Epidural clonidine analgesia for intractable cancer pain: phase I.

Intrathecally administered clonidine has been reported to produce analgesia in cancer patients tolerant to intrathecal opiates. To assess the efficacy, safety, and appropriate dose of epidurally administered clonidine for the treatment of cancer pain, clonidine (range, 100-900 micrograms in 100-micrograms increments) was injected in nine patients with severe, intractable cancer pain. Clonidine produced analgesia, as measured by change in verbal pain scores, lasting more than 6 h. Clonidine also decreased blood pressure, although this effect was well tolerated and no patient met criteria for receiving iv ephedrine (greater than 30% decrease in mean arterial pressure not responsive to 500 ml iv crystalloid infusion). Clonidine decreased heart rate 10-30% and produced transient sedation. Serum glucose and cortisol and oxyhemoglobin saturation were not altered by clonidine. Clonidine was absorbed in a dose-dependent manner into the systemic circulation, although absorption and elimination kinetics were highly variable. Following study seven patients received epidural clonidine/morphine infusions at home for periods of up to 5 months with sustained analgesia. These results suggest that epidurally administered clonidine may offer effective analgesia in patients with severe, intractable cancer pain.