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Design VerificationHumaDrug C 3 Specificity, sensitivity and agreement .2 HumaDrug CANNABINOIDS (THC) has been designed as a rapid 1-step test for the qualitative detection of cannabinoids (THC) in human urine. The test is based on a competitive immunochromatographic technique, featuring immobilized drug and dye-labeled anti-THC antibodies. If cannabinoids are present in the urine sample drug molecules compete with the immobilized drug for limited amounts of dye-labeled anti-drug antibodies.
Above a threshold concentration only one coloured line will appear on the membrane (positive result). Below that concentration two coloured lines will be observed (negative result). The test has been adjusted to the suggested screening cut-off for positive specimens set by SAMSHA (Substance Abuse and Mental Health Services Administration, USA). HumaDrug CANNABINOIDS comes in a convenient package, consisting of test cassettes and disposable dropper pipettes. The urine sample is pipetted onto the test cassettes disposable plastic dropper pipettes.
2 Sensitivity and dynamic range Urine drug controls (Bio-Rad, J&S, others) are employed for testing of sensitivity and dynamic range.
The respective drug concentrations have been standardized by the manufacturer.
Standard dilutions are prepared from either urine controls or pure substances (i.e. Sigma, #N5642) by dilution with phosphate buffered saline to approx. the following concentrations:Table 1: Standard test concentrations (11-nor-∆8-tetrahydrocannabinol-9-carboxylic acid) All concentrations were tested in 10-fold determination. Strong test and control lines appeared with negative urines and zero-standards. In the presence of THC at concentrations of 25 ng/ml a strong control line came up after 5 minutes incubation, accompanied by a clearly visible test line. At 50 ng/ml, the “new” SAMSHA cut-off value, a strong control line was observed, sometimes accompanied by a faint test line. At 75 ng/ml only a strong control line appeared within the incubation period of 5 minutes. The test devices must not be interpreted after 10 minutes as in some cases after that time a faint test line may appear even with weak positive samples, due to unspecific reactions on the membrane. Prozone phenomenon will not occur with such a competitive test format and even extremely high concentrations of the analyte will not produce false negative results (two lines).
3 Specificity, sensitivity and agreement The specificity and sensitivity of HumaDrug CANNABINOIDS have been evaluated by method comparison against the GC/MS reference method. 300 urine specimens have been employed in the comparison.
Design Verification and Product Data for HumaDrug CANNABINOIDS From this comparison the relative diagnostic sensitivity and specificity have been calculated according: A number of potentially interfering substances have been added at a concentration of 100 µg/ml to negative and positive urine specimens, respectively.).
Table 2: Potentially interfering substances Design Verification and Product Data for HumaDrug CANNABINOIDS Conclusion: At the tested concentration of 100 µg/ml none of the substances listed in table 2 interfered with Cross-reactivities of HumaDrug CANNABINOIDS have been studied by adding potentially cross-reacting substances in various concentrations to negative urine samples. The following substances were found to cross react at levels Conclusion: Cannabinol, ∆9-THC and ∆8-THC produced positive results only at very high concentrations.
Therefore, it exists no cross-reactivity with these substances at lower concentrations.
4 Reproducibility Day-to-day and lot-to-lot reproducibility was evaluated, employing the standard concentrations as given in 2.1 (up to 75 ng/ml).
4.1 Within-day reproducibility Within 10 days the results at 0 and 25 ng/ml were consistenly negative. At 50 ng/ml consistenly borderline results have been obtained (very faint test line), and at 75 ng/ml consistently positive results appeared (no visible test line). In no case discrepant results were found.
Design Verification and Product Data for HumaDrug CANNABINOIDS Similarly, the reproducibility between three independent lots was tested with the same concentrations as mentioned above. Each concentration was tested with each lot in 10-fold determinations. All results were fully consistent.
Conclusion: HumaDrug CANNABINOIDS has shown to produce excellently reproducible results from day to day The stability of HumaDrug CANNABINOIDS has been demonstrated on real time stability studies and additional For real time studies, test devices have been stored for a period of up to 24 months at 25°C and 60% relative For temperature stress studies the test devices have been stored for up to 73 days at 45°C and 60% relative Standard concentrations according to 2.1 were employed and each concentration was tested in double. The results are presented in tables 3 and 4 below.
Table 3: Real time stability (mean of double determination) Table 4: Accelerated stress stability (mean of double determination) Conclusion: According to the results from both real time as well as accelerated temperature stress HumaDrug CANNABINOIDS has been shown to be at least stable for 24 months when stored at 25°C.
Design Verification and Product Data for HumaDrug CANNABINOIDS

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