Mucoadhesive delivery device

Stimulation of saliva production is under sympathetic and parasympathetic control. Parasympathetic stimulation produces a serous watery secretion, whereas sympathetic stimulation produces much thicker saliva. Drug delivery systems, therefore, should not be placed over a duct or adjacent to a salivary duct, as this may dislodge the retentive system or may result in excessive wash-out of the drug or rapid dissolution/erosion of the delivery system making it difficult to achieve high local drug concentrations. If a retentive system is placed over salivary ducts, the reduced salivary flow rate may produce less or no mucus which is required for the proper attachment of a mucoadhesive delivery device. 

Another hydrophilic polymer that has received attention is poly(vinyl alcohol) (PVA). This material holds tremendous promise as a biological drug delivery device because it is nontoxic, hydrophilic and exhibits good mucoadhesive properties (Peppas, 1987). In one of the first applications of this material, Langer and Folkman (1976) investigated the use of copolymers of PHEMA (Hydron ) and PVA as delivery vehicles for polypeptide drugs. 

Remunan-Lopez, C., Portero, A., VilaJato, J.L., and Alonso, M.J., Design and evaluation of chitosan/ethylcellulose mucoadhesive bilayered devices for buccal drug delivery, J. Control. Rel., 55 143-152 (1998). 

Delivery device Mucolytic agents Enzyme inhibitors Mucoadhesives... 

The term mucoadhesion is commonly used to describe an interaction between the mucin layer, which lines the entire GI tract, and a bioadhesive polymer, which could be natural or synthetic in origin.From the oral delivery standpoint, these systems are used to immobilize and localize a drug delivery device in the selected regions of the GI tract, which could be an oral cavity (buccal and sublingual routes), the esophagus, stomach, small intestine, or colon (oral route). For the most part, research in this area has focused on the design of polymeric micro- and nanoparticulate systems that use hydrophilic polymers, primarily due to their propensity to interact with the mucosal surface. ... 

The size of the delivery system varies with the type of formulation, i.e., a buccal tablet may be approximately 5-8 mm in diameter, whereas a flexible buccal patch may be as large as 10-15 cm in area. Mucoadhesive buccal patches with a surface area of 1-3 cm are most acceptable. It has been estimated that the total amount of drug that can be delivered across the buccal mucosa from a 2-cm system in 1 day is approximately 10-20 mg.f The shape of the delivery system may also vary, although for buccal drug administration, an ellipsoid shape appears to be most acceptable. The thickness of the delivery device is usually restricted to only a few millimeters. The location of the delivery device also needs to be considered. A mucoadhesive retentive system is preferred over a conventional dosage form. A bioadhesive buccal patch would appear to be the most appropriate delivery system because of its flexibility and the area of the buccal mucosa available for its application. The maximal duration of buccal drug retention and absorption is approximately 4-6 h because food and/or liquid intake may require removal of the delivery device. 

In the gastrointestinal tract, a mucoadhesive drug delivery system provides advantages in prolonging the residence time of devices. The use of pH-sensitive bioadhesive polymers has been proposed [26], An extensive review of pH-sensi-tive hydrogels is given by Brpndsted and Kopecek [27],... 

Nair, M.K., and Chien, Y.W., Development of anticandidal delivery systems. 2. Mucoadhesive devices for prolonged drug delivery in the oral cavity. Drug Dev. Ind. Pharm., 22 243-253 (1996). 

The total biomedical PEG literature includes thousands of papers and hundreds of applications. Some of the applications, in addition to those mentioned above, include dmg delivery depots, cell encapsulants, lubricious surfaces, mucoadhesive dmg carriers, coatings for miaofluidic devices, antibacterial coatings, nonthrombogenic coatings, control of cell fusion, applications in ophthalmic implants, and separation membranes. 

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