Green: Advanced Coating

Question 1

What is the purpose of coating tablets?

Answer 1

1. Aesthetics: can hide the colours
2. Mask taste: sweeteners
3. Different release times: slow release to protect tablets from stomach
4. Protect the API
5. Mechanical strength

Question 2

What are the three different types of coatings on tablets?

Answer 2

1. Enteric
2. Film
3. Sugar

Question 3

In the tableting manufacturing process, where does coating appear?

Answer 3

1. Near the end

2. Before packaging

Question 4

How are coatings added to the tablet?

Answer 4

1. Coating is in solution and sprayed onto the tablet

2. Dried on the surface of tablets and particles

Question 5

What are the advantages of sugar hard coatings?

Answer 5

1. Coats the central core of the tablets to mask taste in drugs which are unpleasant tasting (ibuprofen)
2. Protects the active from both light and moisture so it improves stability
3. Increases the size of tablet (disadvantage for relatively large tablets)

Question 6

What are the two examples of excipients that add sweetness?

Answer 6

1. Sucrose

2. Glycerol

Question 7

What are the three examples of excipients that add mechanical strength?

Answer 7

1. Croscarmellulose Sodium
2. Gelatin
3. Gum Arabic

Question 8

What is the disadvantage of sugar coating?

Answer 8

Can delay the rate of dissolution and disintegration

Question 9

Describe the purpose of a film coating?

Answer 9

1. Thin layers of inactive excipients thinly coated onto the tablets
2. Acts the same as sugar coating to mask flavour to protect it from sunlight and moisture
3. Dissolves very quickly with contact with an aqueous environment or mechanical damage

Question 10

What are examples of polymers to create the film coat?

Answer 10

1. HPMC
2. Shellac
3. Methylcellulose
4. Polyvinylacetate phthlate

Question 11

What are examples of solvents used to create the film coat?

Answer 11

1. Water: high surface tension
2. Alcohols: ethanol
3. Ketones: acetone
4. Chlorinated Dichloromethane (DCM)

Question 12

What are examples of plasticisers used to create the film coat and the reason why they are used?

Answer 12

1. Adds mechanical flexibility
2. Lowers glass transition temperature between polymer chains to increase free volume, elasticity and softness of film
3. Examples: PEG and citrate containing esters

Question 13

What are examples of colourants, flavours and anti-tack agents that are used to create the film coat?

Answer 13

1. Colouants: Organic or inorganic colourants
2. Flavours: Asparatimine Fruit Spirits
3. Anti-tack Glycerol monostearate (GMS) and talc

Question 14

How is the dissolution profile affected by film coating?

Answer 14

Not affected much at all due to the thickness being very thin

Question 15

What is the purpose of sustained release tablets?

Answer 15

1. Alter release from dosage form and provides a more sustained release of active thoughout the time it’s in the body or to protect it
2. Increases the time for the GI tract to absorb it, mainly the small intestine that absorbs most drugs

Question 16

What is the standard dosing in terms of drug concentration and time in the body?

Answer 16

Initially the drug concatenation increases as time goes by but as soon as it reaches it’s half life there’s a decrease

Question 17

What can repeat action of the dosing do?

Answer 17

Determines which coating will delay the release

Question 18

Describe what delayed release is?

Answer 18

Release of API is delayed from transmission in the stomach (enteric)

Question 19

Describe what repeat action release is?

Answer 19

The coating will allow the tablet to release it’s API for a second time round to allow for continuous effect

Question 20

Describe what prolonged/sustained release is?

Answer 20

Takes longer to get to the required therapeutic

Question 21

Describe what constant release is?

Answer 21

Constant rate release and constant plasma concentration

Question 22

What is the reason behind modified release tablets?

Answer 22

1. Less change in blood levels
2. Reduces frequency of dosing
3. Reduced side effects
4. More convenience and increases compliance to take drug
5. Reduction in health care costs

Question 23

What must patients show in order to be eligible for modified release tablets?

Answer 23

1. Must exhibit neither slow or fast rates of absorption
2. Must be uniformly absorbed to control the blood levels by the drug itself
3. Must be administered in small doses
4. Must have a good margin of safety
5. For chronic rather than acute conditions

Question 24

Describe what enteric coating is?

Answer 24

1. Relating to or occurring in the intestines
2. Delays the breakdown of the tablet until it reaches the small intestine (pH dependent depending on area of tablet)
3. Surrounds the API core with excipients

Question 25

Describe the purpose of the duodenum?

Answer 25

1. Site of most chemical digestion 2. Usually contains the chemicals produced by the liver, gall bladder and pancreas over here 3. Absorption of vitamins, minerals and other nutrients (especially iron) 4. Residency time is relatively short so may not be the best area for drug absorption (1 hour)

Question 26

Describe the purpose of the Jejunum?

Answer 26

1. Mucosa surface is covered in villi 2. Best area for nutrient absorption 3. Good vascular supply 4. Slight increase in pH compared to duodenum

Question 27

Describe the purpose of the ileum?

Answer 27

1. Smaller in diameter and thicker walls than the other areas of intestine 2. Main role is to absorb vitamin B12 and bile salts 3. Contains peyers patches that contain large amounts of lymphocytes

Question 28

Why do we enterically coat tablets?

Answer 28

1. Local or systemic action 2. Protects the stomach from the drug 3. Allows the acid to not react with the drug so it can travel to the intestines 4. Improved bioavailability

Question 29

Give examples of different forms of enteric coatings?

Answer 29

1. Cellulose acetate phthalate 2. Polyvinyl acetate phthalate 3. Acrylates (Eudragit)

Question 30

How does enteric coated tablets affect dissolution and disintegration?

Answer 30

Directly affects disintegration and dissolution depending on the rate the patient absorbs the tablet

Question 31

Give examples of drugs that are commonly used as enteric coatings and why?

Answer 31

1. Aspirin and naproxen: dissolves in the stomach acid and can cause stomach ulcers 2. Omeprazole: broken down in stomach acid and activates in the small intestine 3. Sulfasalazine: treatment of arthritis (drug has to dissolve in stomach) and Crohn's disease (drug has to dissolve in small intestine)

Question 32

Give examples of polymers that are used to form enteric coatings?

Answer 32

1. Shellac 2. Cellulose acetate phthalate 3. Hypromellulose phthalate 4. Methacrylic acid (Cover pH range of 4.5 to 7)

Question 33

What are Eudragits?

Answer 33

1. Name for a family of polymers with varying properties | 2. Can be a carboxylic acid or ester depending on the situation

Question 34

How are Eudragits applied in reality when it comes to drugs?

Answer 34

1. When there's an increase in pH, it loses it's H+ and becomes more soluble 2. When in ester form, it's more hydrophobic so it takes longer to dissolve

Question 35

Explain the disintegration test for E/C tablets?

Answer 35

1. Introduce one tablet into each tube 2. Place in 0.1M HCl and leave for 2 hours (Check for no cracks) 3. Place in phosphate buffer 6.8 pH and leave for 1 hours 4. Tablets pass the test if all six have disintegrated

Question 36

Explain how repeat action tablets work?

Answer 36

1. Two layer of tablets that are separated by enteric coating 2. First dose gives a rapid onset of action 3. Enteric coating delays the second doses onset of action