We believe that we are beginning to understand the biological cause of the neurotoxicity that happens after treatment with methotrexate. Dextromethorphan, an ingredient in common cough medicines, may be able to prevent and/or treat this neurotoxicity. We have given dextromethorphan to a small group of patients who developed severe neurologic side effects after methotrexate. All had a complete recovery within one day.
The purposes of this study are to find out whether dextromethorphan can prevent the short or long-term neurologic side effects of methotrexate, and whether dextromethorphan can improve symptoms of short-term neurologic side effects if they do occur.