Body cavity drug delivery with thermo-irreversible polyoxyalkylene and ionic polysaccharide gels

Abstract

Balanced pH, thermo-irreversible gels are ideal vehicles for drug delivery to a body cavity of a mammal. The gels contain a mixture of a polyoxyalkylene block copolymer or polyether together with an ionic polysaccharide which is thermo-irreversibly gelled in the presence of a counter-ion.

That which is claimed:  
     
         1 . A method of forming a gel material in situ in contact with at least one biological tissue, in a body cavity, comprising: 
 preparing a material which comprises an ionic polysaccharide and a polymer, said polymer having polyoxyalkylene blocks comprising a block copolymer of the general formula:    Y[(A) n - - - E - - - H] x      where A is a polyoxyalkylene moiety having an oxygen/carbon atom ratio of less than 0.5, x is at least 2, Y is derived from water or an organic compound containing x reactive hydrogen atoms, E is a polyoxyethylene moiety constituting at least 60 percent by weight of the polyoxyalkylene block copolymer, n has a value such that the minimum molecular weight of A is between about 500 and about 900, as determined by the hydroxyl number of an intermediate of general formula:    Y[(A) n - - - H] x      and the average molecular weight of the polyoxyalkylene block copolymer is between about 5000 and about 50,000; placing said material in contact with at least one biological tissue; and cross-linking said material in contact with said at least one biological tissue via, said cross-linking being mediated through a thermal mechanism, a counter-ion mechanism or a combination thereof wherein the cross-linking of said material results in an in situ formation of the gel material.