Hemodynamic effects of stellate ganglion block: analysis using a model of aortic input impedance.

A subanesthetic dose of oral ketamine proved able to reduce chronic pain. These findings support the idea that norketamine, a metabolite of ketamine, may have played an important part in the analgesia observed in these chronic-pain patients,4 although we did not measure the plasma concentration of norketamine. We did not observe serious adverse events or tolerance to oral ketamine in the present study. Oral ketamine may be useful for the long-term treatment of chronic neuropathic pain.