Dexmedetomidine enhances the local anesthetic action of lidocaine via an α-2a adrenoceptor

Tatsush Yoshitomi, Atsushi Kohjitani, Shigeru Maeda, Hitoshi Higuchi, Masahiko Shimada, Takuya Miyawaki

Research output: Contribution to journalArticle

102 Citations (Scopus)

Abstract

BACKGROUND: Clonidine, an α-2 adrenoceptor agonist, is a common adjunct in both central and peripheral blocks. Dexmedetomidine, a more selective α-2 adrenoceptor agonist, is also known to enhance central neural blockades. Its peripheral effect, however, has not been fully elucidated. Thus, we evaluated the effect of dexmedetomidine and other α-2 adrenoceptor agonists on the local anesthetic action of lidocaine at the periphery and explored the mechanism involved. METHODS: α-2 Adrenoceptor agonists, including dexmedetomidine, clonidine, and oxymetazoline, combined with lidocaine were intracutaneously injected into the back of male guinea pigs. The test of six pinpricks was applied every 5 min until 60 min after the injection. The number of times which the prick failed to elicit a response during the 60-min period was added and the sum served as an anesthetic score indicating the degree of local anesthesia. Differences from the control value within the group were analyzed using an analysis of variance followed by a post hoc Dunnett's test. Furthermore, we evaluated the antagonism of the effect of dexmedetomidine by yohimbine, an α-2A, 2B, and 2C adrenoceptor antagonist, or prazosin, an α-1, α-2B, and 2C adrenoceptor antagonist, analyzed using a two-way analysis of variance. RESULTS: All α-2 adrenoceptor agonists enhanced the degree of local anesthesia of lidocaine in a dose-dependent manner. Furthermore, yohimbine inhibited the effect of dexmedetomidine, whereas prazosin did not. CONCLUSION: We demonstrated that α-2 adrenoceptor agonists enhanced the local anesthetic action of lidocaine, and suggest that dexmedetomidine acts via α-2A adrenoceptors.

Original languageEnglish
Pages (from-to)96-101
Number of pages6
JournalAnesthesia and Analgesia
Volume107
Issue number1
DOIs
Publication statusPublished - Jul 2008

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Dexmedetomidine
Lidocaine
Local Anesthetics
Adrenergic Receptors
Yohimbine
Prazosin
Clonidine
Local Anesthesia
Analysis of Variance
Oxymetazoline
Anesthetics
Guinea Pigs

ASJC Scopus subject areas

  • Anesthesiology and Pain Medicine

Cite this

Dexmedetomidine enhances the local anesthetic action of lidocaine via an α-2a adrenoceptor. / Yoshitomi, Tatsush; Kohjitani, Atsushi; Maeda, Shigeru; Higuchi, Hitoshi; Shimada, Masahiko; Miyawaki, Takuya.

In: Anesthesia and Analgesia, Vol. 107, No. 1, 07.2008, p. 96-101.

Research output: Contribution to journalArticle

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AB - BACKGROUND: Clonidine, an α-2 adrenoceptor agonist, is a common adjunct in both central and peripheral blocks. Dexmedetomidine, a more selective α-2 adrenoceptor agonist, is also known to enhance central neural blockades. Its peripheral effect, however, has not been fully elucidated. Thus, we evaluated the effect of dexmedetomidine and other α-2 adrenoceptor agonists on the local anesthetic action of lidocaine at the periphery and explored the mechanism involved. METHODS: α-2 Adrenoceptor agonists, including dexmedetomidine, clonidine, and oxymetazoline, combined with lidocaine were intracutaneously injected into the back of male guinea pigs. The test of six pinpricks was applied every 5 min until 60 min after the injection. The number of times which the prick failed to elicit a response during the 60-min period was added and the sum served as an anesthetic score indicating the degree of local anesthesia. Differences from the control value within the group were analyzed using an analysis of variance followed by a post hoc Dunnett's test. Furthermore, we evaluated the antagonism of the effect of dexmedetomidine by yohimbine, an α-2A, 2B, and 2C adrenoceptor antagonist, or prazosin, an α-1, α-2B, and 2C adrenoceptor antagonist, analyzed using a two-way analysis of variance. RESULTS: All α-2 adrenoceptor agonists enhanced the degree of local anesthesia of lidocaine in a dose-dependent manner. Furthermore, yohimbine inhibited the effect of dexmedetomidine, whereas prazosin did not. CONCLUSION: We demonstrated that α-2 adrenoceptor agonists enhanced the local anesthetic action of lidocaine, and suggest that dexmedetomidine acts via α-2A adrenoceptors.

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