THE DEXTROMETHORPHAN DEFENSE - DEXTROMETHORPHAN AND THE OPIOID SCREEN

Objective: To determine whether a single oral dose of dextromethorphan produces a falsely positive qualitative urine opioid screen. Methods: A prospective, randomized, triple-blind, placebo-controlled, crossove r exposure study design was used. Twenty adult volunteers participated . All were without routine medications, not pregnant or lactating, wit hout known sensitivity to dextromethorphan, and negative for urine tox icologic screening immediately prior to testing. These volunteers unde rwent three separate urine Enzyme-Multiplied Immunoassay Technique (EM IT) opioid screens. Each screen was performed six hours after the subj ect had; Ingested a single liquid medication, either dextromethorphan, codeine, or placebo. Each volunteer took all three medications random ly, at least 72 hours apart. Half of the volunteers took the standard adult dose of dextromethorphan (20 mg), while the other half ingested twice this amount (40 mg). The amounts of codeine (30 mg) and sucrose placebo (10 mt) remained constant. Results: For these young adults (me an age +/- SD = 30.7 +/- 2.8 years), all urine EMIT assays six hours a fter ingestion of dextromethorphan, at both dosage levels, were negati ve for opioids and all other drugs. All assays after codeine and place bo ingestion were positive and negative for opioids, respectively. Con clusion: Although dextromethorphan is structurally similar to opioid d rugs, the ingestion of a single normal (or even twice normal) dose of dextromethorphan is not likely to produce a falsely positive six-hour urine opioid EMIT screen.