Ephedrine enhances the antinociceptive effect of dexmedetomidine in mice.

OBJECTIVES: Dexmedetomidine, a highly selective alpha-2-adrenoceptor agonist, was recently introduced into clinical practice for its sedative and analgesic properties. The purpose of this study was to evaluate whether the psychostimulant drug ephedrine has any effect on dexmedetomidine-induced antinociception and locomotor inhibitor activity in mice in acute application. METHODS: In both sexes of swiss albino mice; antinociception was assessed with hot-plate test and the locomotor, exploratory activities were assessed with holed open field test. The animals were received; saline + saline, ephedrine (10 mg/kg) + saline, saline + dexmedetomidine (15 μg/kg) and ephedrine (10 mg/kg) + dexmedetomidine (15 μg/kg), intraperitoneally, 30 min before hot plate or holed open field tests. RESULTS: In the hot plate test in mice, co-administration of 15 μg/kg dexmedetomidine with 10 mg/kg ephedrine intraperitoneally not only enhanced, but also prolonged the duration of antinociception induced by dexmedetomidine. At the same time, the locomotor inhibitory effect of dexmedetomidine was counteracted by ephedrine. CONCLUSION: We concluded that the combined administration of dexmedetomidine with ephedrine may have beneficial effects in the treatment of pain without causing sedation, which limits the use of dexmedetomidine as an analgesic in humans.