Optimize drug therapy and monitor patient adherence.
Quantitative Liquid Chromatography-Tandem Mass Spectrometry
Timing of specimen collection: Pre-dose (trough) draw - At steady state concentration.
Plain red. Also acceptable: Lavender (K2 or K3EDTA) or pink (K2EDTA).
Separate serum or plasma from cells within 2 hours of collection. Transfer 1 mL serum or plasma to an ARUP Standard Transport Tube. (Min: 0.5 mL)
Whole blood. Gel separator tubes, light blue (citrate), or yellow (SPS or ACD solution).
After separation from cells: Ambient: 5 weeks; Refrigerated: 2 months; Frozen: 2 months
|Therapeutic Range||Not well established|
|Toxic Level||Total Clozapine and Metabolites: Greater than or equal to 1500 ng/mL|
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, non-responsiveness 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.
Laboratory Developed Test (LDT)
|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|