The evaluation of various antihistamines as local anesthetic agents.

There have been some recent studies on the clinical uses of the antihistamines as local anesthetic agents (1, 2, 3, 4). These have included the use of the antihistamines as local anesthetics for minor surgical procedures, nerve blocks and spinal anesthesia. The authors have compared the particular antihistamines under evaluation to procaine and, in general, have obtained results superior to those of procaine. Toxic effects due to the local injection of the antihistamines have been reported, however (5, 3). These consist of erythema, necrosis and ulceration at the site of injection. These reports have probably been the cause of the limited clinical acceptance of the antihistamines as local anesthetics. The purpose of this study is to evaluate further the local anesthetic action and the side effects of four antihistamines.