Of the small number of NMDA receptor antagonists currently available for clinical use, most, unfortunately, either have a narrow therapeutic window or require parenteral administration. Dextromethorphan, best known for its use as an antitussive agent, is dosed orally and shows activity as a noncompetitive NMDA antagonist. Multiple trials, however, generally have not shown dextromethorphan to be effective in treating neuropathic pain.