A method is provided for administering an active drug agent to cells adhering and/or adjacent to a substrate, said substrate comprising one or more immobilized enzymes, which are capable of converting an inert prodrug into an active drug agent, said method comprising providing at least one inactive prodrug to said substrate. Also a kit is provided which comprise a substrate comprising one or more immobilized enzymes capable of converting an inert prodrug into an active drug agent, and at least one inert prodrug. A stent is also provided, which comprise a substrate comprising one or more immobilized enzymes capable of converting an inert prodrug into an active drug agent.