Stent

Abstract

A stent capable of stably loading a biologically/physiologically active substance, without causing its decomposition or deterioration, and permitting it to release itself slowly over a long period of time without being rapidly released in a short period, after being implanted in a lesion. The stent ( 1 ) comprises a cylindrical stent main body ( 2 ) having an opening on each end and extending in axial direction between the two openings, and a sustained release coating formed on the surface of said stent main body from which a biologically/physiologically active substance is released, and wherein said sustained release coating is composed of a layer of a biologically/physiologically active substance ( 3 ) which covers the surface of said stent main body, and a polymer layer ( 4 ) which covers said layer of a biologically/physiologically active substance ( 3 ) on said layer of a biologically/physiologically active substance ( 3 ), and said layer of a biologically/physiologically active substance ( 3 ) contains at least one kind of fat-soluble biologically/physiologically active substance, and said polymer layer ( 4 ) contains a polymer miscible with said biologically/physiologically active substance and fine particles ( 5 ) equal to or smaller than 5 μm in particle diameter dispersed in the polymer.

What is claimed is:  
     
         1 . A stent to be implanted in a duct of a living body, comprising: 
 a cylindrical stent main body having an opening on each end and extending in axial direction between the two openings and    a sustained release coating formed on the surface of said stent main body from which a biologically/physiologically active substance is released; wherein    said sustained release coating composed of: 
 a layer of a biologically/physiologically active substance which covers the surface of said stent main body; and  
 a polymer layer which covers said layer of a biologically/physiologically active substance on said layer of a biologically/physiologically active substance,  
 said layer of a biologically/physiologically active substance containing at least one kind of fat-soluble biologically/physiologically active substance,  
 said polymer layer containing a polymer miscible with said biologically/physiologically active substance and fine particles equal to or smaller than 5 μm in particle diameter dispersed in the polymer.  
   
     
     
         2 . The stent as defined in  claim 1 , wherein the stent main body is formed from a metallic material.  
     
     
         3 . The stent as defined in  claim 1 , wherein the stent main body is formed from a polymeric material.  
     
     
         4 . The stent as defined in any of  claims 1  to  3 , wherein the layer of a biologically/physiologically active substance is composed solely of a biologically/physiologically active substance.  
     
     
         5 . The stent as defined in any of  claims 1  to  4 , wherein the biologically/physiologically active substance is any of antineoplastic agent, immunosuppressor, antibiotic, antirheumatic, antilipemic agent, ACE inhibitor, calcium antagonist, antiallergic agent, retinoid, antioxidant, and anti-inflammatory agent.  
     
     
         6 . The stent as defined in any of  claims 1  to  5 , wherein the biologically/physiologically active substance is one which has a molecular weight not higher than 600.  
     
     
         7 . The stent as defined in any of  claims 1  to  6 , wherein the polymer is a silicone polymer.  
     
     
         8 . The stent as defined in any of  claims 1  to  7 , wherein the fine particles are those of a low-molecular-weight water-soluble salt having a molecular weight not higher than 1000.  
     
     
         9 . The stent as defined in  claim 8 , wherein the low-molecular-weight salt is sodium chloride.  
     
     
         10 . The stent as defined in any of  claims 1  to  7 , wherein the fine particles are those of a water-insoluble substance.  
     
     
         11 . The stent as defined in  claim 10 , wherein the water-insoluble substance is a silica filler.  
     
     
         12 . The stent as defined in  claim 10 , wherein the water-insoluble substance is polytetrafluoroethylene.