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.