Microspheres bioadhesive

Santos et al. [112] correlated these two methods and concluded that each method could be used alone as the relevant indicator of microsphere bioadhesion. 

Ramdas, M., Dileep, K.J., Anitha, Y., Paul, W., and Sharma, C.P., Alginate encapsulated bioadhesion chitosan microspheres for intestinal drug delivery, J. Biomater. Appl, 13 290-296 (1999). 

Chickering, D.E.lll, and Mathiowitz, E., Bioadhesive microspheres. 1. A novel electrobalance-based method to study adhesive interactions between individual microspheres and intestinal mucosa, J. Control. Rel., 34 251-262 (1995). 

Ilium, L., Jorgensen, H., Bisgaard, H., Krogsgaard, O., and Rossing, N., Bioadhesive microspheres as a potential nasal drug delivery system, Int. J. Pharm., 39 189-199 (1987). 

Umamaheshwari, R.B., et al. 2002. Floating-bioadhesive microspheres containing acetohydroxamic acid for clearance of Helicobacter pylori. Drug Deliv 9 223. 

Bioadhesive formulations and microsphere delivery systems in particular have attracted much attention. As drug formulations are usually rapidly removed from the site of deposition by the mucociliary clearance, increasing the retention time of drug in the nasal cavity via bioadhesion can increase bioavailability [28], Bioadhesion may be defined as the ability of a material (synthetic or biological) to adhere to a biological tissue for an extended period of time. When applied to a mucous membrane, a bioadhesive polymer may adhere primarily to the mucus layer or epithelial cell surface in a phenomenon known as mucoadhesion [29,30]. The bioadhesive properties of a wide range of materials have been evaluated over the last decade. 

Ilium, L., et al. 2001. Bioadhesive starch microspheres and absorption enhancing agents act synergistically to enhance the nasal absorption of polypeptides. Int J Pharm 222 109. 

OHagan, D.T., D. Rafferty, S. Wharton, and L. Ilium. 1993. Intravaginal immunization in sheep using a bioadhesive microsphere antigen delivery system. Vaccine 11 660. 

Microparticulate systems present the advantage, in comparison with single-unit solid systems, to guarantee a wider contact area between the drug and the mucosa. Different microparticulate systems intended for vaginal administration were developed they include liposomes, microcapsules, and microspheres. Such systems can possess intrinsic bioadhesive properties or can be loaded in a vehicle with bioadhesive properties. 

Jacob, J., Santos, C., Carino, G., et al. An in-vitro bioassay for quantification of bioadhesion of polymer microspheres to mucosal epithelium. Proceed. Int. Symp. Control. Rel. Bioact. Mater. 22 312—313, 1995. 

Microspheres prepared with bioadhesive polymers have some additional advantages they assure much more intimate and prolonged contact with the mucous layer and improved drug absorption due to additional delay in mucociliary clearance. Bioadhesive microspheres can significantly improve patient compliance as all the advantages described lead to reduction in the frequency of drug administration [3,74]. 

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