Tablet coating introduction, formulation, equipments, types and defects as per PCI syllabus.

1. TABLET COATING

2. INTRODUCTION
COATING COMPOSITION
FORMULATION OF COATING
DEFECTS IN COATING
CONTENTS 01
02
03
04
06
05
TYPES OF COATING
EQUIPMENTS AND METHODS
EMPLOYED IN COATING

3. INTRODUCTION

4. Tablet coating is the process where coating material is
applied to the surface of the tablet to achieve the
desired properties of dosage form over the uncoated
variety.
“

5. “
 Prevent from Light degradation/ photolytic
 Prevent from moisture degradation
 Masking off bitter taste
 Ease of swallowing
 Ease of distinguish in different batch production under one roof
 Gloss and attractive appeal for better marketing
 Ease of pharmacist in recognizing different colour coated tablets
 Additional mechanical strength to tablets
 Cross-contamination by dusting
 Enteric/ controlled release properties of tablets

6. The principles of tablet coating are relatively simple. The application of coating to
tablets, which is an additional step in the manufacturing process, increases the cost of
the product; therefore, the decision to coat a tablet is usually based on one or more of
the following objectives:
To mask the taste, odor, or color of the drug.
To provide physical and chemical protection for the drug.
To control the release of the drug from the tablet.
To protect the drug from the gastric environment of the stomach with an acid-
resistant enteric coating.
To incorporate another drug or formula adjuvant in the coating to avoid chemical
incompatibilities or to provide sequential drug release.
To improve the pharmaceutical elegance by use of special colors and contrasting
printing.
“

7. TYPES OF COATING

8. “ TYPES OF COATING
Controlled
release Coating
Enteric Coating
Dip Coating
Electrostatic Coating
Vacuum film Coating
Film Coating Press Coating
Sugar Coating Functional Coatings
Other Coatings
available

9. “ FILM COATING
• Film coating have a thickness of about 20-100 micrometer.
• It is the modern day more acceptable and advantageous
method.
Principle : in film coating we spray a thin film of polymer
around the tablet core .
Equipment used : conventional pan coaters
Advantage: Drying of solvent due to air inlet flow helps to
maintain a thin fil around the core.

10. Formulation used in film coating:
Polymer:
• The polymer should good solubility in fluids to facilitate dissolution of drug ( except
in case of modified release).
• It should have less viscosity for ease of spraying.
• Low permeability to prevent degradation and establish long shelf life.
• Strong mechanical strength to prevent form breaking during processing or
packaging.
Example: Cellulose derivatives
( HPMC) or Methacrylate amino ester copolymers
Plasticizers:
• They are used to increase the strength of polymeric film.
• They goes they provide mechanical support and prevent untangle-ness of
polymeric strands.
Examples: polyethylene glycol 400
diethyl phthalate
fractionated coconut oil

11. Colorants:
• They offer various advantages like –
• Prevent photolytic degradation
• Batter opacity
• Decrease the permeability of vapours through film
Examples : Iron oxide
titanium dioxide
aluminium lakes
Opaquant- extenders : They are used in formulation to give more pastel
colours and enhance film coverage. Examples: aluminium silicates,
magnesium carbonate, calcium sulphate…
Solvents :
• they are used to provide medium to polymers .
• They should be water soluble.
• Organic solvents should be avoided because-
 They can be toxic
 They can cause environmental degradation
 Polymer may be insoluble in them
 costly

12. Equipment used:
• Accetacota
• Hicoater
• Driacoater
• HTF/150
• IDA
Process requirements:
• Applicable atomizing sprayer
• Proper mixing of tablets
• Sufficient inflow of drying air to facilitate latent heat of evaporation
• Dust separator
Ideal characters of film coating:
• Even cover over all the tablets
• No abrasive edges
• Clear logo/break lines (not filled)
Coating faults:
 processing- not adequate dry air flow
 Formulation- film cracking around logo
Not film coated
Film coated

13. “SUGAR COATING
 Traditional method of coating
 In this method sucrose based solution / syrup is sprayed on the tablets.
Equipment used: conventional panning coaters
Ideal characters :
• even color all over the tablets
• Smooth spherical appearance
• Glossy look/ appeal
• Clear logo
Coating fault:
 process- splitting of coat due to uneven drying during coating

14. “SUGAR COATING STAGES
1.SEALING / WET PROOFING
2.SUBCOATING
3.SMOOTHING
4.COLOURING
5.POLISHING
6.PRINTING

15. WET PROOFING/ SEALING
It is done to provide a moisture barrier to the tablet core.
This gives physical and chemical stability to finished products
Water insoluble polymers like shellac, cellulose acid phthalate, ethyl cellulose,
polyvinyl acetate phthalate or HPMC are used.
Place the tablets in pan
Rotate at the speed of 10rpm ( air -30 degree Celsius )
Generally use 3 application of polymers
(ex: zein solution- 800ml/application)
Time period : 15-20 min.
*Apply talc if tablets stick to the pan.

16. SMOOTHING
It is done to provide a moisture barrier to the tablet core.
This gives physical and chemical stability to finished products
Water insoluble polymers like shellac, cellulose acid phthalate, ethyl cellulose,
polyvinyl acetate phthalate or HPMC are used.
Place the tablets in pan
Rotate at the speed of 10rpm ( air -30 degree Celsius )
Generally use 3 application of polymers
(ex: zein solution- 800ml/application)
Time period : 15-20 min.
*Apply talc if tablets stick to the pan.

17. SUB COATING
It is done to smooth up and remove roughness of tablet.
Several coats of simple syrup solution(60-70%) containing starch, gelatin or acacia is
applied.
Turn off the exhaust
Temp: 45-48 degree Celsius + speed: 12 rpm
Apply 5-15 coats with quick drying
Turn off after required smoothness
*Apply talc if tablets stick to the pan.

18. COLOURING
It is done to give color to tablets.
It is useful to distinguish tablets and provide appealing look.
Water soluble dyes or water insoluble pigments are used.
Clear the pan of any ingredient
Temp: 45-48 degree Celsius + speed: 12 rpm
Apply 3-4 coats with quick drying
After achieved color turn off the exhaust
*Apply talc if tablets stick to the pan

19. POLISHING
It is done to give glossy look to the tablet .
It is useful for patient compliance and marketing purpose.
Wax is dissolved in warm naphthalene solution or petroleum benzene solution and sprayed
on the tablets.
PRINTING
Logo is printed on the tablets using mechanical devices
driven by computerized drive.
QUALICAPSEUROPE
QI-300printing machine

20. PRESS COATING
“
Press coating involves the compaction of granular material around an already
preformed core using compressing equipment similar to that used for the core itself,
e.g. Manesty Drycota.
It is possible to apply two press coatings to a tablet core using suitable equipment, e.g.
Manesty Bicota.This equipment produces press-coated tablets with perfect separation
between active core and coating, as the two can be separated by an inert middle layer.
Disadvantage: Large or irregularly sized agglomerates of granules will cause the core
to tilt in the second die used for compression of the coating. Thus there is the
possibility of an incomplete coating, with the core being visible at the tablet surface.
Relative complexities of the mechanism used in the compressing equipment.

21. “ FUNCTIONAL COATINGS
They are used to provide pharmaceutical stability to tables and sustained release.
CONTROLLED RELEASE ENTERIC COATING
-uses multiarticulate system
-pellets/beads/granules
-coated via film coating
-compressed into capsules
Extruded
OR
Spheronized
granulates
Non - pareil
These are produced in modified
granulating equipment, with the
drug granulation extruded
through a mesh or other device
under pressure to form small
granulates which are
subsequently Spheronized.
These are sucrose
spheres which are
coated with the drug
plus an adhesive yet
water-soluble
polymer
This technique is used to protect
the tablet core from disintegration
in the acid environment of the
stomach for one or more of the
following reasons:
1. Prevention of acid attack on
active constituents unstable at low
pH.
2. To protect the stomach from the
irritant effect of certain drugs.
3. To facilitate absorption of a drug
that is preferentially absorbed
distal to the stomach.

23. “OTHER COATINGS
Dip coating Electrostatic
coating
Vacuum filled
coating
This type of coating is applied
by dipping core tablets m
coating Liquid and then dried.
But this process is not reliable
due to lack of speed.
In this type of coating, a substate
is present at which strong
electrostatic charge is applied
while coating material containing
opposite charge is sprayed over it
to get uniform coating.
This is new coating procedure- It
consist of a pan which hot water
jacketed. The tablets are place in
pan and vacuum is obtained by
sealing. air from pan is removed by
using nitrogen- The coating
solution is then applied by hydraulic
spray system Due to heated pan
evaporation takes place. The
vapours are removed by vacuum.

24. COATING
COMPOSITION AND
FORMULATION

25. “ COATING COMPOSITIONS
The coating materials may be a physical deposition of the material on the tablet substrate, or they may
form a continuous film with a wide variety of properties depending upon the composition of the coating
formulations. Coating materials are synthetic polymers, solvents, plasticizers, colorants, opaquant-
extenders, and miscellaneous coating solution components.
An ideal film coating material should have the following attributes:
 Solubility in solvent of choice for coating preparation.
 Solubility required for the intended use, e.g. free water-solubility, slow water-solubility, or pH-
dependent solubility (enteric coating) Capacity to produce an elegant looking product.
 Stability in the presence of heat, light, moisture, air, and the substrate being coated.
 The film properties should not change with aging.
 Essentially no color, taste or odor.
 Compatibility with common coating solution additives.
 Nontoxicity with no pharmacologic activity, and ease of application to the particles or tablets.
 Resistance to cracking, and provision of adequate moisture, light, odor, or drug sublimation barrier
when desired.
 No-bridging or filling of the debossed tablet surfaces by the film former.
Ease of printing procedure on high speed equipment.

26. “ • Non enteric materials
• Enteric materials
FILM FORMERS
1
2
3
4
5
6
SOLVENTS
COLOURANTS
OPAQUANT-EXTENDERS
MISCELLANEOUS COATING
SOLUTION COMPONENTS
PLASTICIZERS
FORMULATION OF COATING COMPOSITION

27. “ FILM FORMERS
1.Non enteric materials
Hydroxypropyl Methylcellulose
The polymer is prepared by reacting alkali-treated cellulose first with methyl chloride to introduce methoxy
groups and then with propylene oxide to introduce propylene glycol ether groups. The resulting products
are commercially available in different viscosity grades. This polymer is a material of choice for air
suspension and pan-spray coating systems. The reasons for its widespread acceptance include
(1) solubility characteristics of the polymer in gastrointestinal fluid, and in organic and aqueous solvent
systems
(2) , (2) noninterference with tablet disintegration and drug availability,
(3) (3) flexibility, chip resistance, and absence of taste or odor,
(4) (4) stability in the presence of heat, light, air, or reasonable levels of moisture and
(5) (5) ability to incorporate color and other additives into the film without difficulty.
(6) The interaction of this polymer with colorants is rare.
Hydroxypropyl methylcellulose closely approaches the desired attributes of an ideal polymer for film
coating. When used alone, the polymer has the tendency to bridge or fill the debossed tablet surfaces. A
mixture of hydroxypropyl methylcellulose with other polymers or plasticizers is used to eliminate bridging or
filling problems. This polymer is also used considerably in glossing solutions.

28. Methyl Hydroxy ethyl cellulose
 This polymer is prepared by reacting alkali-treated cellulose first with methyl chloride and then with ethylene oxide.
 A wide variety of viscosity grades are available.
 Because of its structural similarity to hydroxypropyl methylcellulose, this polymer is expected to have similar properties.
Hydroxypropyl cellulose
 This material is manufactured by treatment of cellulose with sodium hydroxide, followed by a reaction with propylene oxide
at an elevated temperature and pressure.
 It is soluble in water below 40°C (insoluble above 45°C), gastrointestinal fluids and many polar organic solvents.
 This polymer is extremely tacky as it dries from a solution system and may be desirable for a subcoat, but not for a color or
gloss coat.
 The polymer yields very flexible films. It is usually not used alone, but it is used in combination with other polymers to
improve the film characteristics.
Povidone
 Povidone is a synthetic polymer consisting of linear l-vinyl-2-pyrrolidinone groups.
 Povidone is usually available in four viscosity grades identified by their K values, which approximate K-15, K-30, K-60, and K-
90.
 The most common uses of povidone in pharmaceuticals (frequently K-30) are as a tablet binder and a tablet coating
 It has excellent solubility in a wide variety of organic solvents, in water, and in gastric and intestinal fluids.
 When dry, povidone films are clear, glossy, and hard.
 Povidone has been used to improve the dispersion of colorants in coating solutions to obtain a more uniformly colored film.

29. Polyethylene glycols
 Polyethylene glycols (PEG) are manufactured by the reaction of ethylene glycol with ethylene oxide in the presence
of sodium hydroxide at elevated temperature and under pressure.
 The materials with low molecular weights (200 to 600 series) are liquid at room temperature and are used as
plasticizers for coating solution films. The materials with high molecular weights (series 900 to 8,000) are white,
waxy solids at room temperature.
 These polymers are used in combination with other polymers to modify film properties. Combinations of
polyethylene glycol waxes with cellulose acetate phthalate provide films that are soluble in gastric fluids.
 Such systems constituted one of the first commercially used nonenteric film coating processes.
Acrylate Polymers
 A series of acrylate polymers is marketed under the trademark Eudragit. Eudragit E is a cationic copolymer based on
dimethyl-aminoethyl methacrylate and other neutral methacrylic acid esters, and is the only Eudragit material that
is freely soluble in gastric fluid up to pH 5, and expandable and permeable above pH 5.
 This material is available as
(1) organic solution (12.5%) in isopropanol/acetone,
(2) solid material, or
(3) 30% aqueous dispersion.
 These are available only as organic solutions and solid materials. These polymers produce films for the delayed-
action (pHindependent) preparations similar to ethylcellulose formulations.
Others
 Ethyl cellulose
 Sodium Carboxymethylcellulose

30. 2.Enteric Materials
Some of the most important reasons for enteric coating are as follows:
1. To protect acid-labile drugs from the gastric fluid, e.g. enzymes and certain antibiotics.
2. To prevent gastric distress or nausea due to irritation from a drug, e.g. sodium salicylate.
3. To deliver drugs intended for local action in the intestines, e.g. intestinal antiseptics could be delivered to
their site of action in a concentrated form and bypass systemic absorption in the stomach.
4. To deliver drugs that are optimally absorbed in the small intestine to their primary absorption site in their
most concentrated form.
5. To provide a delayed-release component for repeat-action tablets.
An ideal enteric coating material should have the following properties:
 Resistance to gastric fluids.
 Ready susceptibility to or permeability to intestinal fluids.
 Compatibility with most coating solution components and the drug substrates.
 Stability alone and in coating solutions. The films should not change on aging.
 Formation of a continuous (uninterrupted) film.
 Non toxicity.
 Low cost.
 Ease of application without specialized equipment.
 Ability to be readily printed or to allow film to be applied to debossed tablets

31. Cellulose Acetate Phthalate
 Cellulose acetate phthalate (CAP) has been widely used in the industry. It has the disadvantage of dissolving only
above pH 6, and possibly delaying the absorption of drugs.
 It is also hygroscopic and relatively permeable to moisture and gastric fluids, in comparison with some other enteric
polymers.
 CAP films are susceptible to hydrolytic removal of phthalic and acetic acids, resulting in a change of film properties.
 CAP films are brittle and usually formulated with hydrophobic-film forming materials or adjuvants to achieve a better
enteric film.
Acrylate Polymers
 Two forms of commercially available enteric acrylic resins are Eudragit L and Eudragit S. Both resins produce films
that are resistant to gastric fluid. Eudragit L and S are soluble in intestinal fluid at pH 6 and 7, respectively. Eudragit L
is available as an organic solution (Isopropanol), solid, or aqueous dispersion.
 Eudragit S is available only as an organic solution (Isopropanol) and solid.
Polyvinyl Acetate Phthalate
 Polyvinyl acetate phthalate (PVAP) is manufactured by the esterification of a partially hydrolyzed polyvinyl acetate
with phthalic anhydride.
 It is supplied as ready-to-use or ready-to-disperse enteric systems.
Hydroxypropyl Methylcellulose Phthalate
 These are derived from hydroxypropyl methyl-cellulose, by esterification with phthalic anhydride.
 HPMCP is the trade name for hydroxypropyl methylcellulose phthalate.
 These polymers dissolve at a lower pH (at 5 to 5.5) than CAP or acrylic copolymers, and this solubility characteristic
may result in higher bioavailability of some specific drugs.
 These polymers are quite stable because of their absence of labile acetyl groups

32. Solvents
The primary function of a solvent system is to dissolve or disperse the polymers and other additives and
convey them to the substrate surface. All major manufacturers of polymers for tablet coating provide basic
physical chemical data on their polymers. These data are usually helpful to a formulator.
Some important considerations for an ideal solvent system are as follows:
 It should either dissolve or disperse the polymer system.
 It should easily disperse other coating solution components into the solvent system.
 Small concentrations of polymers (2 to 10%) should not result in an extremely viscous solution
system (>300 cps), creating processing problems.
 It should be colorless, tasteless, odorless, inexpensive, nontoxic, inert, and nonflammable.
 It should have a rapid drying rate (the ability to coat a 300 kg load in 3 to 5 hours).
 It should have no environmental impact.
 The most widely used solvents, either alone or in combination are water, ethanol methanol, isopropanol,
chloroform, acetone, methy-lethylketone, and methylene chloride. Because of environmental and
economic considerations, water is the solvent of choice; however, several polymers cannot be applied from
aqueous systems.
 Drugs that readily hydrolyze in the presence of water can be more effectively coated with non-aqueous-
solvent-based coatings. Such a process might require applying an initial sealing coat from an organic based
sub coating, followed by aqueous color and gloss coating. The use of organic-solvent-based film coatings
will undoubtedly decrease as better aqueous systems are developed.
“

33.  Polyhydric alcohols, such as propylene glycol or polyethylene glycol (PEG) or glycerol
 Acetate esters, such as triacetin (glycerol triacetate) or triethyl citrate(TEC)
 Glycerides, such as acetylated monoglycerides
 Oils, such as mineral oil or vegetable oils
Colorants and pigments : that increase opacity, light protection and provide coloration:
 Water insoluble lakes: Such as indigo carmine, tartrazine, allura red, and quinoline yellow (water soluble dyes of these
same colors may also be used)
 Inorganic pigments: Titanium dioxide, iron oxides, and pearlescent pigments (containing mica)
 Natural colorants: including vegetable juice, carotenoids, and turmeric
Glidants :which are incorporated to produce coatings which are smooth and tack free
 talc
 waxes, such as carnauba wax
 Stearates
Flavouringagents : It may be used to improve the patient experience or provide brand value
 Sweeteners, which may be natural or high intensity artificial (such as sucralose)
 natural or artificial flavors, such as mint, vanilla, or berry
Viscosity modifier :which often allow coatings to be applied in a more efficient process or create an
improved tablet appearance
 Carbohydrates, such as lactose, polydextrose, or starch
 Gums, such as acacia or xanthan gum
Plasticizing agent :This will reduce the film – forming temperature of the polymer and make it possible to
apply at lower temperatures, and improve the elasticity of the coating film:

34. COATING EQUIPMENTS

35. “COATING EQUIPMENTS
CONVENTIONAL
PAN COATER
PERFORATED PAN
COATER
FLUIDIZED BED
COATER
Immersion tube
Baffled pan and diffuser
Immersion sword system
Accela-cota system
Dria-cota system
Hi-coater system

36. “ CONVENTIONAL PAN COATERS
• Standard coating pan, which is also known as the
conventional pan system.
• It consists of a circular pan made of metal mounted on a
stand.
• The pan is rotated by a motor. It is 8-60 inches or 15 to 200
cm in diameter.
• The pan is slightly tilted to an angle of about 450 degree to
the bench top. There is provision of supply of hot air through
inlet port. The heated air is directed into the tablet bed and
air leaves by means of ducts.
• The temperature of hot air should be maintained. Because
very high temperature may decompose or degrade essential
chemical constituents of the tablets.
• The coating solutions are sprayed on the rotating tablets.
The spraying system distribute the coating solution more
evenly and reduce the drying time.

37. • This type of tablet coating machine is popular because it is easy to operate and drug can be easily
removed due to wide mouth of pan. But the pan also have disadvantages such as improper mixing,
not suitable if volatile solvents are used and Improper balance of inlet and exhaust air.
Immersion Tube System:
It consist of long tube which is immersed in the tablet bed. This tube has a spray nozzle at its tip
that delivers both the hot air and coating solution simultaneously. The heated air flows upwards
and leaves the system by conventional due This enhance the drying efficiency.

38. Baffled Pan and Diffuser
A baffled pan and diffuser, which is
also called the Pellegrini. In this
process, the tablet coater can
distribute drying air uniformly on the
coated tablets. They also improves
the drying efficiency of standard
coating pan.
Immersion Sword System:
It consist of a perforated metal
sword which is immersed in the
tablet bed, During the drying
process, the drying air flows
through perforated metal sword
then upwards through the bed.

39. PERFORATED PAN COATER
It consists of either a full or partial perforated drum that rotates on a horizontal axis in a
closed chamber. The coating drum is an enclosed housing with various spray nozzles that
atomize the coating solution. Drying air is passed through the tablets and is exhausted
through perforations in the drum. Perforated pan coaters are highly efficient due to high
coating capacity. They are available as:
It consist of Baffles, spray gun and
Dry air inlet. Baffles ensure the
freely mixing of tablets within the
drum during its rotation. Spray
gun atomizes coating solution on
to the tablets. Dry inlet air flows
in between the tablets and leaves
the drum through the
perforations. This process is fast
and drying efficiency is also good.
Accela-cota system:

40. Dria-cota system :
It consist of hollow perforated ribs situated
on the inside periphery tablet coating drum.
When drum rotates, the spray nozzle
atomizes coating solution to the tablets
from the top section. The drying air enters
into the drum from below the tablets and
exit through the back of the pan.
Hi-coater:
The drying air is passed through tablet bed and then
exhausted through the perforations below the coating
drum. This decrease the coating time.
Glatt Coater:
The drying air passes through the tablet bed and leaves
via exhaust duct. Its unique design lessen turbulence
around the spray nozzle and provide even distribution of
the coating solution on the tablets. The baffles on
periphery ensures an effective mixing of tablets.

41. Glatt Coater

42. FLUIDIZED BED COATER (AIR SUSPENSION)
It is also highly efficient coating system. It consist of a vertical cylinder. The drying air flows all the
tablets in fluidized manner. The air stream enters the column causing the tablets to rise in the center,
then they fall toward the chamber walls and move downward to re-enter the air stream at the bottom
of the chamber. Spray nozzle, located on the top or bottom of the chamber, introduces the coating
fluid into a fluidized bed.

43. Spray rate
The spray rate affect the quality and uniformity of the film. A low coating liquid spray rate
causes incomplete coalescence of polymer due to insufficient wetting. A high coating liquid
spray rate may result in over wetting of the tablet surface. If the spray rate is high and the
tablet surface temperature is low, it will produces cracks in the films.
Atomizing air pressure
If spraying air pressure is excessive, it will cause inadequate droplet spreading and
coalescence. If there is low spraying air pressure then the tablets get stick to each other.
Inlet air temperature
The inlet air temperature affects the drying efficiency. High inlet air temperature increases
the drying efficiency of the aqueous film coating process. Too much air temperature
decreases the coating efficiency.
Rotating speed of pan
The pan speed affects the time the tablets spend on the spraying zone. Too much rotating
speed of the pan cause attrition an&breakage of tablet.
“PROCESS PARAMETER

44. DEFECTS IN COATING

45. “Defects in Coating
Variations in formulation and processing conditions may result in
unacceptable quality defects in the film coating. The source of these
defects and some of their probable causes are described in the
following sections.

46. Remedies
“Blistering
Introduction
Causes
It is local
detachment of
film from the
substrate forming
blister.
Entrapment of gases in or
underneath the film due
to overheating either
during spraying or at the
end of the coating run
Effect of temperature on
the strength, elasticity
and adhesion of the film.
Use mild drying
condition

47. “ Remedies
Introduction
Causes
Cratering
It is defect of film
coating whereby
volcanic-like
craters appears
exposing the
tablet surface.
The coating solution penetrates
the surface of the tablet, often
at the crown where the surface
is more porous, causing
localized disintegration of the
core and disruption of the
coating
Inefficient drying
. • Higher rate of application of
coating solution.
• Use efficient and
optimum drying
conditions.
• Increase viscosity of
coating solution to
decrease spray
application rate.

48. “ Remedies
Introduction
Causes
• It is defect where
isolated areas of film
are pulled away from
the surface when the
tablet sticks together
and then part.
Conditions similar to cratering
that produces an overly wet
tablet bed where adjacent
tablets can stick together and
then break apart.
Inefficient drying. • Higher
rate of application of coating
solution.
Use optimum and
efficient drying
conditions or
increase the inlet
air temperature. •
Decrease the rater
of application of
coating solution by
increasing viscosity
of coating solution.
Picking

49. “ Remedies
Introduction
Causes
• It is defect whereby
pits occur in the
surface of a tablet
core without any
visible disruption of
the film coating.
Temperature of the tablet
core is greater than the
melting point of the
materials used in the tablet
formulation
Inappropriate drying (inlet
air) temperature.
Dispensing with
preheating procedures at
the initiation of coating
and modifying the drying
(inlet air) temperature
such that the
temperature of the
tablet core is not greater
than the melting point of
the batch of additives
used.
Pitting

50. “ Remedies
Introduction
Causes
It is defect where
coating becomes
dull immediately or
after prolonged
storage at high
temperatures.
It is due to collection on the
surface of low molecular weight
ingredients included in the
coating formulation. In most
circumstances the ingredient
will be plasticizer.
High concentration and low
molecular weight of plasticizer
Decrease
plasticizer
concentration and
increase molecular
weight of
plasticizer
Blooming

51. “ Remedies
Introduction
Causes
Blushing
It is defect best
described as
whitish specks or
haziness in the
film.
.
• Decrease the drying air
temperature
• Avoid use of sorbitol
with Hydroxy Propyl
Cellulose, Hydroxy Propyl
Methyl Cellulose, Methyl
Cellulose and Cellulose
ethers
It is thought to be due to precipitated
polymer exacerbated by the use of
high coating temperature at or above
the thermal gelation temperature of
the polymers
High coating temperature. • Use of
sorbitol in formulation which causes
largest fall in the thermal gelation
temperature of the Hydroxy Propyl
Cellulose, Hydroxy Propyl Methyl
Cellulose, Methyl Cellulose and
Cellulose ethers

52. “ Remedies
Introduction
Causes
Cracking/Splitting
It is defect in which the
film either cracks across
the crown of the tablet
(cracking) or splits
around the edges of the
tablet (Splitting).
Internal stress in the film
exceeds tensile strength
of the film.
Use of higher molecular
weight polymers or
polymeric blends
Use lower molecular
weight polymers or
polymeric blends.
Also adjust
plasticizer type and
concentration.

53. “ Remedies
Introduction
Causes
Orange Peel/Roughness
It is surface defect
resulting in the film
being rough and
non-glossy.
Appearance is
similar to that of an
orange.
Inadequate spreading
of the coating
solution before
drying.
Rapid Drying. •
High solution
viscosity
• Use mild drying
conditions.
• Use additional
solvents to decrease
viscosity of solution.

54. “Some other defects
Colour variation Bridging and
Filling
Twinning
This is caused by processing
conditions or the
formulation. Improper
mixing, uneven spray
pattern, and insufficient
coating may result in color
variation. The migration of
soluble dyes, plasticizers, and
other additives during drying
may give the coating a
mottled or spotted
appearance
. The use of lake dyes
eliminates dye migration.
This occurs when the coating fills in the
lettering or logo on the tablet and is
typically caused by improper
application of the solution, poor design
of the tablet embossing, high coating
viscosity, high percentage of solids in
the solution, or improper atomization
pressure.
During drying, the film may shrink and
pull away from the sharp corners of an
intagliation or bisect, resulting in a
bridging of the surface. This defect can
be so severe that the monogram or
bisect is completely obscured. Remedy:
Increasing the plasticizer content or
changing the plasticizer can decrease
the incidence of bridging.
Twinning is a form of over
wetting whereby two or
more of the tablet cores
are stuck together. This
situation is prevalent
when attempting to coat
flat faced or caplet-
shaped tablets
. Placing even a very
subtle amount of
curvature on an otherwise
flat surface can minimize
twinning problems.

55. REFERENCES
Industrial pharmacy-1 by Dr.
Shalini Sharma , PV publication
Aulton’s pharmaceutics – THE DESIGN
AND MANUFACTURE OF MEDICINES by
Michael E. Aulton and Kevin M.G.
Taylor, 4th edition
The Theory and practice of
Industrial pharmacy by- Roop K
Khar, Farhan J Ahmed, Gaurav K
Jain , SP Vyas, Lachman/
Lieberman production

56. Thank you…