A hydrogel forming system which comprises a hydrophobic macromer with unsaturated
group terminated ends and a hydrophilic polymer which is a polysaccharide containing
hydroxy groups which are reacted with unsaturated group introducing compound, is
convertible by free radical polymerization to form a hydrogel containing a three
dimensional crosslinked polymer network containing hydrophobic and hydrophilic
components. Agent can be entrapped in the polymer network, e.g., drugs, macromolecules
or synthetic or natural polymers, for controlled release therefrom. In one embodiment,
a vascular stent is coated with hydrogel with therapeutic agent entrapped therein.
