Evaluation of the penetration depth of transdermally applied 3% GA MHPh 2Na-10% lidocaine gel in man.

In order to estimate the penetration depth of transdermal 3% GA MHPh 2Na-10% lidocaine gel mixture, the following physiological functions of the skin were examined before and after a 60 min occulusive application of the gel in 16 adult volunteers. Thermal sweat expulsins ceased completely on the gel-treated ventral surface of one forearm in all the firs 5 subjects, though it continued on the untreated contrast area of the other forearm. Sympathetic skin response (SSR) was also no longer induced on the gel-treated middle finger in 1 of another 3 subjects and was severely depressed in the other 2 subjects, while the SSR on the untreated index finger appeared constantly. Vasomotion of the skin circulation on another 3 subjects, remained unaffected on both the gel-treated and the untreated fingers. Extraction of a leg-hair in the treated area did not induce pain sensation in all the last 5 subjects. In addition to the transcellular main roots, some of the transcutaneously applied gel seems to penetrate deeply into the skin through the appendageal roots such as the eccrine sweat glands and the pilosebaceous glands.