Polymers: Oral Transmucosal Delivery

Question 1

Define: Buccal delivery

Answer 1

Drug is administered through the mucosal membranes lining the cheeks (buccal mucosa)

Question 2

Define: Sublingual delivery

Answer 2

Drug is delivered through the mucosal membranes lining the floor of the mouth

Question 3

Define: Gingival delivery

Answer 3

Drug is delivered through the gingiva (gums)

Question 4

Describe keratinised epithelium

Answer 4

Part of the oral epithelium
Dehydrated, mechanically tough and chemically resistant
Found in the areas subjected to mechanical stress e.g. gingiva (gums) and hard palate (roof of mouth)

Question 5

Describe non-keratinised epithelium

Answer 5

Part of the oral epithelium
Relatively flexible
Found in soft palate, floor of mouth, lips and cheeks

Question 6

What is saliva made up of?

Answer 6

A hypotonic secretion composed of:
Water
Proteins and enzymes = amylase, micins, lysozyme
Inorganic salts

Question 7

What is the pH of saliva?

Answer 7

Between pH 6.2 and 7.4

Higher pH on increased secretion

Question 8

List the 4 functions of saliva

Answer 8

1. Lubrication
2. Digestion of food (amylase in saliva beaks down some starches)
3. Protection (lysozyme acts to lyse bacteria)
4. Speech

Question 9

Why are some drugs delivered via the buccal route?

Answer 9

There is a rich blood supply in the oral cavity

= greater bioavailability

Question 10

List 3 differences between buccal and sublingual drug delivery

Answer 10

1. Sublingual has a higher permeability than buccal
2. Sublingual has more rapid absorption compared to buccal
3. Sublingual is thinner than buccal

Question 11

Describe the structure of the buccal mucosa

Answer 11

Oral epithelium > Basement membrane > Papillary layer . Reticular layer > Submucosa

Question 12

What differs in the cells as they get further towards the cavity?

Answer 12

• Cells become larger in size
• More flattened cells
• Contain more proteins
• Less viable cells (actively growing/dividing)

Question 13

What is LogP?

Answer 13

The partition coefficient

Question 14

Describe the relationship between LogP and buccal absorption

Answer 14

As LogP increases, so does buccal absorption

Question 15

How can a drug cross the buccal membrane?

Answer 15

In order to cross the phospholipid cell membrane, the drug should:
Be in the lipid-soluble or unionised form
Be in solution
Have a relatively low MW
Exhibit biphasic solubility patterns (soluble in aqueous salivary fluid and lipid membrane barrier to penetration)

Question 16

What is the route of drugs taken when administered via the buccal route?

Answer 16

Solid drug powder or tablet dissolved in buccal fluids
Dissolved drug in buccal membrane
Either travels to lymphatic circulation then blood or straight to blood circulation

Or drug can be removed from the oral cavity by swallowing

Question 17

What are the indications of nitroglycerin (glyceryl trinitrate)?

Answer 17

Prophylaxis of angina and left ventricular failure

Question 18

How is GTN spray administered?

Answer 18

Sublingual route

Tablets, lipid aerosol formulations and capsules

Question 19

Explain nitroglycerin tablets

Answer 19

GTN is highly effective in tablet form - relieves pain quickly
Probelms with stability - heat, light and moisture- sensitive
Also, effect is short-lived (1 hour)

Question 20

How is the effect of GTN extended?

Answer 20

Sustained release buccal GTN = rapid onset and prolonged effect in a single formulation
Formulated using mucoadhesive cellulose fibres

Question 21

What are the 2 types of patches used to deliver drugs via the buccal route?

Answer 21

1. Multi-directional release patch

2. Unidirectional release patch (has an impermeable backing)

Question 22

List 2 disadvantages of using a multi-directional release patch

Answer 22

1. The drug becomes substantially diluted in the saliva

2. Drug is not protected from the physical environment

Question 23

List 2 disadvantages of using a uni-directional release patch

Answer 23

1. Available adsorption area is quite small

2. The presence of the backing layer may decrease flexibility and cause patient discomfort

Question 24

List 3 requirements of mucoadhesive buccal films

Answer 24

1. Flexibility, elasticity, softness
2. Good mucoadhesive ability to be retained in the mouth for a desired duration
3. Adequate strength to withstand breakage due to stress from mouth activities

Question 25

List 3 advantages of using buccal/sublingual/gingival administration

Answer 25

1. Avoids exposure of drug to GI system
2. Bypasses liver (prevents 1st pass metabolism = greater bioavailability)
3. Rapid absorption possible

Question 26

List 3 disadvantages of using buccal/sublingual/gingival administration

Answer 26

1. Relatively small absorptive surface area
2. Less permeable than small intestine
3. Taste of drug