Background: The activity of corticosteroids is dependent on their ability to penetrate the skin. Laurocapram is a skin penetration enhancer that facilitates absorption of cutaneously applied substances.Objective: The purpose of these studies was to determine whether the addition of laurocapram to a topical triamcinolone acetonide (TA) 0.05% cream formulation would improve the rate of percutaneous penetration and hence the activity of the corticosteroid, as measured by increased vasoconstriction (ie, skin blanching).Methods: Thirty healthy subjects participated in each of 2 double-blind, randomized, multiple-point vasoconstriction studies comparing the TA 0.05%/laurocapram (TNX) formulation with the placebo vehicle (TNX without TA), the TNX formulation without laurocapram (TN), and 3 mid-strength to potent corticosteroid formulations (fluocinolone acetonide 0.025% ointment, betamethasone dipropionate 0.05% cream, and fluocinonide 0.05% cream). Duplicate sites on subjects' forearms were exposed to ~10 mg of each formulation for 4 or 6 hours. Sites were washed and evaluated 1 hour later (ie, 5 or 7 hours after application). Skin blanching activity, a surrogate marker of clinical activity and the rate of percutaneous penetration, was assessed 12 times over a 57-hour period using a 4-point scale (0 = none; 1 = mild; 2 = moderate; 3 = marked).Results: In the first study, the vasoconstriction effect of the TNX formulation after 4 hours of exposure to the cream was significantly greater than that of TN (P < 0.01). In the second study, after 6 hours of exposure, the skin blanching activity of TNX was significantly greater (P = 0.05) than that of fluocinolone acetonide 0.025% ointment, a mid-strength corticosteroid, and betamethasone dipropionate 0.05% cream, a potent corticosteroid, and slightly less than that of fluocinonide 0.05% cream, also classified as a potent corticosteroid.Conclusions: Based on the correlation between the vasoconstrictor activity of corticosteroids and their clinical activity, the results suggest that the addition of laurocapram enhances the skin penetration of, and hence the activity of, topical corticosteroids and may improve treatments for corticosteroid-responsive dermatoses.