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Ranitidine interference with the monoclonal EMIT d.a.u. amphetamine/methamphetamine immunoassay
1Medical College of Virginia Hospital, Department of Pathology, Virginia Commonwealth University, Richmond 23298-0597.
Journal of Analytical Toxicology
|March 1, 1991
Summary
Ranitidine can cause false positive results in monoclonal EMIT d.a.u. amphetamine/methamphetamine immunoassays (ME). This interference, observed at ranitidine concentrations above 91 mg/L, did not affect polyclonal assays.
Area of Science:
- Clinical Chemistry
- Forensic Toxicology
- Pharmaceutical Analysis
Background:
- Ranitidine is a widely prescribed medication.
- Urine drug screening is crucial for patient management and legal purposes.
- Immunoassays are common methods for drug detection but can be subject to interference.
Purpose of the Study:
- To investigate the potential interference of ranitidine with a specific monoclonal immunoassay for amphetamine and methamphetamine.
- To determine the concentration threshold at which ranitidine causes false positive results.
Main Methods:
- Urine specimens from patients taking ranitidine were analyzed.
- Ranitidine concentrations were measured using high-pressure liquid chromatography (HPLC).
- Urine samples were tested using the monoclonal EMIT d.a.u. amphetamine/methamphetamine immunoassay (ME).
Main Results:
- Ranitidine was detected in patient urine at concentrations ranging from 7-271 mg/L.
- False positive ME results were observed in samples with ranitidine concentrations exceeding 91 mg/L.
- 12 out of 63 patient samples yielded false positive ME results, primarily in early voids post-ingestion.
Conclusions:
- Ranitidine can interfere with the monoclonal EMIT d.a.u. amphetamine/methamphetamine immunoassay, leading to false positives.
- The interference is concentration-dependent, occurring above 91 mg/L.
- Polyclonal amphetamine assays (EMIT d.a.u. and TDx) were not affected by ranitidine interference.