A stable-labeled internal standard suitable for quantitation of Zolpidem Phenyl-4-carboxylic acid levels in urine or other matrices by LC/MS or GC/MS for testing applications in clinical toxicology, forensic analysis, or urine drug testing. Zolpidem Phenyl-4-carboxylic acid is the major urinary metabolite of zolpidem, accounting for 51% of an administered dose. Literature references indicate the metabolite can be found in urine for 2-3 days following ingestion of a single therapeutic dose of zolpidem.1 Zolpidem, marketed as Ambien or Stilnox, is a nonbenzodiazepine used for the short-term treatment of insomnia.
1. J.H. Lewis and J.H. Vine. “A Simple and Rapid Method for the Identification of Zolpidem Carboxylic Acid in Urine.” Journal of Analytical Toxicology, Vol. 31, May 2007.