Polymers: Mucoadhesive Dosage Forms Flashcards Preview

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Flashcards in Polymers: Mucoadhesive Dosage Forms Deck (23)
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Define: Muscoadhesion

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


List 3 advantages of mucoadhesive delivery
i.e. using a polymer to adhere to mucosal membranes

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


Describe the structure of mucosal membranes

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


Describe the structure of the mucins found on the mucosal membrnes

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


Define: Mucin

Principle component of mucous
Mucopolysaccharide or glycoprotein


List 4 functions of mucosal membranes

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


Describe the characteristics of mucosal surfaces

- 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


How is mucous constantly moved on?

Ciliary cells beat in a formulated fashion
Clears mucous into stomach to be digested


List the 4 theories of mucoadhesion

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


Describe the electronic theory of mucoadhesion

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


Describe the absorption theory of mucoadhesion

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


Describe the diffusion theory of mucoadhesion

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


Describe the wetting theory of mucoadhesion

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


List the stages of mucosal adhesion

1. Contact stage = contact, swelling and wetting
2. Consolidation stage = non-covalent bonds formation, diffusion and inter-penetration


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

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


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

Tissues are not always fresh


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

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


What occurs in the flow cell method?

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


What do the force vs distance graphs show?

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


List 4 specific features of mucoadhesive polymers

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


List 5 factors which influence mucoadhesion

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


List 4 solid formulations of mucoadhesives

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


List 3 semi-solid and liquid formulations of mucoadhesives

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