title: Co-administration of memantine with epinephrine produces a marked peripheral action in intensifying and prolonging analgesia in response to local skin pinprick in rats.
abstract: The purpose of this study was to examine the effect of epinephrine as adjuvant for memantine or lidocaine as an infiltrative anesthetic. Using a rat model of cutaneous trunci muscle reflex (CTMR), we evaluated the effects of adding epinephrine to memantine or lidocaine on infiltrative cutaneous analgesia. Lidocaine, a known local anesthetic, was used as control. We found that epinephrine, memantine, and lidocaine produced a dose-dependent local anesthetic effect as infiltrative cutaneous analgesia. On a 50% effective dose (ED50) basis, the relative potencies were epinephrine [0.012 (0.006-0.020)μmol]>memantine [4.010 (3.311-4.988)μmol]>lidocaine [6.177 (5.333-7.218)μmol] (P<0.05 for each comparison). Mixtures of epinephrine (2.7nmol or 13.7nmol) with drugs (memantine or lidocaine) at ED50 or ED95, respectively, enhanced the potency and prolonged the duration of action on infiltrative cutaneous analgesia. Intraperitoneal injection of co-administration of drugs (memantine or lidocaine) at ED95 with epinephrine (13.7nmol) produced no cutaneous analgesia (data not shown). Epinephrine, memantine, and lidocaine were shown to have local anesthetic effects as infiltrative cutaneous analgesia. Epinephrine increased the duration and potency of memantine and lidocaine as an infiltrative anesthetic.
authors.affiliation: Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan; Department of Physical Therapy & Graduate Institute of Rehabilitation Science, China Medical University, Taichung, Taiwan.
authors.forename: Yu-Wen
authors.initials: YW
authors.lastname: Chen
authors.affiliation: Department of Food Sciences and Technology, Chia Nan University of Pharmacy and Science, Jen-Te, Tainan City, Taiwan; Department of Anesthesiology, Chi-Mei Medical Center, Yong Kang, Tainan City, Taiwan.
authors.forename: Jann-Inn
authors.initials: JI
authors.lastname: Tzeng
authors.affiliation: Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: He-Jia
authors.initials: HJ
authors.lastname: Pan
authors.affiliation: Institute & Department of Physical Therapy, National Cheng Kung University, Tainan, Taiwan. Electronic address: chhung@mail.ncku.edu.tw.
authors.forename: Ching-Hsia
authors.initials: CH
authors.lastname: Hung
authors.affiliation: Division of Physical Therapy, Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, Taiwan.
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Chen
authors.affiliation: Department of Medical Research, Chi-Mei Medical Center, Tainan, Taiwan.
authors.forename: Jhi-Joung
authors.initials: JJ
authors.lastname: Wang
mesh_terms: D000700:Analgesics / Q000627:therapeutic use; D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D000818:Animals; D004837:Epinephrine / Q000627:therapeutic use; D008012:Lidocaine; D008297:Male; D008559:Memantine / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy* / Q000503:physiopathology; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000503:physiopathology
chemical_list: D000700:Analgesics; D019162:Anesthetics, Combined; D000779:Anesthetics, Local; D008012:Lidocaine; D008559:Memantine; D004837:Epinephrine
keywords: Cutaneous analgesia; Epinephrine; Lidocaine; Local anesthetic; Memantine; Subcutaneous injection