ANTINOCICEPTIVE ACTIVITY OF MIDAZOLAM IN SHEEP

The purpose of this study was to examine the effects of midazolam on t he nociceptive threshold responses in sheep. The intravenous administr ation of midazolam (0.1-0.3 mg/kg) produced a significant dose-depende nt elevation of the mechanical and thermal nociceptive thresholds. The intravenous administration of flumazenil (20 mu g/kg) markedly attenu ated the antinociceptive activity of midazolam in the mechanical nocic eptive test, whereas intravenous naloxone (0.2 mg/kg) had no significa nt effect on midazolam-mediated analgesia. The intrathecal administrat ion of midazolam (1 mg), via chronically implanted cervical subarachno id catheters, produced a significant elevation in the mechanical thres hold responses. These results indicate that midazolam has antinocicept ive actions in the sheep and suggest that this effect: is, at least pa rtially, mediated at the spinal level.