This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (7) Citing Articles via Google Scholar Google Scholar Articles by Hord, A. H. Articles by Azevedo, M. I. Search for Related Content PubMed PubMed Citation Articles by Hord, A. H. Articles by Azevedo, M. I. Related Collections Pain Pharmacology

---

REGIONAL ANESTHESIA

Systemic Tizanidine Hydrochloride (Zanaflex^TM) Relieves Thermal Hyperalgesia in Rats with an Experimental Mononeuropathy

Division of Pain Medicine, Department of Anesthesiology, Emory University School of Medicine, Atlanta, Georgia

Address correspondence and reprint requests to Allen H. Hord, MD, Department of Anesthesiology, Emory University School of Medicine, 1364 Clifton Rd., N.E., Atlanta, GA 30322.

We sought to determine whether tizanidine, an 2-agonist, relieved thermal hyperalgesia in rats with surgically induced neuropathic pain. We used a Sprague-Dawley rat model in which a chronic constriction of the sciatic nerve caused the rats to develop postural changes, mechanical allodynia, and thermal hyperalgesia. Thermal hyperalgesia was verified through paw withdrawal latency (PWL). PWL was tested before surgery, after surgery, and after injections with tizanidine (0.5, 1.0, or 2.0 mg/kg) or normal saline. Ambulatory and total movements were evaluated by placing the rats in activity cages. Thermal hyperalgesia was induced in all rats after surgery. Tizanidine, but not saline, caused a significant improvement in PWL (P < 0.05), with complete reversal of thermal hyperalgesia at all doses on postoperative Day 6. Rats who received tizanidine 2 mg/kg maintained complete reversal of thermal hyperalgesia through postoperative Day 9. Some sedation was observed with tizanidine 2 mg/kg, but not with smaller doses. We conclude that tizanidine effectively reversed thermal hyperalgesia in a rat model.

IMPLICATIONS: This study was conducted to determine whether tizanidine could attenuate the thermal hyperalgesia that occurs in rats with surgically induced chronic constriction of the sciatic nerve. Tizanidine was effective in reducing sensitivity to heat, as measured by paw withdrawal latency, and did not cause sedation at smaller doses.

This article has been cited by other articles:

				J. Wang, Y. Ren, X. Zou, L. Fang, W. D. Willis, and Q. Lin Sympathetic Influence on Capsaicin-Evoked Enhancement of Dorsal Root Reflexes in Rats J Neurophysiol, October 1, 2004; 92(4): 2017 - 2026. [Abstract] [Full Text] [PDF]

				J. S. Kroin, R. J. McCarthy, R. D. Penn, T. J. Lubenow, and A. D. Ivankovich Continuous Intrathecal Clonidine and Tizanidine in Conscious Dogs: Analgesic and Hemodynamic Effects Anesth. Analg., March 1, 2003; 96(3): 776 - 782. [Abstract] [Full Text] [PDF]

				A. H. Hord, D. D. Denson, and M. I. Azevedo Systemic Tizanidine Hydrochloride (ZanaflexTM) Partially Decreases Experimental Postoperative Pain in Rats Anesth. Analg., November 1, 2001; 93(5): 1307 - 1309. [Abstract] [Full Text] [PDF]