AIM: To study the influence of chronological age on fentanyl permeation through human skin in vitro using static diffusion cells. Elderly individuals are known to be more sensitive to opioids and obtain higher plasma concentrations following dermal application of fentanyl compared to younger individuals. The influence of age - as an isolated pharmacokinetic term - on the absorption of fentanyl has not been previously studied.

METHOD: Human skin from 30 female donors was mounted in static diffusion cells, and samples were collected during 48 h. Donors were divided into three age groups: <30 years of age (n = 6), ≥30 and <60 years of age (n = 18) and ≥60 years of age (n = 6).

RESULTS: The youngest group had a significantly higher mean absorption (3,100 ng/cm(2)) than the two other groups (2,000 and 1,475 ng/cm(2), respectively) and a significant larger AUC (young age group: 9,393 ng; middle and old age groups: 5,922 and 4,050 ng, respectively). Furthermore, the lag time and absorption rate were different between the three groups, with a significantly higher rate in the young participants versus the oldest participants.

CONCLUSION: We demonstrate that fentanyl permeates the skin of young individuals in greater amounts and at a higher absorption rate than in middle-aged and old individuals in vitro.