Diazepam, Serum or Plasma

Serum or plasma

1 mL

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.

Diazepam is effective in the management of generalized anxiety disorder and panic disorder in appropriately selected patients. Its use prior to endoscopy or cardioversion relieves anxiety and diminishes the patient's recall of the procedure. Preoperative use relieves anxiety and tension and may provide anterograde amnesia. Additional uses include the treatment of skeletal muscle spasms due to inflammation or trauma, spasticity (eg, multiple sclerosis, cerebral palsy, paraplegia, stiff-man syndrome), seizure disorders (eg, status epilepticus, febrile seizures), and alleviation of abstinence symptoms during alcohol withdrawal.

This test was developed and its performance characteristics determined by Labcorp. It has not been cleared or approved by the Food and Drug Administration.

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

Therapeutic: diazepam + nordiazepam: 0.2−2.5 μg/mL

Diazepam is a muscle relaxant and antianxiety drug. Peak blood levels are achieved within an hour after oral dose. Half-life in adults is 21 to 37 hours. The major metabolite (nordiazepam) has a half-life in adults of 50 to 99 hours. It is the major metabolite also of clorazepate and prazepam. Minor active metabolites of diazepam are temazepam (3-hydroxydiazepam) and oxazepam (3-hydroxy-N-diazepam).^1,2 Diazepam may exhibit synergism with barbiturates, tricyclic antidepressants, and amine oxidase inhibitors. Toxicity may be additive with other central nervous system depressants, and ethanol enhances the absorption of diazepam itself. Many cases of overdose are seen but few fatalities result from use of this drug alone. A frequent finding is a combination of this drug and ethanol.