Percutaneous absorption of salicylic Acid after administration of trolamine salicylate cream in rats with transcutol(®) and eucalyptus oil pre-treated skin

Purpose: This study was conducted to assess the effect of skin pre-treatment with Transcutol(®) and eucalyptus oil on systemic absorption of topical trolamine salicylate in rat.

Methods: Pharmacokinetic parameters of salicylic acid following administration of trolamine salicylate on rat skin pre-treated with either Transcutol(®) or eucalyptus oil were determined using both non-compartmental and non-linear mixed effect modeling approaches and compared with those of control group.

Results: Median (% of interquartile range/median) of salicylic acid AUC0-8hr (ng/mL/hr) values in Transcutol(®) or eucalyptus oil treated rats were 2522(139%) and 58976(141%), respectively as compared to the 3023(327%) of the control group. Skin pre-treatment with eucalyptus oil could significantly decrease extravascular volume of distribution (V/F) and elimination rate constant (k) of salicylic acid.

Conclusion: Unlike Transcutol(®), eucalyptus oil lead to enhanced transdermal absorption of trolamine salicylate through rat skin.

Eucalyptus oil; Non-linear mixed effect modeling; Rat; Transcutol; Transdermal absorption; Trolamine salicylate.