Tablet Coating technology ppt

TABLET COATING
TECHNOLOGY
submitted by
Y. AKHILA(Y18MPH352)
Under the guidance of
Dr. P. ROHINI MADAM
Department of pharmaceutical sciences
A. N. U College of pharmaceutical sciences

CONTENTS
 Introduction
 Equipment
 Tablet coating process
 Film defects in tablet coating
 Reference

TABLET COATING
The application of coating to tablets, which is an additional
step in the manufacturing process, increase 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 physical and mechanical protection for the drug.
 To control the release of drug from the tablet.
 To protect the drug from the gastric environment of the
stomach with an acid-resistant enteric coating.

EQUIPMENT
 STANDARD COATING PAN
• IMMERSION SWORD SYSTEM
• IMMERSION TUBE SYSTEM
• PELLIGRINI PAN SYSTEM
 PERFORATED COATINF PAN
• ACCELA-COTA SYSTEM
• HI- COATER SYSTEM
• DRIACOATER
 FLUIDIZED BED SYSTEMS

STANDARD COATING PAN
 It consists of a metal pan
which is 8 to 60 inches in
diameter and is rotated on its
horizontal axis by a motor.
 Heated air is directed into the
pan and onto the tablet bed
surface, and is exhausted by
means of ducts positioned
through the front of the pan.
 Coating solutions are applied
to the tablets by spraying the
material onto the rotating
tablet bed.

Immersion tube system
 The tube is immersed into the
tablet bed.
 The tube delivers the heated
air, and a spray nozzle is built
in the tip of the tube.
 During this operation, the
coating solution is applied
simultaneously with the
heated air from the immersed
tube.
 The drying air flows upward
through the tablet bed and is
exhausted by a conventional
duct.

Immersion sword system
 Drying air is introduced
through a perforated metal
sword device that is immersed
in the tablet bed.
 The drying air flows upward
from the sword through the
tablet bed.
 Coating solution are applied
by an atomized spray system
directed to the surface of the
rotating tablet bed.
Pellegrini pan system
It has a baffle pan and a diffuser
that distributes the drying air
uniformly over the tablet bed
surface.

 In the Accela - Cota and Hi-
Coater systems, drying air is
directed into the drum, is
passed through the tablet bed,
and is exhausted through
perforations in the drum.
 Driacoater introduces drying
air through hollow perforated
ribs located on the inside
periphery of the drum.
 As the coating pan rotates the
ribs dip into the tablet bed,
and drying air passes up
through and fluidizes the
tablet bed. Exhaust is from the
back of the pan.

FLUIDIZED BED SYSTEM
 Fluidization of the tablet mass is achieved in a columnar chamber
by the upward flow of drying air.
 The air flow is controlled so that more air enters the center of the
column, causing the tablets to rise in the center.
 The movement of the tablets is upward through the center of the
chamber.
 They then fall towards the chamber wall and over downwards to re-
enter the air stream at the bottom of the chamber.
 In some units, a smaller columns is used to direct tablet movement
within the main column.
 Coating solutions are continuously applied from a spray nozzle
located at the bottom of the chamber or are sprayed onto the top of
the cascading tablet bed by nozzles located in the upper region of
the chamber.

TABLET COATING PROCESSES
 The type of process chosen depends on the type of coating that is
applied, the durability of the tablet core, and the economics of the
process.
1. SUGAR COATING
2. FILM COATING
3. ENTERIC COATING
4. SPECIALIZED COATING
e.g. compression coating
electrostatic coating
Dip coating
Vacuum Film coating

 Seal coating: To prevent moisture penetration into the tablet core, a
seal coat is applied. Without a seal coat a over wetted tablets would
absorb excess moisture, leading to tablet softening or disintegration
and affecting the physical and chemical stability of the finished
product.
e.g. Zein is an alcohol-soluble protein derivative from corn that
has also been used as an effective sealant.
• Subcoating: The subcoating is applied to round the edges and build
up the tablet size. Sugar coating can increase the tablet weight by 50
to 100%. Subsequent subcoats are applied in the same manner until
the tablet edges have been covered and the desired thickness is
achieved.
• Smoothing/ color coating: The purpose of the coat is to cover and
fill in the imperfections in the tablet surface caused by the
subcoating step, and to impact the desired color to the tablet.

 Polishing: The desired luster is obtained in this final
coating process. The tablets can be polished in clean
standard coating pans by applying beeswax or carnauba
wax.

FILM COATING
Materials used in film coating
 Film formers:
e.g. Hydroxypropyl methylcellulose,
Methyl Hydroxyethylcellulose,
Ethyl cellulose, povidone etc.
 Solvents : important considerations of 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 systems.
 It should be colorless, tasteless, odorless, inexpensive, nontoxic,
inert.
 The most widely used solvents either or along with combination are
water, ethanol, acetone, chloroform etc.

 Plasticizers : these are generally added to film coating formulations
to modify the physical properties of the polymer to make it more
usable. One important property is their ability to decrease film
brittleness.
 E.g. castor oil, propylene glycol, glycerin, polysorbates, sorbitan
esters.
 Colorants : They are used to provide distinctive color and elegance
to dosage form.
E.g. Opalux- Opaquant color concentrate for sugar coating.
Opaspray- Opaque color concentrate for film coating.
Opadry- Complete film coating concentrate.

ENTERIC COATING
 To protect acid-labile drugs from the gastric fluids, e.g. enzymes
and certain antibiotics.
 To prevent gastric distress or nausea due to irritation from a drug,
e.g. sodium salicylate.
 To deliver drugs intended for local action in the intestine.
Ideal properties:
 Resistance to gastric fluids.
 Nontoxicity.
 Low cost.
 The film should not stain
on coating.

FILM DEFECTS IN TABLET COATING
Sticking and picking :
 Over wetting or excessive film
tackiness causes tablets to stick to each
other or to the coating pan.
• A reduction in the liquid application
Rate or increase in the drying air
Temperature and air volume usually
Solve the problem.
Roughness :
A rough surface is a defect often
observed when coating is applied by a spray
 Reducing the degree of optimization can
Decreases the roughness due to spray drying.

Capping is partial or complete separation
of top or bottom crowns of tablet main
body. Lamination is separation of a tablet
into two or more distinct layers. Friability
test can be used to reveal these problems
 Orange peel effect:
Inadequate spreading of the coating Solution before drying causes a
orange peel Effect. Thinning the solution with additional Solvent may
correct this problem.
Capping and Lamination:

Bridging :
 During drying, the film may shrink and pull away from the sharp
corners of an bisect, resulting in a bridging of the surface
depression.
Cracking:
Cracking occurs if internal stresses in the film exceed the tensile
strength of the film. Internal Stresses in the film can be minimized by
adjusting type and concentration

REFERENCES
 The theory and practice of Industrial Pharmacy by Leon
Lachman and Lieberman. Special Indian Edition 2009
Pg. 346 to 372.

Tablet Coating technology ppt

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