[Parenteral administration of low dose ketamine for the treatment of neuropathic pain in cancer patients].

In three patients, a 52-year-old woman with skeletal metastases from bladder carcinoma, a 54-year-old man with metastasised thyroid carcinoma and a 40-year-old man with a non-Hodgkin lymphoma, neuropathic pain developed that could not be alleviated adequately by patient-controlled opioid administration. It is known that ketamine, a N-methyl-D-aspartate (NMDA) receptor antagonist, can improve opioid-induced analgesia. Pending invasive therapy, the three patients were given a continuous low dose of parenteral ketamine (2-5 micrograms/kg/min). The pain in the first two patients responded so well to ketamine that they decided to waive the invasive pain treatment and to continue the ketamine infusion at home until death. In the third patient, the addition of ketamine resulted in an adequate level of analgesia during the waiting period for invasive treatment with an intrathecal catheter.