Mucoadhesive buccal drug delivery system

A mucoadhesive buccal drug delivery system should... 

Sustained adhesion of the dosage form (tablet, patch) to the mucosa is an important first step to successful buccal delivery. The mucus plays an important role during this mucoadhe-sive process by buccal drug delivery systems. The interaction between the mucus and mucoadhesive polymers generally used in most dosage forms can be explained by theories summarized in Table 9.1. 

Merkle, H.P. Anders, R. Wermerskirchen, A. Mucoadhesive buccal patches for peptide delivery. In Bioadhesive Drug Delivery Systems Lenaerts, V., Gurney, R., Eds. CRC Press Boca Raton, PL, 1990 105. 

Langoth N, Kahlbacher H et al (2006) Thiolated chitosans design and in vivo evaluation of a mucoadhesive buccal peptide drug delivery system. Pharm Res 23 573-579... 

Mucoadhesive drug delivery systems are comprised of administration of drug across the mucosal membrane using a mucoadhesive/bioadhesive polymer through various noninvasive routes such as peroral, ocular, buccal, nasal, stomach, intestinal, colon, vaginal, rectal, cervical or vulval. The drug delivery systems, which have made use of chitosan as a carrier for administration through various routes, have been represented in Table 2.2. 

Other modern research has highlighted the importance of CG for different drug delivery systems, as follows CG and chitosan combinations (2 3,3 2, and 4 1) as a carriers for buccal drug delivery of 10 mg propranolol hydrochloride mucoadhesive tablets coated on one face with 5% (w/v) ethyl cellulose or formulated using a direct compression technique [226] enhancement of solubility, dissolution rate and bioavailability of poorly water-soluble drug lovastatin using modified CG (by heating) and solid dispersion techniques [227] formulation and evaluation of nimesulide orodispersible tablets... 

Nafee, N.A., et al. 2004. Mucoadhesive delivery systems. I. Evaluation of mucoadhesive polymers for buccal tablet formulation. Drug Dev Ind Pharm 30 985. 

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. 

Hydroxypropyl cellulose (HPC) is a non-ionic water-soluble and pH insensitive cellulose ether. It can be used as thickening agent, tablet binder and modified release and film coating polymer. Buccal delivery formulations containing HPC and polyacrylic acid are used for many years and is used for mucoadhesive delivery systems for several drugs. 

A buccal delivery system is meant to deliver the drug from the mucosa in the oral cavity in a unidirectional fashion towards systemic circulation. A study carried out to test the mucoadhesiveness of a chitosan formulation on the buccal cells revealed that the formulation remained wedged into the buccal cells for at least one hour [121]. 

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