Film coating

Question 1

Reasons to apply coating

Answer 1

1) Improve appearance
2) Taste making
3) Stability (moisture, o2, and light barriers)
4) To confer mechanical strength
5) To facilitate handling of the tablets on production lines
6) Modify drug release

Question 2

Types of coating

Answer 2

Sugar coating
Film coating
Other coating methods (Compression/ electrostatic and gelatin)

Question 3

Fim coating

Answer 3

1) Immediate release

2) Modified release ( enteric, sustained)

Question 4

Component in a film coat

Answer 4

Film former 
Solvents 
Plasticisers 
Colourants 
Anti- tacking agents

Question 5

Polymers of immediate release film coating

Answer 5

Hydroxypropyl methycellulose (HPMC)
Methylcellulose (MC) and hydroxypropyl cellulose (HPC)
Vinyl derivatives (PVP and PVA and vinyl acetate)

Question 6

Polymers for modified release film coating (enteric)

Answer 6

Metharcylic acid copolymers
Cellulose based polymers (cellulose acetate pthalate)
Polyvinyl derivatives (polyvinyl acetate pthalate)

Question 7

Reasons for using enteric coated tablets

Answer 7

1) Prevent degradation of acid sensitive API
2) Prevent irritation of stomach and certain drugs
3) Delivery of API into specific site of the intestine for localised disease

Question 8

How does enteric coating work

Answer 8

1) Contains COOH group in the polymer structure
2) Unionized and insoluble at the low pH of the stomach
3) pH dependent dissolution and drug release

Question 9

Polymers for modified release sustained release

Answer 9

• Ethyl cellulose

- Polymethacrylate polymers (pH dependent Eudragits)

Question 10

What are plasticizers

Answer 10

Small molecules that interpose themselves on a molecular stage between polymer strands.

Question 11

How do plasticizers work

Answer 11

• Decrease friction between film forming polymers
• Decrease glass transition temperature
• Increase film flexibility and decrease film brittleness

Question 12

Examples of plasticizers

Answer 12

Polyethylene glycol (PEG)
Organic esters
Oil/glycerides

Question 13

How do Anti tacking agents work

Answer 13

Prevent stickiness during coating

Question 14

Examples of anti tacking agents

Answer 14

Talc (10-50%) 
Glycerol monoesterate (GMS 2-5%)

Question 15

Use of colorants

Answer 15

Provide elegant appearance

Some have light protective properties.

Question 16

Examples of colorants

Answer 16

Iron oxide pigments
Titanium dioxide
Aluminium lakes.

Question 17

Film coating process (4)

Answer 17

1) Spray - coating liquid (solution and suspension)
2) Deposit - liquid droplets onto the cores
3) Film formation - a thin layer of film is formed due to solvent evaporation
4) Drying - Further removal of the solvent leaves to dry film around the core

Question 18

Examples of film coating

Answer 18

Pan coater 
Fluidised bed coater 
Particle coalescence
Compression coating 
Electostatic coating 
Vacum film coating 
Sugar coating

Question 19

Pan coating

Answer 19

Pan speeds keep tablet tumbling and then sprayed, via inlet and outlet air temperature
Temperature cant be too hot - solution dries before it hits the tablet
or too cold - evaporation does not occur from the tablet surface.

Question 20

Sugar coating

Answer 20

1) Sealing
2) Sub - coating
3) Smoothing
4) Colouring
5) Polishing
6) Printing