Francis E Lotrich1, Jules Rosen, Bruce G Pollock. 1. Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA. lotrichfe@upmc.edu
Abstract
INTRODUCTION: Dextromethorphan is a commonly used antitussive agent that can be purchased over the counter. It is metabolized primarily by the cytochrome P450 (CYP) 2D6 isozyme. Methadone has been found to inhibit CYP2D6, indicating a potential for interaction with dextromethorphan. CASE SUMMARY: An 83-year-old woman was evaluated for delirium, hypersomnia, confusion, lethargy, impaired concentration, and poor food intake. Symptoms resolved soon after discontinuing dextromethorphan. DISCUSSION: Vulnerability to delirium was potentially caused by coadministration of methadone, which can inhibit the CYP2D6 isozyme. CONCLUSION: Evaluation of delirium should include close investigation of the patient's medications for potential interactions with dextromethorphan.
INTRODUCTION:Dextromethorphan is a commonly used antitussive agent that can be purchased over the counter. It is metabolized primarily by the cytochrome P450 (CYP) 2D6 isozyme. Methadone has been found to inhibit CYP2D6, indicating a potential for interaction with dextromethorphan. CASE SUMMARY: An 83-year-old woman was evaluated for delirium, hypersomnia, confusion, lethargy, impaired concentration, and poor food intake. Symptoms resolved soon after discontinuing dextromethorphan. DISCUSSION: Vulnerability to delirium was potentially caused by coadministration of methadone, which can inhibit the CYP2D6 isozyme. CONCLUSION: Evaluation of delirium should include close investigation of the patient's medications for potential interactions with dextromethorphan.