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Clozapine and Metabolites, Serum or Plasma, Quantitative
Ordering Recommendation
Optimize drug therapy and monitor patient adherence.
Methodology
Quantitative Liquid Chromatography-Tandem Mass Spectrometry
Performed
Mon-Sat
Reported
1-5 Days
New York DOH Approval Status
This test is New York DOH approved.
Specimen Required
Patient Preparation:
Timing of specimen collection: Predose(trough) draw - at steady -state concentration.
Collect:
Plain red. Also acceptable: Lavender (K2 or K3EDTA) or pink (K2EDTA).
Specimen Preparation:
Separate serum or plasma from cells within 2 hours of collection. Transfer 1 mL serum or plasma to a standard transport tube.(Min: 0.5 mL)
Storage/Transport Temperature:
Refrigerated.
Unacceptable Conditions:
Whole blood. Gel separator tubes, light blue (citrate), or yellow (SPS or ACD solution).
Remarks:
Stability:
After separation from cells: Ambient: 24 hours; Refrigerated: 1 week; Frozen: 3 months
Reference Interval
Therapeutic Range
Not well established
Toxic Level
Total Clozapine and Metabolites: Greater than or equal to 1500 ng/mL
Interpretive Data
Therapeutic ranges are not well established. Clozapine is metabolized to norclozapine and clozapine-N-oxide. Clozapine concentrations between 100 and 700 ng/mL may correlate more with clinical response; however, nonresponsiveness may also occur within this range. For refractory schizophrenia, clozapine concentrations greater than 350 ng/mL are suggested to achieve a therapeutic response.
Toxicity: Adverse effects to clozapine therapy may include tachycardia, drowsiness, hypotension, and seizures.
Therapeutic and toxic ranges are not well established in children.
Note
CPT Code
80159
Components
Component Test Code
Component Chart Name
LOINC
2013458
Clozapine, S/P, Quant
6896-5
2013459
Norclozapine, S/P, Quant
10992-6
2013460
Clozapine-N-Oxide, S/P, Quant
85497-6
2013461
Total Clozapine and Metabolites
12375-2
Aliases
Clopine
Clozaril
Denzapine
FazaClo
Versacloz
Zaponex
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