United States Patent:  5,955,096

Assignee:  Brown University Research Foundation (Providence, RI)

Filed:   June 25, 1996

Methods and compositions are provided for enhancing the bioadhesive properties of polymers used in drug delivery systems. The bioadhesive properties of a polymer are enhanced by incorporating an anhydride oligomer into the polymer to enhance the ability of the polymer to adhere to a tissue surface such as a mucosal membrane. Anhydride oligomers which enhance the bioadhesive properties of a polymer include oligomers synthesized from dicarboxylic acid monomers, preferably those found in Krebs glycolysis cycle, especially fumaric acid. The oligomers can be incorporated within a wide range of polymers including proteins, polysaccharides and synthetic biocompatible polymers. In one embodiment, anhydride oligomers can be incorporated within polymers used to form or coat drug delivery systems, such as microspheres, which contain a drug or diagnostic agent. The oligomers can either be solubilized and blended with the polymer before manufacture or else used as a coating with polymers over existing systems. The polymers, for example in the form of microspheres, have improved ability to adhere to mucosal membranes, and thus can be used to deliver a drug or diagnostic agent via any of a range of mucosal membrane surfaces including those of the gastrointestinal, respiratory, excretory and reproductive tracts.

Summary of the Invention

Polymers with enhanced bioadhesive properties are provided wherein anhydride monomers or oligomers are incorporated into the polymer. The polymers may be used to form drug delivery systems which have improved ability to adhere to tissue surfaces, such as mucosal membranes. The anhydride oligomers are formed from organic diacid monomers, preferably the diacids normally found in the Krebs glycolysis cycle. Anhydride oligomers which enhance the bioadhesive properties of a polymer have a molecular weight of about 5000 or less, typically between about 100 and 5000 daltons, or include 20 or fewer diacid units linked by anhydride linkages and terminating in an anhydride linkage with a carboxylic acid monomer.

The oligomer excipients can be blended or incorporated into a wide range of hydrophilic and hydrophobic polymers including proteins, polysaccharides and synthetic biocompatible polymers. In one embodiment, oligomers can be incorporated within polymers used to form or coat drug delivery systems, such as microspheres, which contain a drug or diagnostic agent. In another embodiment, oligomers with suitable molecular weight may be used alone to encapsulate therapeutic or diagnostic agents. In yet another embodiment, anhydride oligomers may be combined with metal oxide particles to improve bioadhesion even more than with the organic additives alone. Organic dyes because of their electronic charge and hydrophobicity/hydrophilicity can either increase or decrease the bioadhesive properties of polymers when incorporated into the polymers.

The polymers, for example in the form of microspheres, have increased ability to adhere to mucosal membranes, and thus can be used to deliver a drug or diagnostic agent via any of a range of mucosal membrane surfaces including those of the gastrointestinal, respiratory, excretory and reproductive tracts.

Claim 1 of 32 Claims

1. A method for improving the bioadhesiveness of a polymer, the method comprising incorporating an anhydride oligomer in the polymer in an amount effective to enhance the ability of the polymer to adhere to a mucosal membrane, wherein the anhydride oligomer includes twenty or fewer diacid units linked by anhydride linkages or has a molecular weight of 5000 Daltons or less, and wherein the anhydride oligomer is incorporated by dispersing solid particles of anhydride oligomer into the polymer, dissolving anhydride oligomer and polymer in a solvent for both the polymer and the oligomer, or blending liquified anhydride oligomer with liquified polymer.

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