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Copyright©
2004 Pformulate.
All
rights reserved.
Books
About Coating:
Pharmaceutical
Coating Technology Pharmaceutical
Unit Operations: Coating (Drug, Manufacturing Technology, Series V.3) |
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| 1] What is Film Coating?
Film coating is the process
whereby a tablet, capsule, or pellet is surrounded by a thin layer of
polymeric material. |
| 2) Reasons for
film coating include: |
| Appearance |
To change the color, for branding purposes or other
aesthetic reasons |
| Stability |
To protect the active ingredient from moisture, light,
and/or the acidic environment of the stomach |
| Taste/odor Masking |
To provide an easy to swallow tablet without the bitter
taste of many actives |
| Release characteristics |
Many film coating materials have functional properties
which enable the creation of sustained or delayed (enteric) release
dosage forms |
3) The basic components of a film
coating system are:
 | optional ingredients:
 | anti-tack agent |
| anti-foam agent |
| colorant |
| filler/extender |
| flavorant |
| surfactant |
|
|
|
4]
Film coatings are available based on the following polymeric materials:
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Cellulose
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Cellulose
Acetate Phthalate |
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Hydroxypropylmethylcellulose |
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Hydroxypropylcellulose |
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Hydroxypropylethylcellulose |
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Ethylcellulose |
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Methylcellulose |
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Microcrystalline
Cellulose and Carrageenan |
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Methacrylic
acid/methacrylate esters
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Anionic
and Cationic polymers of Methacrylic Acid |
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Copolymers
of methacrylates
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Copolymers
of Acrylates and Methacrylates
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Copolymers
of Ethacrylate and Methylmethacrylate
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|
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Polyvinylacetate
phthalate
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Shellac |
Most
of these materials are available as the individual powders, but many are
also available in premixed powder blends, powder concentrates and
aqueous dispersions.
Dry
powder concentrates for reconstitution combine polymer, plasticizer and if desired, pigment in a
single system for either aqueous or organic coating
procedures, which reduces inventory handling and raw material testing.
Aqueous based
coating systems including the aqueous dispersions have become popular in
recent years since they are solvenet free and more environmentally
friendly. Most polymers
are now available for reconstitution in water, or as an aqueous
dispersion.
Points to
consider in the preparation and use of coating solution/dispersions:
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Ensure
complete and uniform dissolution/dispersion of all coating
ingredients throughout the coating process |
|
Maintain
viscosity of coating solution/dispersion throughout the coating
process |
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Keep fluid
lines free of any aggregates of solid material throughout the
coating process. |
|
Limit the
amount of air entrapment/foam creation during coating
solution/dispersion preparation and throughout the coating process |
|
| |
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Products for Immediate Release include:
Cellulose-based coating materials
Methacrylate-based coating materials
Products for Sustained Release include:
Cellulose-based coating materials
Methacrylate-based coating materials
Products for Enteric coating include:
Cellulose-based coating materials
Methacrylate-based coating materials
Shellac
Need a
supplier? Submit in Excipients
Express!!!
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5) Coating Processes and
Equipment
The majority of tablet film coating is performed in perforated closed
system pans. These provide the necessary controlled conditions of temperature
and air flow which enable reproducible and efficient application of both
appearance and functional coatings. In addition, they limit operator exposure.
In choosing a system for film coating, the following points should be
addressed:
| Adequate supply of process air for the volume of the pan. |
| Ability to maintain temperature within a narrow range (typically 30 to
70șC). |
| Ability to maintain dew point within a narrow range (typically 10 -
20șC). |
| Pan and spray system designed to be easily cleaned/sanitized. |
| Spray system fluid path should have a minimum of dead spaces, since many
coating formulations are dispersions or suspensions. |
| Spray system atomization and fan air are easily controlled, preferably
from the exterior of the pan. |
| Air flow bypass capability (especially if the pan is to be used for
sugar coating. |
| Explosion prevention construction if flammable solvents are to be used. |
| Treatment of Inlet and Exhaust Air as required by GMP and environmental
regulations. |
The pan should be equipped with appropriate sensors so that the following
conditions can be monitored/controlled:
| Pan rotational speed |
| Inlet air temperature |
| Inlet air dew point |
| Inlet air flow rate |
| Spray system atomization and fan air flow rate |
| Coating liquid spray rate |
| Exhaust air temperature |
| Product temperature |
Equipment Suppliers for perforated pans:
Iriam
LB Bohle
Nicomac
O'Hara Technologies, Inc.
Thomas Engineering
Vector Corporation
Werner and Mathis
Equipment Suppliers for fluid bed coating systems:
Fluid Air, Inc.
Glatt
LB Bohle
Contract Coating Services
Kali Pharmaceuticals
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Pformulate/01/02/2003
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