Chromatographic Screening for Zopiclone and Metabolites in Urine Using Liquid Chromatography and Liquid Chromatography–Mass Spectrometry Techniques

Abstract

Zopiclone is a benzodiazepine-like hypnotic that was believed not to have any abuse potential. Nevertheless, during the past few years there have been an increasing number of reports on the abuse and misuse of zopiclone. Despite this, methods for screening analysis in urine are lacking. To investigate whether UV detection would be possible to use for this purpose, a liquid chromatography method with ultraviolet detection for analyzing zopiclone and its urinary metabolites was developed, with liquid chromatography-mass spectrometry for confirmation. The method was used for analyzing samples from subjects receiving methadone. The limits of detection were approximately 100 ng/mL in control urine samples and 500 ng/mL in urine samples from subjects receiving methadone. However, due to the high background in these patients' urine, a single therapeutic dose was impossible to detect.

Stability tests of zopiclone in whole blood

“…Standard solutions should be prepared in acetonitrile and extraction must be done at neutral pH to ensure stability [10,11]. Several analytical methods have been developed for the quantification of zopiclone in whole blood, plasma and/or urine [9,[12][13][14][15][16][17][18][19][20][21][22], its metabolites N-desmethylzopiclone and/or N-oxide-zopiclone [12,14,[22][23][24], its (À) and (+)-enantiomers [11,[25][26][27], and its degradation product 2-amino-5-chloropyridine [17,28].…”

Quantitation of zopiclone and desmethylzopiclone in human plasma by high-performance liquid chromatography using fluorescence detection

“…Several methods have been reported to detect zopiclone and its metabolite desmethylzopiclone in urine (Fernandez et al, 1993;Hempel and Blaschke, 1996;Daenens, 1994, 1996;Nordgren et al, 2002), as the metabolites are not been detected in plasma (Gaillot et al, 1983;Houghton et al, 1985;LeLiboux et al, 1987). Recently, Gebauer and Alderman (2002) detected desmethylzopiclone in an overdose sample, but not in plasma samples obtained from patients on therapeutic doses of zopiclone.…”

Screening and confirmatory method for benzodiazepines and hypnotics in oral fluid by LC-MS/MS

“…Precision at 2 ng/mL were lower than 8% in all cases except zopiclone (34%). The higher CV for zopiclone is probably due to the instability of the drug in solutions, as mentioned previously [11]. Extraction recovery, measured at the same concentrations was >80%, making it suitable for a screening procedure.…”