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Abstract Ts were compared with those obtained from administration of lidocaine-containing standard liposomes. In rats, subcutaneous injections of 2% lidocaine solution and of liposomal or transfersomal suspension resulted in a strong initial analgesic effect that decayed within 6–7 min. Characteristic withdrawal time is approximately 30 s. Dermally applied analgesic transfersomes, by contrast, increased heat stimulus reaction to >70 s, 130% longer than in controls that received a placebo or a standard aqueous lidocaine solution. In humans, we tested two groups of nine male and female volunteers, aged between 25 and 60 yr, for pain-suppressing activity assessed by the pinprick method. Each subject received a total of 0.5 mL of a transfersomal preparation containing 7% lidocaine or 4% tetracaine over a forearm area of 9 cm. We conclude that the effectiveness of dermally applied anesthetic transfersomes is similar to that of the corresponding subcutaneous injections of similar drug quantities and that optimally designed transfersomes offer a suitable and promising means for the noninvasive treatment of local pain with direct, topical drug application. Address correspondence to Dr. Cevc, Medizinische Biophysik-Forschungslaboratorien, Urologische Klinik und Poliklinik der Technischen Universitat München, Klinikum r.d. I., Ismaningerstrasse 22, W-8000 Munich 8, E.C. Accepted for publication May 29, 1992. © 1992 International Anesthesia Research Society...