title: Epinephrine administered with lidocaine solution does not worsen intrathecal lidocaine neurotoxicity in rats.
abstract: BACKGROUND
  Epinephrine can potentially worsen the neurotoxic effects of local anesthetics when used for spinal or epidural anesthesia. The vasoconstrictive property of epinephrine reduces dural blood flow, which in turn reduces the clearance of local anesthetics from the subarachnoid space. This study examined the histological and neurofunctional effects of intrathecally administered lidocaine combined with epinephrine in rats.
  
  
  METHODS
  Sixty-two rats were divided into 9 treatment groups: 5% or 7.5% lidocaine in 10% glucose solution with or without 0.1 or 0.5 mg/mL epinephrine, or epinephrine alone at 0.1 or 0.5 mg/mL in 10% glucose, or 10% glucose alone. Hind-limb motor function was evaluated immediately after drug injection by walking behavior. Sensory function was assessed by the response to radiant heat stimulation at just before and 1 week after the injection. Seven days after the injection, L3 spinal cord with anterior and posterior roots, the dorsal ganglion, and cauda equina were harvested and examined histologically.
  
  
  RESULTS
  Histological lesions were limited to the posterior root just at entry into the spinal cord in rats injected with 7.5% lidocaine, with and without epinephrine. No histological abnormalities were noted in other areas or other groups. There was no significant change in sensory threshold in all groups. Significantly, prolongation of gait recovery time was noted in 5% and 7.5% lidocaine with epinephrine groups compared with 5% or 7.5% lidocaine alone.
  
  
  CONCLUSIONS
  Intrathecal epinephrine prolonged the action of intrathecal lidocaine but did not worsen lidocaine-induced histological damage and functional impairment.
authors.affiliation: Departments of Pharmacy, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Komatsu
authors.forename: Tamie
authors.initials: T
authors.lastname: Takenami
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Nara
authors.forename: Saburo
authors.initials: S
authors.lastname: Yagishita
authors.forename: Chie
authors.initials: C
authors.lastname: Kurashige
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Okamoto
authors.forename: Kazuo
authors.initials: K
authors.lastname: Yago
mesh_terms: D000779:Anesthetics, Local / Q000008:administration & dosage / Q000633:toxicity*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D004347:Drug Interactions; D004837:Epinephrine / Q000008:administration & dosage / Q000633:toxicity*; D007278:Injections, Spinal; D008012:Lidocaine / Q000008:administration & dosage / Q000633:toxicity*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D020258:Neurotoxicity Syndromes / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D058748:Pain Perception / Q000187:drug effects; D017288:Pain Threshold / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function; D013116:Spinal Cord / Q000187:drug effects* / Q000473:pathology / Q000503:physiopathology; D013997:Time Factors; D014662:Vasoconstrictor Agents / Q000008:administration & dosage / Q000633:toxicity*
chemical_list: D000779:Anesthetics, Local; D014662:Vasoconstrictor Agents; D008012:Lidocaine; D004837:Epinephrine