N-desmethyldiazepam: a new metabolite of chlordiazepoxide in man

Clin Pharmacol Ther. 1976 Oct;20(4):450-7. doi: 10.1002/cpt1976204450.


Following administration of chlordiazepoxide HCl to man, N-desmethyldiazepam, a known metabolite of diazepam (Valium), was identified in plasma. The metabolite was identified on the basis of its thin-layer chromatographic (TLC) mobility, electron-capture gas-chromatographic (EC-GC) retention time, and mass spectrum relative to authentic N-desmethyldiazepam. Plasma levels of N-desmethyldiazepam in subjects receiving both single and chronic doses of chlordiazepoxide were determined by an EC-GC method with a limit of sensitivity of 10 ng/ml using 2-ml samples and by a radioimmunoassay procedure which had a limit of sensitivity of 20 ng/ml using a 0.1-ml sample. Both assay methods gave good agreement for the levels of N-desmethyldiazepam. In subjects receiving a single 30-mg oral or intravenous dose of chlordiazepoxide, measurable levels of N-desmethyldiazepam in plasma (10 to 60 ng/ml) were obtained 24 to 72 hr after administration. In 5 subjects receiving 10 mg of chlordiazepoxide three times a day, steady-state levels of N-desmethyldiazepam in plasma were reached after about 1 wk of administration. The mean maximum and minimum steady-state levels of N-desmethyldiazepam were 260 and 220 ng/ml of plasma, respectively. Similar steady-state levels were observed on treatment with 30 mg of chlordiazepoxide over 24 hr.

MeSH terms

  • Animals
  • Chlordiazepoxide / metabolism*
  • Chromatography, Gas
  • Diazepam / analogs & derivatives*
  • Humans
  • Nordazepam / blood*
  • Nordazepam / isolation & purification
  • Rabbits / immunology
  • Radioimmunoassay
  • Time Factors


  • Nordazepam
  • Chlordiazepoxide
  • Diazepam