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Stability of nitrobenzodiazepines in postmortem blood
1Victorian Institute of Forensic Medicine, Department of Forensic Medicine, Monash University, Southbank, Australia.
Journal of Forensic Sciences
|February 11, 1998
Summary
Nitrobenzodiazepines and their metabolites show instability in blood, degrading rapidly under various conditions. For accurate testing, preserve blood samples with sodium fluoride and store at -20°C, analyzing promptly.
Area of Science:
- Forensic Toxicology
- Analytical Chemistry
- Pharmacokinetics
Background:
- Benzodiazepines are widely prescribed, necessitating reliable analytical methods.
- Understanding the stability of nitrobenzodiazepines and their metabolites is crucial for accurate toxicological analysis.
Purpose of the Study:
- To assess the stability of three nitrobenzodiazepines (nitrazepam, clonazepam, flunitrazepam) and their 7-amino metabolites.
- To evaluate degradation in various blood matrices and storage conditions relevant to forensic and clinical settings.
Main Methods:
- Nitrobenzodiazepines and metabolites were incubated in sterile and contaminated blood, and water, at different temperatures (22°C, 37°C).
- Stability was assessed over time (up to 28 days) under various storage conditions, including refrigeration (-20°C, 4°C) and freeze-thaw cycles.
- Degradation was quantified using analytical techniques.
Main Results:
- Nitrazepam and clonazepam were stable in preserved blood at 22°C, but flunitrazepam showed 25% degradation.
- At 37°C, all three drugs degraded significantly (29-51%) within 9 hours.
- In contaminated blood, drugs degraded within 8 hours, converting to 7-amino metabolites, which also showed partial degradation.
- Nitrobenzodiazepines were stable in stored blood (-20°C, 4°C), but metabolites were unstable at -20°C (29% loss in 2 months) and 4°C (21% loss in 1 month).
Conclusions:
- Nitrobenzodiazepines and their 7-amino metabolites exhibit significant chemical and metabolic instability in blood.
- Optimal sample handling involves preservation with sodium fluoride, storage at -20°C, and prompt analysis within one week of collection to ensure accurate results.