for additional experiments. This would allow better
distribution of the coating material from tablet to tablet and consequently produce a
more uniform surface.
Baffle I was generated as an improvement of Baffle F. During the coating
using Baffle F, it was observed that there were tablets sticking behind the baffles. In

order to reduce the sticking, a perforated extension was installed at the back of each
baffle.
EXAMPLE 4
MIXING EFFICIENCY STUDY USING COMP-U-LAB 24
The mixing efficiency study was carried out by charging the pan with three
equal weights of different color tablets. Purple tablets were placed at the front
position of the pan, white tablets were placed at the center, and pink tablets were at
the back of (he coaling pan. Coating suspension was applied with the aid of a syringe
to the cascading tablet bed. After one tumbling jog and dry cycle, the pan was
stopped and 100 tablets were collected from front, center, and back positions of the
pan. The distribution of each color tablet at these three positions in the pan was
calculated by counting number of tablets of each color. The pan was restarted again,
and another shot of coating suspension was applied with a tumbling jog and dry
cycle. The distribution after the second shot application was calculated. This exercise
was repeated for one more shot application and the distribution was calculated
The mixing efficiency study was carried out using Baffles B, E, F, and G,
respectively. From the data showed in Tables 5, 6, 7 and 8 it can be seen that use of
Baffles B, F and G resulted in close to a uniform distribution even after the first shot.
However, in the case of Baffle E, the tablets are not uniformly mixed at the back of
the pan even after three shots. Thus, this type of baffle alignment does not provide
efficient mixing.

EXAMPLE 5
PHYSICAL APPEARANCE EVALUATION
The physical appearance of tablets was examined by observing the surface of
the tablets visually, or with magnifying glasses, for surface anomalies during the
coating run. In most cases, sugar coating is intended to improve the appearance of

the tablets. The quality of any subsequent color and polishing processes is highly
dependent upon the uniformity of the substrate filler coat. Thus, it is important to
ensure that filled tablets are not cracked or chipped.
The physical appearance and percentage of cracked tablets of the batches
5 manufactured with the different baffles was evaluated. The results are presented in
Table 9. Tablets coated using Baffle F resulted in a high percent of cracked tablets.
In addition, the appearance of the coated tablets is poor. On the other hand. Baffle G
produced tablets of elegant appearance and low percentage of cracked tablets.
During the coating process when using Baffle F, it was observed that the wetted
10 tablets fell onto the bottom of the coating pan from the "sheif-effect generated by the
baffles. The "shelf-effect" was caused by the shape and angle of the baffles to the
pan. The wetted tablets were held by the baffles and brought up to the top of the pan.
This "shelf-effect" produced an unusual amount of broken tablets. in addition, the
wetted tablets constantly stuck to the back of the baffles. In the case of Baffle G, the
15 wetted tablets rolled instead of falling onto the bottom of the pan. There were no
sticking issues during the entire coating process and this might have contributed to
the good appearance and strong coating (less cracking and broken tablets). Even
though Baffle H can provide tablets with a good appearance, there was a great
amount of sugar crystal build-up on the tips of baffles during the coating process. The
20 tablets coated using this baffle exhibit a high cracking percentage. With Baffle I, the
sticking issues observed with Baffle F were resolved. However, the tablets still fell
instead of rolled onto the bottom of the coating pan since the "shelf-effect" still
existed- Therefore, this baffle produces a high percentage of cracked and brittle
tablets.
25 Table 9
Physical Appearance, Cracking Rate, and Weight Variation of
Tablets Coated Using Different Baffles at 106 mg Targeted Weight Gain


EXAMPLE 6
TABLET CRACKING PERCENTAGE
Coaled tablets were allowed to slide down a tube into a stainless steel
beaker. This process was repeated four times. Subsequently, the sugar coatings
were examined for the percent of crack. The results are reported in Table 9 above.
EXAMPLE 7
WEIGHT VARIATION STUDY AT DIFFERENT COATING STAGES USING COMP-
U-LAB 24
Samples of approximately 100 tablets were taken at different weight gains
during the course of coating. Weight variation of 100 tablets was evaluated using
Mocon Automatic Balance Analysis tester (Modern Controls, Inc., Minneapolis, MN).
The weight variation testing was performed at 25%. 50%. 75%, and 100%
targeted weight gain levels when using Baffle A, C, D, and E. The weight variation of
the batch coated using Baffle B was only evaluated at 100% targeted weight gain
level.
Baffle A was not efficient in providing low weight variation of sugar coating. At
100% application, the weight variation coefficient of variation was close to 5%. Baffle
C. with the handmade extension, was even less efficient since it generated the
highest weight variations. Baffle D, which was made by increasing the length of
Baffle B. did not improve the mixing efficiency as there is no improvement in weight
variation when comparing the use of Baffle B or D at 100% weight gain.
In the case of Baffle E, one of the baffles was installed from back to front of
the pan in the same directions as the other two baffles. This alignment provided a
different pattern of tablet movement in the pan. It was observed that the tablets had a
tendency to stay at the back of the pan at most of the times during coating. As
indicated in Figure 5, the weight variation from this experiment was not significantly
different from the experiment with Baffle B. Therefore, this design could not provide
an advantage for improving the mixing uniformity. It appears that wetted tablets have
to travel from the back to front and vice versa in the coating pan in order to produce a
uniform mixing thus providing the lowest possible RSD for weight variation

The results of studies on Baffles F, G, H and I are displayed in Figure 6. it is
evident that Baffle F provides the lowest of most consistent weight variation among
these four types of designs. Baffle G is belter than both Baffle H and Baffle I in
providing an acceptable weight variation. The perforated extensions of Baffle F, used
to produce Baffle I, did not provide any advantages in the respects to weight
variation.
EXAMPLE 8
CONTENT UNIFORMITY EVALUATION
Content unifornnity of MPA was measured upon completion of the coating
processes in the 24" coater. Figure 7 displays the results. The results concluded that
Baffles G and F produced tablets with better content uniformity for MPA as compared
to the others. Baffle F, however, would not produce an elegant tablet as
demonstrated with Baffle G.
EXAMPLE 9
EDGE ROUNDING RATE COMPARISON
The edge rounding rale is another important factor in the sugar coating
process since it may determine the length of the coating process, outcome of f;nal
batch appearance, percentage of cracked tablets and dissolution variability. Because
of the characteristics of sugar coating, the surface of the tablets is easier to cover
with the coating solution/suspension than the edges. The longer it takes to round off
the tablet edges, the longer the sugar coating process will be. There are several
factors influencing the edge rounding rate, however, the pan mixing mechanism,
which determines how the tablets move, is one of the most important factors. The
edge rounding rate obtained with certain baffle was investigated by taking pictures of
a tablet coated at 30% weight gain level. The presence of a rounded tablet edge at
this weight gain level signifies a rapid rounding rata and efficient mixing.
When Baffles F, G and H were used for coating tablets at 30% targeted
weight gain level (32 mg), the edges of the tablets coated using Baffle G were
rounded while those produced using Baffle F and Baffle H batches still required more
processing time. Thus, the edge rounding rate achieved with Baffle G was faster than
that with Baffles F and H, because Baffle G design can provide more efficient mixing.

EXAMPLE 10
SCALE-UP TO GCX-1000
The filler coat process was scaled-up to GCX-1000 batch size. Different baffle
designs, which included regular film coating and sugar coating baffles as well as
scaled-up Baffle G, were evaluated. Tablet weight variation at different coating
stages was measured using the same evaluation methodology in Comp-U-leb 24"
scale. In addition, content uniformity of MPA was determined. Figure 8 shows the
tablet weight variation at different coating stages and Figure 9 displays the results for
MPA content uniformity. These results confirm the more efficient mixing of Baffle G in
a larger scale.
When evaluating from all aspects for sugar coating in the current study, Baffle
G which is an embodiment of the present invention provided tablets with excellent
appearance, faster edge rounding rale, lower cracking rate, and lower weight
variation as well as content uniformity. Baffle G demonstrated good mixing
capabilities so that dead spots vvere effectively avoided at current studies at small as
well as large scale.
It is intended that each of the patents, applications, and printed publications
including books mentioned in this patent document be hereby incorporated by
reference in their entirety.
This application claims the benefit of priority of U.S. Provisional Appl. Ser. No.
60/864,726, filed Nov. 7, 2006, which is hereby incorporaled by reference in its
entirely.
As those skilled in the art will appreciate, numerous changes and
modifications may be made to the preferred embodiments of the invention without
departing from the spirit of the invention It is intended that all such variations fall
within the scope of the invention.

What is claimed is:
1. A baffle (10) comprising:
a first side (20) comprising a top edge (22), a bottom edge (24), and a lateral
edge (26), wherein said first side is flat, and wherein said top edge and said bottom
edge converge to form a first side tip (28)distal to said lateral edge; and
a second side (30)comprising a top edge (32), a bottom edge (34), and a
lateral edge (36), wherein said second side is curved, and wherein said top edge and
said bottom edge converge to form a second side tip (38)distal to said lateral edge;
wherein said first side and said second side are joined at each of said top
edges, and wherein joining of said first and second sides forms an internal angle of
no less than about 45° to no greater than about 120°, and wherein said first side tip
and said second side tip converge to form a single tip.
2. The baffle of claim 1, wherein said internal angle is no less than about
60° and no greater than about 105°.
3. The baffle of claim 1, wherein said internal angle is no less than about
75° and no greater than about 100°.
4. The baffle of claim 1, wherein said internal angle is about 90°.
5. The baffle of any one of claims 1 to 4, wherein said first side and
second side are joined seamlessly at said top edges.
6. The baffle of any one of claims 1 to 5, wherein the baffle material is
polytetrafluoroethylene.
7. The baffle of any one of claims 1 to 6, wherein the second side of the
baffle is curved in a convex manner from the lateral edge to the second side tip.
8. A baffle substatntially as shown in any of Figures 1, 2, 3, 4 or 16.
9- A coating pan comprising:

a cylindrical surface for receiving a pharmaceutical formulation;
an outer wall in contact with one end of said cylindrical surface;
an inner wall in contact with the other end of said cylindrical surface, and
at least one baffle of any of claims 1 to 8, wherein said lateral edges of said
sides forming said baffle contact said inner or outer wall of said coating pan, and said
bottom edges of said sides forming said baffle contact said cylindrical surface of said
coating pan.
10. The coating pan of claim 9, comprising a plurality of baffles according
to any of claims 1 to 8.
11. The coating pan of claim 10, comprising four or more baffles.
12. The coating pan of claim 10 or 11, wherein at least two of said baffles
are oriented in the opposite direction to each other such that the lateral edges of the
first side and second side respectively of one baffle are contacting the inner wall of
the coating pan while the lateral edges of the first side and second side respectively
of the other baffle are contacting the outer wall of the coating pan.
13. The coating pan of any one of claims 9 to 12, wherein the single tip of
said at least one baffle does not extend the entire width of the cylindrical surface of
the coating pan such that there is a gap between the single tip of the baffle and the
end of the cylindrical surface.
14. The coating pan of claim 13, wherein the gap is a distance which is
from about 2% to about 50% of the length of the baffle from the single tip along the
top edges.
15. The coating pan of any one of claims 9 to 14, wherein the fiat first side
of the one or more baffles is aligned perpendicularly with the cylindrical surface of the
coating pan.

16. A coating apparatus comprising a coating pan of any one of claims 9
to 15.
17. A method of coating a pharmaceutical formulation comprising
introducing said pharmaceutical formulation and a coating composition into a coating
pan of any of one of claims 9 to 15 and rotating said coating pan.
18. The method of claim 17, wherein the coating composition comprises
at feast one sugar.

This invention provides baffles
(10) for use in coating pans (50) within coating
apparatus, and methods of manufacturing the baf-
fles (10). The invention further provides methods
of coating pharmaceutical formulations using the
baffles (10) and coating pans (50) of the present
invention.