MUCOADHESIVE POLYMERS FOR NASAL AND BUCCAL DRUG DELIVERY

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The development of nasal and buccal controlled release systems is examined with special emphasis on the chemical and physical properties of the potentially mucoadhesive polymeric carriers. New copolymeric formulations were synthesized, containing carboxylic, hydroxylic or ionic groups which can interact with mucin solutions, mucin gels or mucosa to provide a relatively permanent mucoadhesive bond. These formulations could be prepared either in the form of microparticles or in the form of thin microdiscs. They were swellable in water or various buffered solutions. The polymers used in the formulations were characterized with surface analysis, measurement of their degree of ionization and analysis of the crosslinked properties and degree of swelling. Two novel experi- mental techniques are used to characterize the mucoadhesive bond strength. For muco-adhesive microparticles both in nasal and buccal applications, a flow channel is used containing a mucin gel or nasal mucus or sublingual tissue with mucus. The particle detachment from the mucus surface is studied as a function of flow conditions of the fluid (gas) passing over this surface. For microdiscs, a tensile testing process is used whereby the candidate bioadhesive is brought in contact with mucus for a known period of time and is further detached by application of force.