CPT: 80346
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Test Details


  • Librium®

Test Includes

Chlordiazepoxide and metabolites; demoxepam; N-desmethylchlordiazepoxide; N-desmethyldiazepam


Evaluate toxicity; monitor therapeutic levels


Liquid chromatography/tandem mass spectrometry (LC/MS-MS)

Additional Information

This drug is commonly used in suicide attempts. Chlordiazepoxide is slowly absorbed and may take several hours to reach a peak plasma level. Distribution after intramuscular administration is poor. Drug half-life in blood ranges from 16 to 27 hours. The drug is highly (90%) protein bound. Overdosage with the benzodiazepines is frequent, but serious sequelae are rare; however, there is an additive effect when used with other CNS depressants (eg, ethanol). If a patient is comatose after a drug ingestion, chlordiazepoxide alone is not a sufficient explanation. Metabolism results in the production of four active metabolites. This drug is used as an antianxiety agent for treatment of withdrawal symptoms of acute alcoholism.

Half-life elimination: 6.9 to 28 hours

Time to peak: 0.5 to 2 hours

Specimen Requirements


Serum or plasma


1 mL

Minimum Volume

0.4 mL


Red-top tube, lavender-top (EDTA) tube, or green-top (heparin) tube. Do not use a gel-barrier tube. The use of gel-barrier tubes is not recommended due to slow absorption of the drug by the gel. Depending on the specimen volume and storage time, the decrease in drug level due to absorption may be clinically significant.


Transfer separated serum or plasma to a plastic transport tube. Oral: peak: four hours; trough: immediately prior to next dose.

Storage Instructions


Causes for Rejection

Gel-barrier tube

Clinical Information


American Medical Association. Division of Drugs and Toxicology. Drug Evaluations Subscription. Chicago, Ill: AMA; Summer 1991.
Drug Information Handbook. 24th ed. Hudson, OH: Wolters Kluwer Clinical Drug Information, Inc; 2015; 422.
Hiemke C, Baumann P, Bergemann N, Conca A, et al. AAGNP consensus guidelines for therapeutic drug monitoring in psychiatry: Update 2011. Pharmacopsychiatry. 2011 Sep; 44(6):195-235. 22053351


Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
007682 Chlordiazepoxide, Serum 019661 Chlordiazepoxide, S ug/mL 3457-9
007682 Chlordiazepoxide, Serum 019679 Norchlordiazepoxide ug/mL 9776-6
007682 Chlordiazepoxide, Serum 019687 Nordiazepam, Serum ug/mL 3537-8
007682 Chlordiazepoxide, Serum 019689 Sum of Metabolites ug/mL 33060-5

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