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Epinephrine Administered With Lidocaine Solution Does Not Worsen Intrathecal Lidocaine Neurotoxicity in Rats
  1. Toshiaki Komatsu*,
  2. Tamie Takenami, MD, PhD,
  3. Yoshihiro Nara, DVM,
  4. Saburo Yagishita, MD, PhD,
  5. Chie Kurashige, MD,
  6. Hirotsugu Okamoto, MD, PhD and
  7. Kazuo Yago, PhD*
  1. Departments of *Pharmacy and †Anesthesiology, Kitasato University School of Medicine; and ‡Department of Pathology, Kanagawa Rehabilitation Center, Kanagawa, Japan.
  1. Address correspondence to: Tamie Takenami, MD, PhD, Department of Anesthesiology, Kitasato University School of Medicine, 1-15-1 Kitasato, Sagamihara, Kanagawa 252-0374, Japan (e-mail: takenami{at}


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.

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  • The authors declare no conflicts of interest.

    Joseph M. Neal, MD, served as editor-in-chief for this article.