Transdermal fentanyl disposition in elderly subjects

The pharmacokinetic characteristics of a 20-cm2 fentanyl 24-hour transdermal patch were compared between 10 healthy elderly subjects 67-87 years and 6 young subjects 19-27 years. All 10 elderly subjects required patch removal prior to 24 h due to adverse effects versus none of the young subjects. The mean patch duration (PD) in elderly subjects was 11.7 +/- 4.9 h, yielding a mean area under the curve from 0 to 60 h (AUC0-60) of 20.4 +/- 10.3 ng h/ml versus a mean AUC0-60 of 21.0 +/- 10.4 ng h/ml in young subjects. Correcting AUC0-60 for PD (AUC0-60/PD) gave a mean value of 2.05 +/- 1.10 ng/ml for elderly subjects, which was significantly greater than the AUC0-60/PD of 0.88 +/- 0.44 ng/ml in young subjects (p = 0.034, Student's t test). The higher serum concentrations reflect increased absorption and/or decreased clearance in the elderly.