Forensic Testing for Benzodiazepines - Chromatography Can Help
Sep 19 2019 Read 424 Times
Benzodiazepines (BZDs) are a commonly prescribed sedative - but, like many other prescription medicines, BZDs are misused, both recreationally and criminally. And like many drugs, they have to be tested for both clinically and forensically. A recent paper published in the Journal of Forensic Science & Criminology reports on work carried out by researchers in India to develop:
‘universal, rapid, precise and sensitive TLC, HPLC and GC-MS methods for the separation and detection of alprazolam, chlordiazepoxide, clonazepam, clobazam, diazepam, flurazepam, nitrazepam and midazolam drugs in bulk powder and in pharmaceutical dosage form as well as in confiscated materials.’
Let’s take a closer look at BZDs, see how they might be misused and see how chromatography could help forensic testing for BZD use and abuse.
BZD and GABA - working together
Benzodiazepines are a sedative, but they are also used for a few other treatments including epilepsy and treating alcohol withdrawal. As a sedative, BZDs can be short-acting - temazepam or Rohypnol - for use as a sleeping tablet, or long-acting - diazepam or lorazepam - for managing anxiety.
BZDs work by acting on the central nervous system where they can selectively occupy GABA-A receptors in the brain. The brain has several types of GABA receptors that respond to the neurotransmitter GABA (gamma-aminobutyric acid). GABA is the main inhibitory neurotransmitter in the brain and regulates movement control, sight and anxiety amongst other functions.
When a patient takes a BZD, it enhances the response to GABA. It does this by opening GABA activated channels allowing chloride ions to enter the neuron. The neuron becomes negatively charged and resistant to excitation. Helping to control a patient’s anxiety or reducing activity to help sedation.
Sedative with a dark side
But as well as their use as a prescription medicine, BZDs can also be used as a recreational drug and to help commit crime - particularly drug facilitated sexual assaults. In many cases, it can be several days before an assault victim reports the incident. In recent years there has also been a reported increase in the use of BZDs as a recreational drug. Consequently, it is important to have methods in place for either clinical or forensic analysis of samples.
The team of researchers behind the paper referenced above recognised the importance of chromatography in analysing samples: ‘Because chromatography techniques are so versatile and can be used to determine so many different compounds, the technique is particularly well suited to the demands of a forensic laboratory.’ The role of chromatography in regulatory labs is discussed in the article, Monitoring drugs in sport testing: an insight of current trends and recent findings from the Drug Control Centre, the UK’s Anti-Doping Laboratory. The methods developed by the team offer the simultaneous screening and identification of most BZDs commonly seen in forensic and clinical cases in India.
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