Effects of local anesthetics on tactile sensitivity thresholds for cutaneous and mucous membranes.

New, reliable, and precise methods for measuring absolute pressure sensitivity in mucous membranes and on intact skin are described. Studies were conducted to determine how local anesthetics (phenol and sodium phenolate and Benzocaine) affect tactile sensitivity thresholds in the oropharynx and on the intact skin of the volar surface of the forearms, ankles, knees, elbows, and dorsum of the hands. Gargling and expectorating a solution containing phenol had a significantly greater anesthetic effect on the mucous membranes of the oropharynx than spraying and swallowing, which, in turn, had a greater effect than drinking the solution. Compared with ethanol and petroleum jelly (Vaseline), the topical application of Benzocaine (0, .5, 1, 3, and 5% solutions in 100% ethanol) significantly increased the tactile sensory thresholds on the volar surface of the forearm. A highly significant loss of tactual sensitivity of the oropharynx was demonstrated in smokers.