Clinical experience with oral ketamine

Ketamine is a noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonis t used recently for analgesia in patients with chronic pain. Twenty-one pat ients with chronic neuropathic pain were treated with oral ketamine startin g at a divided dose of 100 mg/day and titrating upwards by 40 mg/day until efficacy was reached, or until side effects became limiting. A retrospectiv e chart review was conducted to evaluate the analgesic efficacy and side ef fects of the treatment. Nine patients discontinued Ketamine because of into lerable side effects, four patients experienced few or no side effects but had no discernible benefit, four others had equivocal responses, Four patie nts have continued oral ketamine for long periods. One patient has had no s ignificant benefit or side effects but continues to use ketamine 500 mg/day and three people have used doses ranging from I 100-240 mg day for over 1 year duration and have reported improvements in pain and decreased use of a nalgesics. The analgesic benefits of Ketamine appeared to be most pronounce d in, but not limited to, patients with pain histories of lass than 5 years . (C) U.S. Cancer Pain Relief Committee, 1999.