Preferred Sample Type

Benzodiazepine Quantiation (Diazepam, Nordiazepam, Temazepam, Oxazepam)

Suitable Specimen Types

  • Serum
  • EDTA Plasma
  • Li Hep Plasma
A minimum of 100 ┬Ál of plasma/serum is required.

Specimen Transport

First class post

Sample Processing in Laboratory

Place sample in toxicology rack.

Sample Preparation

None required

Turnaround Time

3 days.

Sample Stability

Keep refrigerated. 4 degrees.

Benzodiazepine Quantiation (Diazepam, Nordiazepam, Temazepam, Oxazepam)

General Information

A benzodiazepine (sometimes colloquially "benzo") is a psychoactive drug whose core chemical structure is the fusion of a benzene ring and a diazepine ring.  Diazepam (valium) is frequently employed as an anti-anxiety agent, muscle relaxant or anticonvulsant. It is administered orally or by intramuscular or intravenous injection in single adult doses of 2 - 20 mg and up to 40 mg daily. Diazepam undergoes N-demethylation to nordiazepam, a metabolite at least as active as its parent. Both of these compounds are converted to 3-hydroxy derivatives, temazepam and oxazepam. Both oxazepam (Serax) and temazepam (methyloxazepam, Normison, Restoril) are prescribed as pharmacological agents in their own right.

Adverse effects of benzodiazepine therapy include sedation, confusion and incoordination. Chronic usage may cause physical dependence, and grand mal seizures can occur upon withdrawl.

Please note, this assay is for the quantitative determination of four benzodiazepines (diazepam, nordiazepam, temazepam and oxazepam) in blood. Benzodiazepines (diazepam, nordiazepam, temazepam, oxazepam, flunitrazepam, lorazepam, midazolam & nitrazepam) use may also be detected via our urinary Drugs of Abuse Screen by LC-MS/MS.


Patient Preparation

No patient preperation required.


Diazepam, Nordiazepam, Temazepam and Oxazepam measured by LC-MS/MS


Reference Range

Diazepam: Toxicity associated with concentrations > 3 mg/L.

Nordiazepam: Toxicity associated with concentrations >  1.5 mg/L.

Oxazepam: Toxicity associated with concentrations > 2 mg/L.

Temazepam: Toxicity associated with concentrations > 2 mg/L.
(Schulz et al. Critical Care 2012, 16:R136).

Please contact the laboratory if benzodiazepine measurement is required for therapeutic monitoring purposes.


  • EQA Scheme?: Yes

The laboratories at Heartlands Hospital, Good Hope Hospital and Solihull Hospital form part of the services provided by University Hospitals Birmingham and are UKAS (United Kingdom Accreditation Service) accredited to the ISO 15189:2012 standard. For a list of accredited tests and other information please visit the UKAS website using the following link:

  • Heartlands, Good Hope and Solihull Hospital pathology laboratories are a UKAS accredited medical laboratory No.8217
  • United Kingdom Health Security Agency laboratory is a UKAS accredited medical laboratory No.8213

Tests not appearing on the UKAS Schedule of Accreditation currently remain outside of our scope of accreditation. However, these tests have been validated to the same high standard as accredited tests and are performed by the same trained and competent staff.

For further test information, please visit the test database:

Protection of personal information - Laboratory Medicine comply with the Trust Data Protection policy and have procedures in place to allow the Directorate and its employees to comply with the Data Protection act  1998 and associated best practice and guidance.

For further information contact Louise Fallon, Quality Manager, 0121 424 1235