4 YEARS TREATMENT WITH KETAMINE AND A TRIAL OF DEXTROMETHORPHAN IN A PATIENT WITH SEVERE POSTHERPETIC NEURALGIA

N-methyl-D-aspartat (NMDA) receptors are involved in the development o f neuropathic pain. Ketamine, a non-competitive NMDA receptor antagoni st, has in several case reports given pain relief but efficacy in dosa ges tolerated in long-term ketamine treatment is unknown. Another subs tance with an antagonist action at NMDA receptors and which is approve d for peroral administration is dextromethorphan. Ln a randomized stud y dextromethorphan was no better than placebo for neuropathic pain but this does not exclude efficacy in selected patients. We report a pati ent with severe post-herpetic pain resistant to conventional pain trea tment which was treated with ketamine for 4 years with good pain relie f. The practical application of long-term treatment in different admin istration forms of ketamine is described. The patient also responded w ith pain relief in a double-blind trial with oral dextromethorphan.