Particle coating involves applying a thin layer around core particles to enhance their properties and functionalities. Various methods such as solvent coating, aqueous coating, and solvent-less techniques like photocurable and hot-melt coating are utilized, each with specific advantages and disadvantages. The goal of these methods is to improve flowability, protect sensitive substances, and control the release of active pharmaceutical ingredients.

1. Partical Coating:

2. DEFINITION:
• When a thin layer of a substance is placed around a core particle it is
called coating of the particle.
• Coating alters:
• Surface Properties &/or Functionality
of fine particles or powders.

3. 
Coating layer is generally applied as:
Film resulting from the spraying &
Subsequent drying of solutions or dispersions

4. Purpose of Coating:
Improvement to powder Flowability.
Protection of Unstable/Reactive Substances (from Air, Humidity, Light
& Oxidation etc.)
Enhancement of Mechanical Properties (Abrasion Resistance &
Compressibility)
Improvement of Aesthetic Appeal (Texture, Appearance, Odor or
Taste Masking)
Controlled Release / Dissolution of APIs.

5. Methods of Partical coating
Wet / Liquid Coating Methods
Solvent Coating Aqueous Coating

6. 1. Solvent Coating:
 Coating polymers & other excipients are dissolved into an
organic solvent to form a coating solution
 Coating solution is sprayed onto the surface of the solid dosage
forms to form a coating film by evaporating the organic solvent.
 Evaporation is done by drying process resulting in uniform film
formation.
• Disadvantages:
Toxicity and environmental concerns due to presence of
organic solvents

7. • TECHNOLOGIES:
o Microencapsulation
o Fluidized bed coating techniques
o Solvent evaporation
o Coacervation & phase separation techniques
o Spray drying
o Interfacial polymerization
o Pan coating

8. 2. Aqueous Coating
• A preferred approach over solvent coating
 For water soluble polymers:
• The coating process & film formation mechanism
are SAME as organic solvent coating.
 For water-insoluble polymers:
• The coating process & film formation mechanism
are DIFFERENT.

9. • Advantages:
 No toxicity
 No environment related problems
• LIMITATIONS:
Water is more difficult to be evaporated compared to the organic
solvents.
Much longer processing time
Much higher energy consumption
Hot air handling
Not appropriate for the moisture sensitive drugs

10. Solvent-less Coating Methods
Purpose:
Solventless Coating Technologies can overcome following
disadvantages associated with use of solvent/water in coating
process:
Organic solvents used in liquid coating are Flammable & Toxic.
Solvent vapors causes hazards to coating operators,
Solvent residue in the formulation.
High cost of solvents
Strict Environmental & Occupational Safety Regulations.

11. Heat & water involved in coating process can degrade the drug
Validation of coating dispersion for controlling microbial presence
Solvent removal processes is time consuming
Extreme energy consumption in solvent removal process.

12. Solvent less Coating Methods
• No drying or liquid/solvent evaporation step
A. Photocurable Coating
B. Compression Coating
C. Hot-melt Coating
D. Magnetically assisted impaction Coating
E. Powder/Dry Coating
F. Supercritical Fluid Coating

13. A. Photocuring Coating
• PHOTOCURING:
• A process of rapid conversion of specially formulated
(usually liquid) solventless compositions into solid
films by irradiation with UV or Visible Light
• UV-more energetic, Visible light is preferred due to
safety & ease.
• The only chemical approach to form coating film.

14. • Advantages:
 This process can be performed at or below room
temperature with an extremely rapid rate.
 Coating can be done in open systems i. e. Pan Coating.
• Disadvantages:
 Not suitable for photosensitive drugs
 Use is limited by specific photocurable materials and
coating equipment.

15. B. Compression Coating
• Mixture of core formulation is
first compressed into an inner
layer CORE and then coating
material is compressed around
the core to form an Outer Layer.

16. •
Advantages:
Two incompatible drugs within same Dosage Form (Physically separated)
Disadvantages:
Mechanically complex method; requires specially designed equipment.
Coating thickness is not uniform; issues of placement of core in the centre

17. C. Hot Melt Coating:
• Coating materials are applied over the Substrate in their Molten state
& then solidified upon cooling.
• Coating Materials: Lipids, Waxes & Fatty bases.
• Weight gain with lipid materials are less than those commonly
applied with polymers to achieve same effect.

18. Hot Melt Coating:

19. • Advantages:
 Necessity of solvent application is fully eliminated.
 Cost effective
• Disadvantages:
 Only suitable for the drugs with stable properties at or
below congealing point of coating materials.
 Operational safety: high temperature close to 2000 ˚C.

20. D. Magnetically Assisted Impaction Coating:
•Soft coating method(s)
• That attach the Guest particles (Coating material) on the host particles
(material to be coat) with a minimum degradation of particle size, shape
and composition caused by the build up of heat.
• Advantages:
 Rise in temperature is negligible.
 Most suitable for temperature sensitive particles
• MAIC Device:
• It can coat soft organic host and guest particles without causing
major changes in material shape & size.

21. Mechanism of coating in MAIC Process
a) Excitation of magnetic particles
b)De-agglomeration of guest
particles
c) Shearing & spreading of guest
particles on surface of host
particles
d)Magnetic-host-host particle
interaction
e) Magnetic-host wall interaction
f) Formation of coated products

22. E. Powder/Dry Coating:
•Dry coating refers to the technique where the core materials are
strongly surrounded by fine particles simply by collision or by the use of
non-aqueous plasticizer
•Dry Coating Techniques
I. Plasticizer Dry Coating
II. Heat Dry Coating
III.Electrostatic Dry Coating

23. F. Supercritical Fluid Coating:
• Used to coat small particles uniformly by encapsulating each core with coating materials
uniformly under Supercritical Conditions.
• Advantages:
Mild processing conditions
Allows microencapsulation of sensitive ingredients e.g Albumin.
Prevent agglomeration of fine particles during coating.
• Disadvantages:
Application is limited due to the poor solubility of most of coating materials in
supercritical fluid.
Requirement of the core to be insoluble.

24. THANKS