Previous administration of indomethacin or naloxone did not influence ketorolac antinociception in mice.

We studied the effects of the inhibition of prostaglandin biosynthesis and opioid antagonism in the antinociceptive action of ketorolac using the mouse acetic acid writhing test. Ketorolac was administered via the intraperitoneal, intrathecal, or intracerebroventricular routes. Although the ketorolac induced a significant dose-dependent antinociceptive effect, the intracerebroventricular administration was the most effective route. Indomethacin and naloxone pretreatments did not change the ketorolac-induced antinociception. The present findings suggest that this antinociceptive action of ketorolac is not mediated by the inhibition of prostaglandin biosynthesis nor by activation of opioid receptors.