To the Editor.
—I wish to alert physicians that a frequently prescribed nonsteroidal anti-inflammatory drug (NSAID), oxaprozin (Daypro, GD Searle & Co, Skokie, Ill), can cause a false-positive result for benzodiazepines on urine "drug abuse" panels.We were first alerted to this problem when a patient presented after being accused of using diazepam (Valium, Roche Products Inc, Manati, Puerto Rico). She had voluntarily joined a drug detoxification program for cocaine abuse 3 months prior. However, for 3 weeks, her program coordinator had threatened to remove her from the program and speak to her employer because results of weekly urine tests performed at a commercial laboratory showed "Valium or some similar drug." She was taking levothyroxine sodium (Synthroid, Boots Pharmaceuticals Inc, Lincolnshire, Ill) and wondered if this might be the reason the urine sample tested positive; she vehemently denied drug use. On questioning, she was also taking an "arthritis" medicine (oxaprozin)
Pulini M. False-positive Benzodiazepine Urine Test Due to Oxaprozin. JAMA. 1995;273(24):1905. doi:10.1001/jama.1995.03520480023025