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Lack of stereoselectivity for the antiallodynic effect of mexiletine in spinally injured rats
Author(s) -
Wu WeiPing,
Nordmark Jan,
WiesenfeldHallin Zsuzsanna,
Xu XiaoJun
Publication year - 2000
Publication title -
european journal of pain
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.305
H-Index - 109
eISSN - 1532-2149
pISSN - 1090-3801
DOI - 10.1053/eujp.2000.0201
Subject(s) - mexiletine , neuropathic pain , pharmacology , analgesic , medicine , allodynia , anesthesia , receptor , nociception , hyperalgesia
Systemically administered mexiletine, an antiarrhythmic, has been shown to also possess analgesic properties in some conditions of neuropathic pain. It has been suggested that the analgesic effect of mexiletine may be derived from the action of one of its optical isomers, (+)(S)‐mexiletine. In the present study, we have compared the effects of systemic (−)‐(R)‐ and (+)‐(S)‐mexiletine, on chronic mechanical allodynia‐like behaviour in spinally injured rats, a model of central neuropathic pain in which racemic mexiletine has been shown to be active. I.p. racemic mexiletine as well as (−)‐(R)‐ and (+)(S)‐mexiletine at 25 mg/kg all produced significant, but brief, alleviation of mechanical allodynia in a similar fashion as assessed with von‐Frey hair elicited vocalization in the spinally injured rats. A slight increase in motor impairment was observed in all three groups which reached statistical significance for the racemic mexiletine and (+)‐(S)‐mexiletine. Our results suggest that both isomers of mexiletine contribute to the antiallodynic effect in this model of central pain.