Lab Test

Nefazodone Level

Serzone , NMS #3145, Order as a Miscellaneous Sendout.

Specimen Collection Criteria

Collect (preferred specimen): One plain Red-top tube.
Also acceptable: One Lavender-top EDTA tube or 5.0 mL random urine in a sterile collection container. (Min: 0.7 mL)

Do not use Serum Separator Tubes.
Time of Collection:
 Trough, just prior to the next dose. 

Physician Office/Drawsite Specimen Preparation

Centrifuge to separate serum or plasma from cells. Transfer serum or plasma to a plastic transport tube and refrigerate (2-8°C or 36-46°F). Maintain urine specimen refrigerated.

Preparation for Courier Transport

Transport: 1.0 mL serum, plasma, or urine, refrigerated (2-8°C or 36-46°F). (Min: 0.2 mL)

Rejection Criteria

  • Specimens collected in SST tubes.
  • Specimens not collected and processed as indicated.


Results available in 3-10 days.

Reference Range

By report.

Test Methodology

High Performance Liquid Chromatography (HPLC) / Tandem Mass Spectrometry (LC-MS/MS).


Nefazodone (Serzone) was recently approved for the treatment of depression. Nefazodone appears to have fewer incidences of nervousness, anxiety, tremor and possible sexual dysfunctions than many orther antidepressant drugs.

Nefazodone is rapidly and completely absorbed following oral administration with extensive first pass metabolism. Peak levels are typically reached at approximately 1.2 hours with a half-life of 2 - 4 hours. The pharmacokinetics are non-linear with markedly increased plasma levels seen with increases in dose and over time. Steady state plasma levels are attained within 4 - 5 days (2).

Clinical Utility

This assay is used for the therapeutic monitoring and toxicity assessment of nefazodone.


  1. Ferry N., et. al., Influence of Hepatic Impairment on the Pharmacokinetics of Nefazodone and Two of its Metabolites After Single and Multiple Oral Doses, Fundam. Clin.Pharmacol., 8 (1994) 463-473.
  2. Olin B.R. (editor-in-chief), Drug Facts and Comparisons Monthly Update, Facts and Comparisons, Inc., St. Louis, MO, March 1995, pp. 263Y-264C.

CPT Code


Test Codes

NMS #3145, Order as a Miscellaneous Sendout.

Last Updated


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This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.