Method of loading beneficial agent on a prosthesis

Abstract

A beneficial agent can be loaded as discrete droplets on a prosthesis, such as a stent. Relative movement between the prosthesis and a dispensing element can be controlled to define a dispensing path in a raster format. The discrete droplets can be dispensed from a dispensing element when the dispensing element is detected to be in alignment with a cavity formed in the prosthesis such that the discrete droplets are deposited in the cavity. The discrete droplets can be dispensed from a dispensing element when the dispensing element is detected to be in alignment with a structural element of the prosthesis such that the discrete droplets are deposited on the structural element.

1 . A method for loading beneficial agent onto a prosthesis, the method comprising:
 dispensing from a dispensing element a beneficial agent in discrete droplets, each droplet having a controlled trajectory toward a prosthesis configured for implantation within a body lumen;   moving the dispensing element and the prosthesis relative to each other, the moving step performed together with the dispensing step such that a dispensing path is defined in a raster format; and   detecting whether the dispensing element is aligned or non-aligned with a structural element of the prosthesis or a cavity formed in the prosthesis.   
     
     
         2 . The method of  claim 1 , wherein the dispensing step is performed when the dispensing element is aligned with a cavity formed in the prosthesis such that at least one discrete droplet is deposited in the cavity. 
     
     
         3 . The method of  claim 1 , wherein the dispensing step is performed when the dispensing element is aligned with a structural element of the prosthesis such that at least one discrete droplet is deposited on the structural element. 
     
     
         4 . The method of  claim 1 , wherein the dispensing element and the prosthesis are separated by a distance that avoids simultaneous contact of the dispensing element and prosthesis by a discrete droplet dispensed from the dispensing element. 
     
     
         5 . The method of  claim 1 , wherein the dispensing step is performed according to instructions from a controller programmed with a portion of the prosthesis to which the beneficial agent is to be loaded. 
     
     
         6 . The method of  claim 1 , wherein the dispensing step is performed according to instructions from a controller, and the controller is not preprogrammed with a map of a portion of the prosthesis to which the beneficial agent is to be loaded. 
     
     
         7 . The method of  claim 1 , wherein the detecting step is performed with an optical device. 
     
     
         8 . The method of  claim 7 , wherein the optical device is a linear array detector. 
     
     
         9 . The method of  claim 8 , wherein the linear array detector has a resolution corresponding to the size of the discrete droplets dispensed from the dispensing element. 
     
     
         10 . The method of  claim 7 , wherein the optical device is an infrared detector. 
     
     
         11 . The method of  claim 1 , wherein the detecting step includes detecting the presence of a portion of the prosthesis that is about to move into a position in front of the dispensing element. 
     
     
         12 . The method of  claim 1 , wherein the detecting step includes detecting a shadow cast by a portion of the prosthesis. 
     
     
         13 . The method of  claim 1 , further comprising measuring an intensity of radiopaque material to determine a corresponding amount of the beneficial agent loaded on the prosthesis. 
     
     
         14 . The method of  claim 1 , further comprising detecting charge build-up on or current flow from the prosthesis to determine a corresponding amount of the beneficial agent loaded on the prosthesis 
     
     
         15 . The method of  claim 1 , wherein the prosthesis is a stent.