Clonazepam

TEST: 071712
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CPT: 80299
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Synonyms

  • Klonopin®

Special Instructions

Co-administration of Lorazepam can potentially cause a falsely lower Clonazepam result in this method.

Expected Turnaround Time

2 - 4 days

Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.

Related Documents

Specimen Requirements

Specimen

Serum or plasma

Volume

4 mL

Minimum Volume

1.1 mL

Container

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.

Collection

Transfer separated serum or plasma to a plastic transport tube. Collect specimen immediately prior to next dose unless specified otherwise.

Storage Instructions

Refrigerate.

Stability Requirements

Temperature

Period

Room temperature

14 days

Refrigerated

14 days

Frozen

14 days

Causes for Rejection

Gel-barrier tube

Test Details

Use

Evaluate toxicity; monitor therapeutic levels

Limitations

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

Methodology

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

Reference Interval

Therapeutic: 20−70 ng/mL

Critical Value

Potentially toxic: >80 ng/mL

Additional Information

The drug is used in the treatment of petit mal variant (Lennox-Gastaut), akinetic seizures and myoclonic seizures. Serum peak levels occur approximately two hours after oral administration. The apparent half-life after a single oral dose is 20 to 40 hours. Active metabolites have longer half-lives than the parent drug. Half-lives are increased in the elderly. Therapeutic effect is not well correlated with serum levels. Effect of CNS depressants may be augmented by concomitant use of this agent. This drug is used as an anticonvulsant. It is useful in reducing tardive dyskinesia.1

Footnotes

1. Thaker GK, Nguyen JA, Strauss ME, Jacobson R, Kaup BA, Tamminga CA. Clonazepam treatment of tardive dyskinesia: A practical GABAmimetic strategy. Am J Psychiatry. 1990 Apr; 147(4):445-451. 1969244

References

Drug Information Handbook. 24th ed. Hudson, OH: Wolters Kluwer Clinical Drug Information, Inc; 2015; 478-480.

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
071712 Clonazepam (Klonopin(R)),Serum 3494-2 071712 Clonazepam (Klonopin(R)),Serum ng/mL 3494-2

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