0758 Solriamfetol and Prevalence of False-Positive Urine Toxicology Screens for Amphetamines

Abstract Introduction Solriamfetol has been reported to cause a false positive for amphetamines on urine toxicology screening. Similarities in the chemical structures and mechanisms of action (competitive inhibition resulting in reuptake inhibition of the sympathomimetic amines) may result in solriamfetol potentially binding to assay reagents that were designed for amphetamines, leading to false positive screens on many of the commonly used immunoassay platforms. As part of standard practice at our institution, urine toxicology screens are performed on patients taking solriamfetol. We sought to determine the rate of false positive amphetamine urine toxicology screens in patients on solriamfetol. Methods This was an IRB approved retrospective chart review. Patients prescribed solriamfetol at our institutions had their charts extracted for age, gender, race, BMI, sleep diagnosis, duration and dose of solriamfetol therapy, urine toxicology results (including confirmatory testing of positive screens, if available), concomitant medications and medical comorbidities. All controlled substance use was verified in the state-reported controlled substance use monitoring system. Results We found 41 patients on solriamfetol that underwent urine toxicology screening. Demographics included an average age of 46 years old, average BMI of 29.8 kg/m2, and 78% were women. Diagnoses included were idiopathic hypersomnia (6 (14.6%)), residual sleepiness from OSA (16 (39%)), and narcolepsy (19 (46.3%)). Eight (19.5%) of these patients had positive urine toxicology amphetamine screens at some point while taking solriamfetol, though 5 of these were on amphetamine–dextroamphetamine during their urine toxicology screens. Three (7.3%) remaining patients had positive urine toxicology screens for amphetamines despite no concomitant amphetamine use (verified) or illicit drug use. Confirmatory testing in 2 of 3 was negative for amphetamines (the 3rd did not have a confirmation test). In addition, 2 of 3 were also on fluoxetine at the time of screening, but the dose of fluoxetine was deemed to be insufficient to interfere with the testing results. Conclusion 7% of patients using solriamfetol had false positive urine toxicology screens for amphetamines in this study. Prescribers of solriamfetol should be aware of this potential issue and perform confirmatory testing when urine toxicology screens are positive for amphetamines without a reasonable explanation. Support (if any)