Antagonism of antinociception produced by intrathecal clonidine by ketorolac in the rat: the role of the opioid system.
Anesth Analg
; 90(5): 1152-6, 2000 May.
Article
en En
| MEDLINE
| ID: mdl-10781470
The management of severe pain may require "balanced analgesia," involving the use of analgesics with different modes of action. Clonidine, an alpha(2)-adrenoreceptor agonist produces analgesia by itself as well as when given with morphine and local anesthetics. Ketorolac is indicated for the management of moderately severe acute pain and causes analgesia equivalent to morphine. This study was designed to investigate whether the addition of ketorolac promotes antinociception produced by intrathecal administration of clonidine in male Sprague-Dawley rats. Intrathecal injection of clonidine (1-30 microg) induced a dose-dependent increase in antinociception as measured by the tail flick (TF) and hot plate tests. Ketorolac alone (150-600 microg) increased the antinociception by 50%-60% only in the TF test. Ketorolac (10 microg) decreased clonidine (10 microg)-induced antinociception from 69.1% +/- 7.8% to 23.5% +/- 1. 6% (P < 0.05) in the TF test and 35.7% +/- 4.7% to 4.5% +/- 0.1% (P < 0.05) maximum possible effect in the hot plate test. Ketorolac also antagonized the effect of 30 microg of clonidine. The opioid receptor antagonist naloxone antagonized the antinociceptive effect of clonidine and ketorolac, indicating the involvement of the opioid system in the antinociception produced by clonidine or ketorolac. However, neither clonidine nor ketorolac (10(-8) to 10(-3) M) inhibited the binding of specific ligands to mu-, delta-, and kappa-opioid receptors, indicating a lack of direct interaction of clonidine and ketorolac with opioid receptors. These results suggest that intrathecal injection of ketorolac antagonizes the antinociception produced by clonidine.
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Antiinflamatorios no Esteroideos
/
Clonidina
/
Agonistas alfa-Adrenérgicos
/
Receptores Opioides
/
Ketorolaco
/
Analgesia
/
Analgésicos
Límite:
Animals
Idioma:
En
Revista:
Anesth Analg
Año:
2000
Tipo del documento:
Article
País de afiliación:
Estados Unidos
Pais de publicación:
Estados Unidos