A new clinical trial has been designed to evaluate the diagnostic performance of orally administered fluorescein sodium for the confirmation of authentic urine samples in adults with substance use disorder. This study aims to determine whether oral fluorescein sodium can be used to confirm the authenticity of point-of-care urine samples in adults with substance use disorder.

Urine drug testing is widely used in the treatment of substance use disorder, yet sample substitution remains an ongoing concern. Current verification methods, such as temperature checks, are helpful but not foolproof and may fail to detect all cases of tampering. As part of the trial, participants will ingest a beverage containing fluorescein (or a placebo), and their urine will be tested shortly afterward to detect the presence of fluorescence. The goal is to validate a simple and reliable method to reduce sample tampering or substitution in urine drug testing.

The study will be sponsored by UpTru Inc., a private diagnostics company focused on improving the accuracy of urine drug testing, in order developing a method that uses an orally ingested fluorescent compound to confirm that a urine sample comes from the tested individual, aiming to reduce substitution or tampering in substance use monitoring.

According to the Safer Opioid Prescribing HARMS program, the three most common ways of  tampering with a urine sample include dilution of the sample, addition of adulterants or oxidizing agents, and substitution with another urine specimen. Urine substitution is a form of tampering in which an individual provides someone else’s urine to avoid detection of drugs. This may involve using drug-free urine or urine containing an expected drug profile to pass routine testing. Currently, a common way to detect substitution is by measuring sample temperature, since freshly voided urine should be between 32–38°C and remain at least 32–33°C within 15 minutes of collection.