Tablet Coating

Question 1

Describe polymer film (IR) coating

Answer 1

Wet process

Question 2

Describe sugar coating

Answer 2

Wet process
Traditional + cheap

Question 3

Describe compression coating

Answer 3

Dry process

Question 4

Describe the type of film coating for immediate release

Answer 4

Side chain hydrophilic
Soluble in stomach = ionise at low pH

Question 5

Describe the type of film coating for delayed release

Answer 5

Insoluble in stomach = acidic
Dissolve in small intestine

Question 6

Describe the type of film coating for extended release

Answer 6

Insoluble in H2O = hydrophobic

Question 7

Describe film coating method

Answer 7

Atomised coating formulation sprayed on to tablet
Tablets coated in a coating drum
Particles coated in fluidised bed coater = formulate sprayed below suspended particles

Question 8

What are the advantages of film coating?

Answer 8

Protect dosage form
Range of coating excipients
Single-step process
Thin coatings = minimum weight
Retains tablet shape + surface features

Question 9

What are the disadvantages of film coating?

Answer 9

High cost + footprint
Use of organic solvents may pose potential hazards

Question 10

What are the advantages of sugar coating?

Answer 10

Inexpensive
Safe/accepted raw materials

Question 11

What are the disadvantages of sugar coating?

Answer 11

Significant weight gain
Water-soluble coat = IR only
Multi-step process
Alters shape of tablets
Embossing not possible

Question 12

Describe the sugar coating steps

Answer 12

Sealing = waterproof core = layers of polymer
Subcoating = apply 3-5 layers of sucrose syrup
Smoothing = apply 5-10 layers of sucrose syrup
Colouring = apply several coats of thin syrup with colourant
Polishing = apply wax for glossy appearance
Printing = print text or symbols in edible ink

Question 13

Describe bridging (film-coating defect)

Answer 13

Film coating lost indented markings
Caused by film shrinkage upon drying

Question 14

Describe orange peel effect (film-coating defect)

Answer 14

Uneven spreading
Caused by incorrect atomisation or spray rate

Question 15

Describe core erosion (film-coating defect)

Answer 15

Disfigurement of tablet surface
Cause by over-exposure to formulation

Question 16

Describe cracking (film-coating defect)

Answer 16

Fissure in film coating
Caused by insufficient mechanical strength, insufficient plasticiser + thermal expansion of tablet

Question 17

Describe peeling (film-coating defect)

Answer 17

Film coating lifts off tablet surface
Caused by insufficient adhesion between film + tablet

Question 18

Describe twinning (film-coating defect)

Answer 18

Tablets stick together along the edges
Caused by coating formulation that is too viscous or inefficient drying

Question 19

How do you reduce twinning?

Answer 19

Circular/oval tablets reduce it

Question 20

What type of process is compression coating?

Answer 20

Dry process

Question 21

What is the problem with compression coating?

Answer 21

Expensive + complex

Question 22

How can delayed drug release be achieved via compression coating?

Answer 22

Change the ratio of sodium alginate
Change coating thickness

Question 23

What happens if you increase the amount of sodium alginate?

Answer 23

Longer the delay

Question 24

What happens if you increase thickness of the coating?

Answer 24

Longer the delay