mucoadhesion

Since, the last four decades, the concept of mucoadhesion has achieved a much valuable interest in the various fields of pharmaceutics. There are many advantages of mucoadhesive buccal drug delivery system that made this a novel drug delivery system for the local as well as systemic delivery of various drugs. The main advantage of this drug delivery system is that it prolongs the residence time of the dosage form at the site of application. Due to the high blood supply and relatively high permeability of the buccal mucosa, the buccal cavity is the best option for both local as well as systemic delivery of various drugs. The main prospect of writing this review article is to present comprehensive information related to mucoadhesion and mucoadhesive drug delivery systems. The article has highlighted all the aspects of mucoadhesive drug delivery systems which will be helpful for researches and academics. The article includes detailed information about mucosa- the anatomy and physiology, the mechanisms and theories related to mucoadhesion, evaluation parameters of mucoadhesive dosage forms, mucoadhesive polymers and novel approaches related to mucoadhesive drug delivery system. Drug actions can be improved by new drug delivery system, such as mucoadhesive system. This system remains in close contact with the absorption tissue, the mucous membrane, releasing the drug at the action site leading to improvement in both local and systemic effects. The potential merits and demerits of mucoadhesive drug delivery as well as that of the polymers are also discussed. It helps enhance the bioavailability through bypassing the first-pass metabolism effect. The mucosal surface better absorption and prolong resident time. Bioadhesion can be defined as the phenomenon of interfacial molecular attractive force in midst of the surface of the biological substrate and the natural or synthetic polymers, which allows the polymers to adhere to the biological surface for an extended period of time.

In the present research work mucoadhesive microspheres of Cimetidine were prepared using Ionotropic gelation technique. All the microspheres were characterized for particle size, scanning electron microscopy, FT-IR study, DSC, percentage yield, drug entrapment, stability studies and for in vitro release kinetics and found to be within the limits. Among all the formulations M12 was selected as optimized formulation based on the physicochemical and release studies. In vitro drug release study of optimized formulation M12 showed 99.12% after 12 h in a controlled manner, which is essential for anti ulcer therapy. The innovator Cimetine conventional tablet showed the drug release of 96.15% within 1 h. The drug release of Cimetidine optimized formulation M12 followed zero order and Higuchi kinetics indicating diffusion controlled drug release.

Buccal delivery of the desired drug using mucoadhesive polymers has been the subject of interest since the early 1980s. Advantages associated with buccal drug delivery have rendered this route of administration useful for a variety of drugs. This review highlights the use of mucoadhesive polymers in buccal drug delivery the mucosa of the oral cavity presents a formidable barrier to drug penetration and one method of optimizing drug delivery is by the use of adhesive dosage forms. Mucosal adhesive materials are hydrophilic macromolecules containing numerous hydrogen-bonds –forming groups. They have been called “wet” adhesives in that they require moisture to become adhesive and this may be supplied by the saliva: the latter may also acts as the dissolution medium. Various buccal-adhesive formulations have been investigated with a view to delivering drugs locally or systematically. We focus on the new generation of mucoadhesive polymers such as thiolated polymers, followed by the recent mucoadhesive formulations for buccal drug delivery.

Bioadhesion can be defined as the process by which a natural or a synthetic polymer can adhere to a biological substrate. When the biological substrate is a mucosal layer then the phenomena is known as mucoadhesion. The substrate possessing bioadhesive property can help in devising a delivery system capable of delivering a bioactive agent for a prolonged period of time at a specific delivery site. The current review  provides  a good insight on mucoadhesive polymers, the phenomenon of mucoadhesion and the factors which have the ability to affect the mucoadhesive properties of a polymer. This review also considers the basic mechanisms by which mucoadhesive can adhere to a mucous membrane  in terms of the nature of the adhering surfaces and the forces that may be generated to secure them together. Mucosal adhesion is backed by several theories which include electronic, adsorption, wetting, diffusion, fracture and mechanical. Stages of mucoadhesion include contact stage and consolidation stage.

Buccal administration of drug provides a convenient route of administration for both systemic and local drug actions. The preferred site for retentive oral transmucosal delivery systems and for sustained and controlled release delivery device is the buccal mucosa. Rapid developments in the field of molecular biology and gene technology resulted in generation of many macromolecular drugs including peptides, proteins, polysaccharides and nucleic acids in great number possessing superior pharmacological efficacy with site specificity and devoid of untoward and toxic effects. However, the main impediment for the oral delivery of such drugs as potential therapeutic agents is their extensive presystemic metabolism, instability in acidic environment resulting into inadequate and erratic oral absorption. Direct access to the systemic circulation through the internal jugular vein bypasses drug from the hepatic first pass metabolism leading to high bioavailability. The objective of this article is to review the developments in buccal adhesive drug delivery system as patches.