Analgesic and sympatholytic effects of low-dose intrathecal clonidine compared with bupivacaine: a dose-response study in female volunteers

After 50 µg clonidine or 5 mg bupivacaine, the heat pain tolerance increased by ∼1°C, similar to the analgesic effect of 5 mg epidural morphine or 30 µg epidural fentanyl in previous studies using this experimental heat pain model. Our results provide additional data for rational dose selection of intrathecal clonidine.