Effective December 14, 2023: This test is temporarily unavailable due to analytic issues. The downtime is expected to be >30 days. Order FCLMS as an alternate. See test notification here.
Assessing patient compliance
Monitoring for appropriate therapeutic level
Assessing clonazepam toxicity
Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
Klonopin (Clonazepam)
Rivotril (Clonazepam)
Clonazepam
7-Aminoclonazepam
Serum Red
Collection Container/Tube: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 1.2 mL
Collection Instructions:
1. Draw blood immediately before next scheduled dose (minimum 12 hours after last dose).
2. Within 2 hours of collection, the specimen must be centrifuged and the serum aliquoted into a plastic vial.
If not ordering electronically, complete, print, and send a Therapeutics Test Request (T831) with the specimen.
0.6 mL
Gross hemolysis | OK |
Gross lipemia | OK |
Gross icterus | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum Red | Refrigerated (preferred) | 14 days | |
Frozen | 28 days | ||
Ambient | 72 hours |
Assessing patient compliance
Monitoring for appropriate therapeutic level
Assessing clonazepam toxicity
Clonazepam (5 [2-chlorophenyl]-2, 3-dihydro-7-nitro-1, 4-benzodiazepin-2-one), a benzodiazepine is useful alone or as an adjunct in the treatment of certain seizures. In addition, it may be useful in patients with panic disorder and restless legs syndrome.
Clonazepam has no definite antiseizure and antipanic mechanism of action, although it is believed to be related to its capacity to enhance gamma-aminobutyric acid (GABA) activity, which is the major inhibitory neurotransmitter in the central nervous system. It is able to suppress the spike and wave discharges in absence seizures and decreases the frequency, duration, amplitude, and spread of discharge in minor motor seizures.
Clonazepam is highly protein bound (approximately 85%). It is extensively metabolized by hepatic cytochrome P450, family 3, subfamily A (CYP3A) to inactive metabolites and has a half-life of 30 to 40 hours.
Clonazepam
Anticonvulsant: 20-70 ng/mL
Anxiolytic: 4-80 ng/mL
Some individuals may show therapeutic response outside of these ranges or may display toxicity within the therapeutic range, thus interpretation should include clinical evaluation.
Note: Therapeutic ranges are for specimens collected at trough (ie, immediately before next scheduled dose). Levels may be elevated in non-trough specimens.
The therapeutic range varies depending on the indication.
Some individuals may respond well outside of these ranges or may display toxicity within the therapeutic range, and thus, interpretation should include clinical evaluation.
The possibility of toxicity is increased when levels exceed 100 ng/mL.
Specimens that are obtained from gel tubes must be removed from the gel within 2 hours.
Hiemke C, Baumann P, Bergemann N, et al: AGNP Consensus Guidelines for Therapeutic Drug Monitoring in Psychiatry: Update 2011. Pharmacopsychiatry. 2011;44(6):195-235
Clonazepam and 7-aminoclonazepam are extracted from serum using a liquid-liquid extraction technique. The organic layer is removed, dried, and reconstituted. Analysis is by liquid chromatography-tandem mass spectrometry.(Unpublished Mayo method)
Monday, Wednesday
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.
80299
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
CZPS | Clonazepam and 7-Aminoclonazepam, S | 104541-8 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
65044 | Clonazepam | 3494-2 |
41782 | 7-Aminoclonazepam | 28059-4 |
Change Type | Effective Date |
---|---|
Test Status - Test Down | 2023-12-14 |