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Toxicological screening , Benzodiazepines, zolpidem and zopiclone

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  231

2026-10-17

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Toxicological screening

Benzodiazepines, zolpidem and zopiclone

Benzodiazepine tranquillisers are prescribed widely and therefore occur more frequently than any other type of drug in overdose cases. The effects of these drugs in overdose are usually mild, although they may have a synergistic effect when taken with alcohol or other drugs. The anticonvulsive benzodiazepine clonazepam (Rivotril) is also used to detoxify patients with very severe (other) benzodiazepine dependence. Although these drugs do not seem to cause lethal intoxications, reports of deaths from benzodiazepines have been published, most of which refer to elderly people or case of combined over dose of flunitrazepam and opiates. The hypnotic flunitrazepam can also cause a paradoxical effect, which is noticed by hooligans using this benzodiazepine. Over 30 benzodiazepines are available; some of these are both the parent compound and a metabolite of other benzodiazepines. The intrinsic activity varies enormously from one to the other. For example, alprazolam has a therapeutic effect at a serum concentration of 1 lg/L, whereas oxazepam becomes active on average at 1000 lg/L. This phenomenon makes comprehensive screening for the group very difficult. Many of the metabolites (including some glucuronides) are also active. In patients with renal failure the metabolite midazolam glucuronide can still be active even if the parent compound and its hydroxy metabolite are no longer measurable. Several immunoassays are available to screen for the benzodiazepine group in urine. However, in most of these the antibodies do not react with the glucuronides and, therefore, prior enzyme hydrolysis of the urine is required. The hypnotics zolpidem and zopiclone have similar dynamic and toxic activity to the benzo diazepines. Although these are not benzodiazepines, they have a high cross-reactivity with most benzodiazepine immunoassays.