in accordance with the present invention , there are provided polymeric drug delivery systems in which the drug is bound to a water - soluble polymer to provide a form of soluble drug delivery especially for those cases in which the drug by itself is water - insoluble . in particular , the drug taxol is covalently bound to water - soluble polyethylene glycols such as linear polyethylene glycols , branched polyethylene glycols , star polyethylene glycols , and branched copolymers of polyethylene glycols with other functional monomers to comprise a form of polymeric drug delivery . also , crosslinked insoluble gels of these materials are prepared to serve as a form of implantable drug delivery .