Dextromethorphan Abuse Among Opioid-Dependent Patients

Among opioid-dependent patients on maintenance therapy, concomitant drug abuse is a serious problem. Dextromethorphan, an over-the-counter antitussive agent that can be purchased without prescription, is a drug with a high potential for misuse, especially when consumed in high doses.The objective of this study was to investigate possible abuse of dextromethorphan among substituted opioid-dependent patients and comparison of subjective and objective findings.Due to its ability to increase serotonin levels, opioid-dependent patients may be particularly susceptible to dextromethorphan misuse. Dextromethorphan misuse may have side effects, including psychiatric symptoms and serotonin syndrome, and may induce assault, suicide, or homicide.

A total of 104 opioid-dependent patients in maintenance treatment were included in this cross-sectional study conducted in the outpatient department of the Psychiatric Hospital, University of Zurich. Study participants were divided into 2 groups based on laboratory results: dextromethorphan abusers (n = 12) and nonabusers (n = 92). The objective use and concentrations of dextromethorphan was detected using 3-month hair toxicology analysis.Statistical analysis was performed by using χ test, Student t test, Mann-Whitney U test, and Barnard exact test.

Dextromethorphan was abused by 12 (11.5%) patients, 11 (91.7%) of whom did not report concomitant abuse of dextromethorphan but were identified through hair analysis. In general, there were significant differences among patients abusing dextromethorphan compared with nondextromethorphan consumers in terms of trauma due to sexual maltreatment/violence, multiple traumas, or harmful use of hallucinogenic drugs.

Further studies are necessary to examine dextromethorphan and its impact on patients with psychiatric comorbidities and psychiatric medication. According to literature, there is a significant drug interaction risk due to the impact of dextromethorphan misuse on serotonin syndrome and psychiatric symptoms.1-3 We recommend active inquiry into and testing for concomitant drug abuse among substituted opioid-dependent patients to reduce the risk of drug interactions and side effects in this especially vulnerable group of patients.