Statement of the Problem: Problems associated with poor bioavailability through oral route and administration difficulties through injectable routes promoted the impetus for exploring alternative routes for the delivery of such drugs. Application of dosage forms through mucosal surfaces may be able to benefit the drug molecules, which are not amenable to the oral route, such as those that undergo acid degradation or extensive first-pass metabolism.
Trans-mucosal routes of drug delivery (i.e., the mucosal linings of the nasal, rectal, vaginal, ocular, and oral cavities) offer distinct advantages over peroral administration for systemic effect.
The rationale behind the designing of muco-adhesive dosage forms include: These dosage forms readily localize in the region applied, and improve the bioavailability of drugs; Facilitate intimate contact of the formulation with the underlying absorption surface, which allows modification of tissue permeability for absorption of therapeutic moieties as well as macromolecules, such as peptides and proteins; It prolongs the residence time at the site of application and absorption to permit Controlled and Sustained drug delivery.
The targeting sites of Muco-adhesives Drug Delivery includes: Buccal Route; Sub-lingual Route; Vaginal Route;
Rectal Route; Nasal Route; Ocular Route; Gastro Intestinal Tract; May target delivery at Stomach / Intestinal
Approaches followed to incorporate drugs into the bio adhesive polymers include: Microencapsulation; Granulation by matrix formulation; Palletization techniques, etc. Techniques used for Preparation of Mucoadhesive Micro-particle include: Coacervation / Phase separation technique; Air suspension techniques (Wurster); Cross-Linking / surface polymerization; Ionotropic Gelation by using CaCl2 / Chitosan; Emulsification and Solvent Evaporation; and Spray Drying / Congealing methods; etc.