Urinary Detection Times and Excretion Patterns of Flunitrazepam and its Metabolites After A Single Oral Dose

Abstract

We investigated the excretion profiles of flunitrazepam metabolites in urine after a single dose. Sixteen volunteers received either 0.5 or 2.0 mg flunitrazepam. Urine samples were collected after 2, 4, 6, 8, 12, 24, 48, 72, 96, 120, 240, and 336 h. Samples were screened using CEDIA (300 microg/L cutoff) and quantitated using liquid chromatography-tandem mass spectrometry. The cutoff was 0.5 microg/L for flunitrazepam, N-desmethylflunitrazepam, 7-aminoflunitrazepam, 7-aminodesmethylflunitrazepam, 7-acetamidoflunitrazepam, and 7-acetamidodesmethylflunitrazepam. None of the subjects receiving 0.5 mg were screened positive, and only 23 of 102 samples from the subjects given 2.0 mg were positive with CEDIA. The predominant metabolites were 7-aminoflunitrazepam and 7-aminodesmethylflunitrazepam. For all subjects given the low dose, 7-aminoflunitrazepam was detected up to 120 h, and for two subjects for more than 240 h. Seven subjects given the high dose were positive up to 240 h for 7-aminoflunitrazepam. We conclude that the ratio 7-aminodesmethylflunitrazepam to 7-aminoflunitrazepam increased with time, independent of dose, and may be used to estimate the time of intake. For some low-dose subjects, the metabolite concentrations in the early samples were low and a chromatographic method may fail to detect the intake. We think laboratories should consider this when advising police and hospitals about sampling as well as when they set up strategies for analysis.

Flunitrazepam Product Detected in the Stomach of an Autopsy Case Buried Under the Ground for Two Years

“…The recent minimum limit of detection of FNZ and 7-amino FNZ in urine was lower than those of the present analysis by the use of solid column extraction and LC-MS-MS system [6]. If their methods could be examined in the present case, the sensitivity in the samples might be improved.…”

“…FNZ is quickly absorbed after oral administration by the small intestine within 20-30 min [6], peaked plasma concentrations in about 1h with an elimination half-life of 13-19 h [6]. The clinical effect varies between 4 and 8 h depending on the dosage given [6].…”

“…The clinical effect varies between 4 and 8 h depending on the dosage given [6]. FNZ is excreted in the urine almost entirely as metabolites, both free and conjugated with glucuronic acid, with less than 1% as unchanged drug [2].…”

“…FNZ is excreted in the urine almost entirely as metabolites, both free and conjugated with glucuronic acid, with less than 1% as unchanged drug [2]. Seven subjects given the 2 mg of FNZ were positive up to 240 h for 7-amino FNZ in their urine [6].…”

Development of a Surface-Enhanced Raman Spectroscopy Method for the Detection of Benzodiazepines in Urine

“…The screening process is further complicated due to the metabolism process as described previously, which gives rise to multiple metabolites. 13,14,15,9,12,16,17,18,19 …”