bioactive agents are delivered to a body site in need of the same by providing a first aliquot portion of a reaction mixture which includes an aldehydic polymer solution , and a second aliquot portion of a reaction which includes a cross - linking hydrazide and a bioactive agent . the first and second aliquot portions may be mixed to form the reaction mixture thereof . the thus formed reaction mixture may then be installed at the body site whereby the reaction mixture is allowed to solidify in situ within about 1 to 10 minutes into a reaction product comprised of a hydrazide cross - linked oxidized aldehydic polymer matrix with the bioactive agent entrapped therein .