Quetiapine cross-reactivity among three tricyclic antidepressant immunoassays

J Toxicol Clin Toxicol. 2003;41(2):105-8. doi: 10.1081/clt-120019122.

Abstract

Quetiapine is an atypical antipsychotic agent with structural similarities to the tricyclic antidepressants (TCA). We report a case of quetiapine overdose that was initially clinically similar to that of a TCA overdose and caused a false-positive TCA immunoassay. We then analyzed three common TCA immunoassays [Microgenics (formerly Diagnostic Reagents, Inc.) Tricyclics Serum Tox EIA Assay, Syva RapidTest d.a.u., and Biosite Triage Panel for Drugs of Abuse] with quetiapine in solution as well as urine from both an overdose patient and a therapeutic patient. There was significant variation of the cutoff of false-positivity in all three immunoassays. Both the Syva and Microgenics immunoassays tested positive in both the overdose and therapeutic samples and were positive at urine levels of 100 microg/mL and 10 microg/mL, respectively. The Triage immunoassay was negative in solutions up to 1000 microg/mL and negative in both the therapeutic and overdose urine samples. Quetiapine may cause false-positive TCA immunoassay with both therapeutic use and in overdose. Significant variation exists between immunoassays to detect quetiapine as a false-positive test.

Publication types

  • Case Reports

MeSH terms

  • Adult
  • Antibody Specificity
  • Antidepressive Agents, Tricyclic / chemistry
  • Antidepressive Agents, Tricyclic / immunology*
  • Antidepressive Agents, Tricyclic / urine
  • Antipsychotic Agents / immunology*
  • Antipsychotic Agents / poisoning
  • Antipsychotic Agents / urine
  • Chromatography, Gas
  • Cross Reactions
  • Dibenzothiazepines / immunology*
  • Dibenzothiazepines / poisoning
  • Dibenzothiazepines / urine
  • Drug Overdose
  • Electrocardiography
  • False Positive Reactions
  • Female
  • Humans
  • Immunoassay
  • Long QT Syndrome / chemically induced
  • Quetiapine Fumarate
  • Suicide, Attempted

Substances

  • Antidepressive Agents, Tricyclic
  • Antipsychotic Agents
  • Dibenzothiazepines
  • Quetiapine Fumarate