Dextromethorphan-induced delirium and possible methadone interaction.
BACKGROUND
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.


METHODS
An 83-year-old woman was evaluated for delirium, hypersomnia, confusion, lethargy, impaired concentration, and poor food intake. Symptoms resolved soon after discontinuing dextromethorphan.


CONCLUSIONS
Vulnerability to delirium was potentially caused by coadministration of methadone, which can inhibit the CYP2D6 isozyme.


CONCLUSIONS
Evaluation of delirium should include close investigation of the patient's medications for potential interactions with dextromethorphan.
Lotrich
Francis E
FE
Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania 15213, USA. lotrichfe@upmc.edu
Rosen
Jules
J
Pollock
Bruce G
BG
D000368:Aged; D000701:Analgesics, Opioid / Q000009:adverse effects* / Q000627:therapeutic use; D000996:Antitussive Agents / Q000009:adverse effects* / Q000627:therapeutic use; D003371:Cough / Q000150:complications / Q000188:drug therapy; D003693:Delirium / Q000139:chemically induced* / Q000523:psychology; D003866:Depressive Disorder / Q000150:complications / Q000188:drug therapy; D003915:Dextromethorphan / Q000009:adverse effects* / Q000627:therapeutic use; D004347:Drug Interactions; D005260:Female; D006801:Humans; D008691:Methadone / Q000009:adverse effects* / Q000627:therapeutic use; D010146:Pain / Q000188:drug therapy / Q000523:psychology; D017367:Selective Serotonin Reuptake Inhibitors / Q000627:therapeutic use; D020280:Sertraline / Q000627:therapeutic use
D000701:Analgesics, Opioid; D000996:Antitussive Agents; D003915:Dextromethorphan; D008691:Methadone; D017367:Selective Serotonin Reuptake Inhibitors; D020280:Sertraline