Preferred Sample Type


Suitable Specimen Types

  • Serum
  • EDTA Plasma
  • Li Hep Plasma
A minimum of 500 µl 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.


General Information

Clobazam is a 1,5 benzodiazepine derivative utilized as a sedative, anticonvulsant and anti-anxeity agent in a number of European countries since 1978. Daily adult doses for adults may range from 20 – 60 mg.

Clobzam in overdosage causes moderate sedation with up to 300 mg has been ingested without serious toxic effects. However, genetic metabolic deficiences in the metabolism of clobazam may lead to accumulation of desmethylclobazam leading to symptoms such as severe ataxia and somnolence. 

Patient Preparation

For TDM, sample should be taken prior to dose. If toxicity is suspected, take sample at earliest opportunity


Clobazam measured by HPLC-DAD. Serum from gel tubes (yellow top) will NOT be analysed.

Reference Range

Therapeutic use of clobazam is associated with concentrations of up to 0.4 mg/L. (TIAFT reference blood level list of therapeutic and toxic substances, September 2004).


  • 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