A catheter system includes a catheter having a proximal end, a distal end, and a lumen extending therein. An administering portion is disposed at the distal end of the catheter and is configured to administer a bolus of liquid in response to positive pressure in a distal portion of the lumen. The catheter system of the present invention has a dead space of less 0.32 cc and preferably less than 0.15 cc in which residual therapeutic agents remain after delivery. The present invention also includes a method of administering a liquid to a treatment site. The distal end of the catheter is transluminally positioned proximate the treatment site. The catheter is charged by placing a bolus of the liquid in the lumen. A positive pressure is created to drive the bolus to the administering tip to express the bolus from the distal end of the catheter.