PERIOPERATIVE PHARMACOKINETICS OF TRANSDERMAL FENTANYL IN ELDERLY ANDYOUNG-ADULT PATIENTS

The perioperative pharmacokinetics of transdermally-delivered fentanyl were compared in 10 young adult (mean [range] age 32.7, [25-38] yr) a nd eight elderly (mean [range] age 73.7 [64-82] yr) patients following abdominal surgery. Transdermal fentanyl patches designed to release 5 0 mu g h(-1) were applied 2 h preoperatively and left in place for 72 h. Plasma fentanyl concentrations were measured by radioimmunoassay du ring patch application and for 30 h after patch removal. The mean half -time (time for plasma concentrations to double after patch applicatio n) was 4.2 h in the younger group and 11.1 h in the elderly group (P<0 .005). Mean maximum plasma concentrations were 1.9 ng ml(-1) and 1.5 n g ml(-1) in the younger and elderly groups respectively (ns). There we re no differences in the time at which maximum plasma concentrations o ccurred (t(max)), elimination half-life after patch removal, or AUC((0 -infinity)).