Canadian Journal of Anesthesia, Vol 30, 501-505, Copyright © 1983 by Canadian Anesthesiologists' Society

Analgesic Properties of Meperidine, Amitriptyline and Phenelzine in Mice

¹ Department of Anesthesiology, New York University Medical Center

Address correspondence to: J. Chalon MD, Dept. of Anesthesiology, New York University Medical Center, 550 First Avenue, New York, N.Y. 10016, U.S.A.

Sixty-three white Swiss Webster mice were divided into seven equal groups. Their tolerance to pain (heat applied to the tail by a test tube containing hot water at a temperature measured by telethermometry) was assessed before and after intraperitoneal injection of (1) physiologic saline; (2) meperidine 14 µg·g^-1; (3) amitriptyline 6µg·g^-1 (4) amitriptyline 12µg·g^-1; (5) phenelzine 1.5 µg·g^-1; (6) phenelzine 3 µg·g^-1; and (7) amitriptyline 6µg·g^-1 plus phenelzine 1.5 µg·g^-1. All postinjection tests were conducted 45 and 90 minutes after administration, and repeated 24 hours later. No significant difference in pain threshold was noted in any pre-injection test or in any test conducted with physiologic saline. By 90 minutes post-injection, all groups receiving drugs developed increased tolerance to pain. Mice which had received phenelzine plus amitriptyline, or either dose of phenelzine were more tolerant to pain for up to 24 hours than mice which had received physiologic saline. The most marked increases in tolerance to pain were seen with 1.5 µg·g^-1 and 3 µg·g^-1 of phenelzine and phenelzine plus amitriptyline. However, phenelzine was more effective and had a longer-lasting effect than either dose of amitriptyline, or meperidine. The combination of phenelzine plus amitriptyline was no more effective than phenelzine alone.

Key Words: PAIN: experimental, acute • ANALGESICS: meperidine • ATARACTICS: antidepressants, tricyclic • amitriptyline, phenelzine