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.
