BACKGROUND: Subcutaneous tissue is an important target for drug deposition or infusion. A local trauma may induce alterations in local microcirculation and diffusion barriers with consequences for drug bioavailability. We examined the influence of infusion catheters' wear time on local microcirculation and infusion counter pressure. METHODS: One steel catheter and one Teflon (Dupont, Wilmington, DE) catheter were inserted in subcutaneous, abdominal adipose tissue (SCAAT) in 10 healthy, lean men. The catheters were infused with isotonic saline at a rate of 10 microL/h for 48 h. Another steel catheter and a Teflon catheter were inserted contralateral to the previous catheters after 48 h. The infusion counter pressure was measured during a basal infusion rate followed by a bolus infusion. The measurements during a basal rate infusion were repeated after the bolus infusion. Adipose tissue blood flow (ATBF) was measured in SCAAT continuously. RESULTS: A significant increase in ATBF was observed with wear time for Teflon but not for steel catheters. Mean infusion pressure during the bolus phase increased significantly from 0 to 48 h for Teflon but not for steel catheters. ATBF and infusion counter pressure was similar between Teflon and steel catheters after acute catheter implantation and after wear time of 48 h. The maximum value of pressure during the bolus phase increased with wear time of a catheter. CONCLUSIONS: ATBF and bolus mean infusion pressure increased significantly with a wear time of 48 h in Teflon but not in steel catheters. The maximal pressure required to deliver a bolus infusion increased with wear time of a catheter. A higher maximal pressure was required to deliver a bolus infusion through a Teflon than through a steel catheter. We propose that the difference in infusion counter pressure and ATBF between Teflon and steel catheters with wear time may be explained by better biocompatibility of steel than Teflon.