Agent delivery catheter

A catheter, comprising:

• a tube comprising a proximal end, a distal end, and a lumen, the lumen being sealed at the distal end;
• a retractable stylet carried in the lumen, wherein the retractable stylet is adapted to stiffen the tube during a placement process and is movable relative to the tube, wherein the lumen being sealed at the distal end prevents the retractable stylet from protruding from the distal end of the tube;
• a coupler connected to the distal end of the tube;
• and
• a capillary tube carried in the lumen, the capillary tube comprising a distal tip for releasing an agent at the distal tip to a biological tissue, wherein the distal tip of the capillary tube is an exposed portion of the capillary tube that protrudes beyond the distal end of the tube and a distal end of the coupler.

A convection-enhanced delivery (CED) method, comprising:

• placing a distal tip of a catheter at a target location in the brain, the catheter comprising:
• a multi-lumen tube comprising a proximal end, a distal end, a first lumen, and a second lumen that is independent of the first lumen, the first lumen being sealed at the distal end;
• a retractable stylet carried in the first lumen of the multi-lumen tube, wherein the stylet is adapted to stiffen the multi-lumen tube during a placement process and is movable relative to the multi-lumen tube, wherein the first lumen being sealed at the distal end prevents the retractable stylet from protruding from the distal end of the multi-lumen tube;
• and
• a capillary tube of the second lumen of the multi-lumen tube, the capillary tube comprising the distal tip for releasing an agent at the distal tip to a biological tissue, wherein the distal tip of the capillary tube is an exposed portion of the capillary tube that protrudes beyond the distal end of the multi-lumen tube,
• removing the retractable stylet at least partially from the first lumen to impart flexibility to the catheter;
• and
• delivering an agent through the capillary tube to the target location.