An implantable drug delivery system including: a biocompatible or bio-inert housing containing a drug infusion pump, a drug chamber from which a liquid drug is dispensed when the pump applies a force to the drug chamber, and an internal controller actuating the pump a delivery catheter extending from the housing to one or more drug delivery treatment sites in a target tissue, wherein the catheter includes a lumen having an inlet to receive a drug pumped from the drug chamber and an outlet are positioned at the target tissue, wherein the drug flows through the outlet to the target tissue, and wherein the internal controller stores and executes an automatic periodic flow regimen which commands the pump and drug chamber to periodically dispense an intermittent bolus or pulse of the liquid drug, wherein the periodic flow regimen provides a prophylactic treatment for granuloma.
