MedEx Multi-Drug 5 Drugs Rapid Test Panel (Urine) Mechanism of Action

Principle (For DOA tests excluding Alcohol): During testing, a urine specimen migrates upward by capillary action. A drug, if present in the urine specimen below its cut-off concentration, will not saturate the binding sites of its specific antibody. The antibody will then react with the drug-protein conjugate and a visible colored line will show up in the test region of the specific drug dipstick. The presence of drug above the cut-off concentration will saturate all the binding sites of the antibody. Therefore, the colored line will not form in the test region.
A drug-positive urine specimen will not generate a colored line in the specific test region of the dipstick because of drug competition, while a drug-negative urine specimen will generate a line in the test region because of the absence of drug competition.
To serve as a procedural control, a colored line will always appear at the control region, indicating that proper volume of specimen has been added and membrane wicking has occurred.
Reagents (For DOA tests excluding Alcohol): Each test line contains anti-drug mouse monoclonal antibody and corresponding drug-protein conjugates. The control line contains goat anti-rabbit IgG polyclonal antibodies and rabbit IgG.
Performance Characteristics: Accuracy: (See Table 1.)

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Precision: A study was conducted at three hospitals using three different lots of product to demonstrate the within-run, between-run and between-operator precision. An identical card of coded specimens, containing drugs at concentrations of negative, 50%, and 25% cut-off level, was labeled, blinded and tested at each site. The results gained ≥75% accuracy in ±25% cut-off level specimen and 100% accuracy in negative and ±50% cut-off level specimen.
Analytical Sensitivity: A drug-free urine pool was spiked with drugs at the listed concentrations. The results are summarized as follows: (See Table 2.)

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Analytical Specificity: The following table lists the concentrations of compounds (ng/mL) that are detected as positive in urine by the Multi-Drug Rapid Test at 5 minutes. (See Table 3.)

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Effect of Urinary Specific Gravity: Fifteen (15) urine samples of normal, high, and low specific gravity ranges (1.005-1.045) were spiked with drugs at 50% below and 50% above cut-off levels, respectively. The Multi-Drug Rapid Test was tested in duplicate using fifteen drug-free urine and spiked urine samples. The results demonstrate that varying ranges of urinary specific gravity do not affect the test results.
Effect of Urinary pH: The pH of an aliquoted negative urine pool was adjusted to a pH range of 5 to 9 in 1 pH unit increments and spiked with drugs at 50% below and 50% above cut-off levels. The spiked, pH-adjusted urine was tested with the Multi-Drug Rapid Test. The results demonstrate that varying ranges of pH do not interfere with the performance of the test.
Cross-Reactivity: A study was conducted to determine the cross-reactivity of the test with compounds in either drug-free urine or drug-positive urine containing previously mentioned related calibrator substances. The following compounds show no cross-reactivity when tested with the Multi-Drug Rapid Test at aconcentration of 100 μg/mL. (See Table 4.)

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