Definition of Mucosal Drug Delivery
Mucosal drug delivery administers drugs through mucosal surfaces (e.g., oral, nasal, rectal, vaginal, ocular), offering advantages like localized effects, bypassing liver metabolism, and improved bioavailability.
Key Mucosal Sites
Oral Mucosa:
Includes buccal and sublingual areas; sublingual is highly permeable with a protective mucus layer.
Nasal Mucosa:
Vascularized for rapid drug action; contains ciliated cells for mucus clearance.
Rectal Mucosa:
Allows systemic delivery while bypassing some liver metabolism.
Vaginal Mucosa:
Stratified epithelium affected by hormones, suitable for local/systemic delivery.
Ocular Mucosa:
Thin layer on the eye surface for topical drug delivery.
Transport Mechanisms
Passive Diffusion: High to low concentration, common for lipophilic drugs.
Facilitated Diffusion: Carrier proteins move drugs passively.
Active Transport: Carrier proteins move drugs against gradients, requiring energy.
Endocytosis: Cell membrane engulfs drugs into vesicles.
Retention Strategies
Matrix System: Drug in a polymer matrix released as it erodes (e.g., buccal tablets).
Reservoir System: Encapsulated drug diffuses through a membrane at a controlled rate.
Swelling-Controlled Release: Polymer swells on contact with mucosa, releasing the drug gradually.