Interference of selected clinical medicines on DRI® and TDx® immunoassays of morphine and methamphetamine in urine

S. G. Chang, C. S. Chien, H. M. Lee, C. Y. Chen

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Eleven commonly used antihistamines, nonsteroidal anti-inflammatory drugs, and vitamins were evaluated in vitro for potential interference with DRI® and TDx® immunoassay reagents for opiates and amphetamines. Mechanisms for the observed interference were also explored. DRI® reagents appear to be more susceptible to interference by the compounds studied. Regarding mechanistic aspects, tolmetin was found to be strongly absorbent at the detection wavelength (340 nm) causing a false negative response; diphenhydramine, pheniramine, and trimethobenzamide appeared to cause false positive interference through their affinity to the antibodies used in the DRI® reagents; while chlorpromazine was found to positively interfere with the assay through both cross reaction and UV absorption. Ascorbic acid, when in high concentrations (>2%, w/v), may inhibit the enzyme (G6PDH) activity and result in a false negative response.

Original languageEnglish
Pages (from-to)259-268
Number of pages10
JournalJournal of Food and Drug Analysis
Volume7
Issue number4
Publication statusPublished - 1999

Keywords

  • Immunoassay
  • In vitro
  • Interference
  • Methamphetamine
  • Morphine

ASJC Scopus subject areas

  • Food Science
  • Pharmacology

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