Types of buccal dosage forms & Mechanisms of Buccal Absorption

Types of buccal dosage forms

1. Buccal Mucoadhesive Tablets:

Concept:

• These are tablets designed to adhere to the buccal mucosa and release the drug over an extended period.

Components:

1. Mucoadhesive polymers: Such as hydroxypropyl methylcellulose (HPMC), chitosan, and carbopol. They ensure prolonged adhesion of the tablet to the mucosal surface.

2. Permeation enhancers: Agents like fatty acids and surfactants improve the drug's penetration through the mucosal barrier.

Advantages:

• Prolonged drug release, improved bioavailability, reduced dosing frequency, and potentially enhanced patient compliance.

Challenges:

• Ensuring a comfortable size and shape, maintaining adhesion in the wet environment of the mouth, and achieving desired release kinetics.
  

2. Buccal Patches and Films:

Concept:

• Thin, flexible patches or films that adhere to the buccal mucosa.

Components:

1. Polymeric matrix: Examples include polyvinyl alcohol, polyethylene oxide, and pullulan. This forms the base of the film or patch.

2. Plasticizers: Such as glycerol or propylene glycol, which provide flexibility.

Advantages:

• More comfortable than tablets, potentially faster onset of action, discrete, and more uniform drug distribution.

Challenges:

• Ensuring uniformity in drug content, achieving adequate mucoadhesion, and preventing rapid drug release.
  

3. Semisolids (Ointments and Gels) and Powders:

Concept:

• Semisolids and powders applied to the buccal mucosa, which then release the drug.

Components for Semisolids:

1. Gelling agents: Used in the formulation of gels, like carbomers or cellulose derivatives.

2. Base: In ointments, a hydrophobic (oleaginous) or hydrophilic base is used.

Components for Powders:

• Usually, these are micronized or nanosized drug particles that may be mixed with excipients to improve dispersion in the oral cavity.

Advantages:

• Simple to formulate, potentially faster onset of action, and versatile (can accommodate various drugs).

Challenges:

• Ensuring uniform drug distribution, preventing rapid drug release, and maintaining the formulation in the site of application due to saliva washout.
  

Mechanisms of Buccal Absorption

1. Passive Diffusion:

• Majority of drugs are absorbed through this mechanism. It is driven by the concentration gradient of the drug across the buccal mucosa.

2. Carrier-Mediated Transport:

• Involves drug molecules being carried across the mucosa via specific transport proteins.

3. Endocytosis:

• The cell membrane engulfs the drug molecules, leading to their internalization.

Here is the diagram illustrating the "Types and Mechanisms of Buccal Dosage Forms":