Mucoadhesive propertie

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. 

Polyanhydrides based on unsaturated and fatty acid-derived monomers are shown in Table III. Poly(fumaric acid) (PFA) was fist synthesized by Domb et al. (1991) by both melt polycondensation and solution polymerization. The copolymer of fumaric acid and sebacic acid (P(FA-SA)) has been synthesized and characterized (Domb et al., 1991 Mathiowitz et al., 1990b). The mucoadhesive properties of this polymer... 

The mucoadhesive properties of several classes of hydrogels have been identified, and two types of polymers have attracted special attention. Polyacrylates and their cross-linked modifications represent the anionic type, chitosan and its derivatives the cationic group. In addition, both types of polymers show a number of interesting characteristics beneficial for the administration of a wide range of therapeutics. 

In recent studies both in vitro (Caco-2 cells) and in vivo in rats, TMC with a degree of trimethylation of 60% was proven to be an excellent intestinal absorption enhancer of the peptide drugs buserelin and octreotide. The observed absolute bioavailability values were 13 and 16% for buserelin and octreotide, respectively [83] (impublished data Fig. 5). Permeation enhancing effects were more responsible for these increased bioavailabilities, rather than the mucoadhesive properties of the TMC polymers. Nevertheless, mucoadhesion is a prerequisite for these polymers in order to further act as absorption enhancers. 

Lehr, C.M., et al. n vitro evaluation of mucoadhesive properties of chitosan and some other natural polymers,Int. J. Pharm., 78, 43, 1992. 

Chitosan not only displays mucoadhesive properties, but also acts as an absorption enhancer in the intestinal cell layer membrane [34,35]. The mucoadhesion raises the concentration of... 

As demonstrated in a number of studies, the inhibitory activity of mucoadhesive polymers can be extensively improved by the immobilization of enzyme inhibitors onto the polymer without markedly influencing the mucoadhesive properties of the polymer. Such conjugates, comprising a mucoadhesive polymer and a covalently bound enzyme inhibitor exhibit diverse... 

Langoth et al. [86] studied the properties of matrix-based tablets containing the novel pentapeptide leu-enkephalin (Tyr-Gly-Gly-Phe-Leu) that has been shown to have pain-modulating properties. The matrix-based tablets were made with the thiolated polymer PCP. The covalent attachment of cysteine to the anionic polymer PCP leads to an improvement of the stability of matrix tablets, enhances the mucoadhesive properties, and increases the inhibitory potency of PCP towards buccal enzymes. All these factors lead to stability of the peptide and a controlled drug release for the peptide was obtained for more than 24 h. Also, the tablets based on thiolated PCP remained attached on freshly excised porcine mucosa 1.8 times longer than the corresponding unmodified polymer. 

A study compared the buccal mucoadhesive properties for different polymeric films that differed in their cross-linking status [91]. Synthetic (Carbopol 971P, PCP), semisynthetic (SCMS), and natural carrageenan (X-type) were analyzed for their mucoadhesive properties using a TA-XT2i texture analyzer. 

Ferrari, F., et al. 1997. Technological induction of mucoadhesive properties on waxy starches by grinding. Eur J Pharm Sci 5 277. 

Using a new approach that involves the utilization of the mucoadhesive property of polymers to improve the ocular absorption of poorly absorbed drugs. 

Some of the most promising data on gastroretentive delivery systems using bioadhesion have resulted from the use of acrylate-based as well as chitosan-based polymers. Poly(acrylates) have been shown to have significant mucoadhesive properties in contact with intestinal mucosal tissues.104 122 135 Longer et al.136 demonstrated successful reduction in the... 

Microspheres (10 to 200 pm in diameter) of poly(fumaric acid—cose-bacic acid) anhydride (20 80) [P(FA SA)] were shown to exhibit very strong and pronounced mucoadhesive properties both in vitro and in vivo.143 145 The microspheres were tested for their effect on GI transit of low-molecular-weight drugs salicylic acid and dicumarol. As compared with the control (drug-loaded alginate microspheres of similar size), the P(FA SA) microspheres significantly delayed the GI transit of these drugs in rats.145... 

Takeuchi, H., Matsui, Y., Yamamoto, H., and Kawashima, Y. Mucoadhesive properties of carbopol or chitosan-coated liposomes and their effectiveness in the oral administration of calcitonin to rats. J. Contr. Rel. 86 235—242, 2003. 

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