Polymers: Mucoadhesive Dosage Forms

Question 1

Define: Muscoadhesion

Answer 1

Interfacial force between a synthetic or natural polymeric material serving as a dosage form and a mucus layer that covers a mucosal tissue
= There is attraction between the natural mucous layer and the synthetic polymer forms

Question 2

List 3 advantages of mucoadhesive delivery

i.e. using a polymer to adhere to mucosal membranes

Answer 2

1. Increased dosage form residence time
2. Improved drug bioavailability (as longer residence time)
3. Reduced administration frequency (as higher bioavailability)

Question 3

Describe the structure of mucosal membranes

Answer 3

Layer of soluble secreted mucins
Layer of cell-bound mucins
Epithelial cells

Question 4

Describe the structure of the mucins found on the mucosal membrnes

Answer 4

Protein core
Oligosaccharide side chains
Terminal sialic acid at end of side chain

Question 5

Define: Mucin

Answer 5

Principle component of mucous

Mucopolysaccharide or glycoprotein

Question 6

List 4 functions of mucosal membranes

Answer 6

1. Protection of epithelial cells from physical and chemical destruction
2. Lubrication
3. Wetting
4. Modulation of water content in the underlying tissues

Question 7

Describe the characteristics of mucosal surfaces

Answer 7

• Dynamic surface that is reformed continuously through the secretion of mucins
• Relatively short life time as constantly moving and being replaced
• Efficient semi-permeable barrier system

Question 8

How is mucous constantly moved on?

Answer 8

Ciliary cells beat in a formulated fashion

Clears mucous into stomach to be digested

Question 9

List the 4 theories of mucoadhesion

Answer 9

1. Electronic theory
2. Absorption theory
3. Diffusion theory
4. Wetting theory

Question 10

Describe the electronic theory of mucoadhesion

Answer 10

Electron transfer between the formulation and mucus result in formation of an electrical double layer at the interface

Question 11

Describe the absorption theory of mucoadhesion

Answer 11

Attraction between mucus and mucoadhesive dosage form is achieved via molecular bonding caused by secondary forces such as hydrogen bonding and Van der Waals forced

Question 12

Describe the diffusion theory of mucoadhesion

Answer 12

Inter-penetration and physical entanglement of the mucus protein and polymer chains of the dosage form

Question 13

Describe the wetting theory of mucoadhesion

Answer 13

Correlates the surface tension of the mucus and the mucoadhesive with the ability of the mucoadhesive to swell and spread on the mucous layer

Question 14

List the stages of mucosal adhesion

Answer 14

1. Contact stage = contact, swelling and wetting

2. Consolidation stage = non-covalent bonds formation, diffusion and inter-penetration

Question 15

List 3 advantages of using sources of animal tissue (slaughterhouse material) to test the performance of mucoadhesive dosage forms

Answer 15

1. No need to breed and kill animals
2. Cost efficiency
3. No problems with animal activists

Question 16

List a disadvantage of using sources of animal tissue (slaughterhouse material) to test the performance of mucoadhesive dosage forms

Answer 16

Tissues are not always fresh

Question 17

List 4 ways that the performance of mucoadhesive dosage forms can be tested

Answer 17

1. In man
2. Animal testing
3. Sources of animal tissue
4. Visual methods = flow cell method or rotating cylinder method

Question 18

What occurs in the flow cell method?

Answer 18

Artificial body fluid solution is run down a slope containing the dosage form and mucosal tissue to test retention time

Question 19

What do the force vs distance graphs show?

Answer 19

They show the force required to remove the mucoadhesive from the mucosal membrane at varying distances
The higher the curve, the more force is required to remove it

Question 20

List 4 specific features of mucoadhesive polymers

Answer 20

1. Hydrophilic or water-soluble polymers
2. Negatively or positively charged groups (polyelectrolytes)
3. If positive AND negative charged groups are present = poor mucoadhesion
4. Strong hydrogen bonding groups e.g. carboxyl, hydroxyl, amino-groups

Question 21

List 5 factors which influence mucoadhesion

Answer 21

1. Molecular weight of polymers
2. Concentration of mucoadhesive
3. Chain flexibility/cross-linking density of polymers
4. pH
5. Presence of non-mucoadhesive co-excipients

Question 22

List 4 solid formulations of mucoadhesives

Answer 22

1. Tablets
2. Inserts
3. Lozenges
4. Films

Question 23

List 3 semi-solid and liquid formulations of mucoadhesives

Answer 23

1. Gels and pastes
2. Viscous liquids
3. Gel-forming liquids