科研之友
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摘要
A wide range of doses has been suggested for intrathecal clonidine, but no dose-ranging study has examined analgesic effects below 100 g. The primary aim of this volunteer study was to assess the dose vs analgesic effect relationship for doses of intrathecal clonidine below 100 mu g. After IRB approval and signed informed consent, 11 healthy female volunteers participated in this randomized, double-blinded, cross-over study using a dose-ranging sparse-sampling technique. Participants received intrathecal clonidine (doses 0100 g; n10) and intrathecal bupivacaine (doses 08.8 mg; n9) on separate study days. At baseline, 30, and 60 min from drug administration, experimental heat pain tolerance was assessed at both a lumbar and a cranial dermatome. Heat and cold perception thresholds were assessed at the same time intervals. Heart rate (HR), arterial pressure, and forearmfinger and toe-leg cutaneous temperature gradients (T-fingerarm and T-toeleg) were used as measures of sympatholysis. Both intrathecal clonidine and bupivacaine caused significant, dose-dependent analgesic effects at the leg but not the head. Significant analgesia to experimental heat pain was detected above 25 g clonidine and 3 mg bupivacaine. Administration of bupivacaine but not clonidine resulted in a significant dose-related decrease in HR and T-toeleg; neither drug caused dose-related sympatholytic effects in the doses used. After 50 g clonidine or 5 mg bupivacaine, the heat pain tolerance increased by 1C, similar to the analgesic effect of 5 mg epidural morphine or 30 g epidural fentanyl in previous studies using this experimental heat pain model. Our results provide additional data for rational dose selection of intrathecal clonidine.
- 出版日期2013-8
