Title:  Cross-linked polysaccharide drug carrier

United States Patent:  6,303,585

Assignee:  Orquest, Inc. (Mountain View, CA)

Filed:  July 1, 1998

A carrier and a method for preparing it are provided for use in the delivery of therapeutic agents. A polysaccharide is reacted with an oxidizing agent to open sugar rings on the polysaccharide to form aldehyde groups. The aldehyde groups are reacted to form covalent oxime linkages with a second polysaccharide and each of the first and second polysaccharide is selected from the group consisting of hyaluronic acid, dextran, dextran sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, heparan, heparan sulfate and alginate.

SUMMARY OF THE INVENTION

The present invention provides biodegradable carriers for the delivery of therapeutic agents, methods of making the carriers and methods of using the carriers.

A biodegradable carrier of the present invention comprises a cross-linked first and second polysaccharide, wherein each of the first and the second polysaccharide is a derivative of a member selected from the group consisting of hyaluronic acid, dextran, dextran sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, heparin, heparan sulfate and alginate. The first polysaccharide contains aldehyde groups derived from oxidized sugar rings. The second polysaccharide an amine derivative and the first and second polysaccharides are covalently cross-linked through these groups which forms imine linkages. In the present invention, the cross-linking reaction proceeds without utilizing extraneous cross-linking or ionic binding agents.

The method of making the biodegradable carriers comprises the steps of oxidizing a first polysaccharide to form a first polysaccharide derivative having aldehyde groups, and reacting the first polysaccharide derivative with a second polysaccharide amine derivative under conditions such that the aldehyde groups covalently react with the amine sites to form a cross linked carrier.

The present invention also provides methods of using the carrier to deliver therapeutic agents by administering the carrier at the sites of desired therapeutic intervention.

The ratios of the first and second polysaccharide can be varied to change both the physical and biological properties of the carrier. For example, a higher ratio of aldehyde bearing polysaccharide would be preferred for immobilizing a therapeutic agent to the carrier. The presence of unreacted but active aldehydes provides sites for covalent linkage to a therapeutic agent.

A carrier of the present invention can be produced in a variety of physical forms. For example, it can be made into a gel-like form for injection or a sponge-like form for implantation at a desired site of therapeutic intervention.

A carrier of the present invention provides the advantage of being biocompatible while maintaining a prolonged biodegradation rate due to the cross-linking; providing controlled release of the therapeutic agent and having the flexibility of formulation in gel-like or sponge-like form to accommodate desired therapeutic intervention.

As used herein therapeutic agent means any bioactive agent, such as a protein, polypeptide, or amino acid, including growth factors, growth factor receptors, cytokines, hormones, antibodies or chemical agents, such as, for example, non-peptide hormones chemical mimetics of growth factors and receptors that have been shown to have a biological effect.

Claim 1 of 30 Claims

What is claimed is:

1. An injectable biodegradable carrier for the delivery of therapeutic agents, said carrier comprising

a first polysaccharide cross-linked to a second polysaccharide, wherein said first and second polysaccharides is each a member selected from the group consisting of hyaluronic acid, dextran, dextran sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate, heparin, heparan sulfate and alginate;

and wherein said first and second polysaccharides are covalently cross-linked to each other through imine bonds between amino groups on said second polysaccharide and aldehyde groups from oxidized sugar rings on said first polysaccharide.

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