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The AccuSign® MET test uses solid-phase immunoassay technol-
ogy for the qualitative detection of methamphetamine in humanurine. The test is based on the principle of the highly specificimmunochemical reactions between antigens and antibodies whichare used for the analysis of specific substances in biological fluids.
The test relies on the competition between the drug conjugates andthe drugs which may be present in the urine sample, for binding toantibodies. In the test procedure, a sample of urine is placed in the Sample well of the device and is allowed to migrate upward. If thedrug is present in the urine sample, it competes with the drug conjugate bound to the dye, for the limited antibodies immobilized on the membrane. If the level of the drug or its metabolite is above the cutoff level, the drug will saturate the antibodies, thus inhibit-ing the binding of the dye coated with drug conjugates to theantibodies on the membrane. This prevents the formation of a lineon the membrane. Therefore, a drug-positive urine sample will notgenerate a line at the specific drug position in the Result window,indicating a positive result from positive drug competition. A negative urine sample will generate a line at the specific drug position in the Result window, indicating a negative result from anabsence of competition with free drugs.
In addition to the Test line(s) that may appear in the Result window,a Control line is present to confirm the viability of the test. This The AccuSign® MET test is a simple, one-step, immunochromato-
Control line (validation line) should always appear if the test is graphic assay for the rapid, qualitative detection of methamphet- conducted properly. Polyclonal sheep anti-mouse IgG antibody is amine in urine above a cutoff concentration of 1000 ng/mL.
immobilized on the control line. The monoclonal antibody-dye The AccuSign® MET test provides only a preliminary analytical
conjugates that pass the line will be captured and produce a colored result. A more specific alternative chemical method must be used
line at the Control position (C). This works as a procedural control, in order to obtain a confirmed analytical result. Gas chromatog-
confirming that proper sample volume was used and the reagent raphy, mass spectrometry (GC/MS) is the preferred confirmatory
system at the Control line and the conjugate-color indicator worked method. Other chemical confirmatory methods are available.
properly. If insufficient sample volume is used, there may not be Clinical consideration and professional judgment should be
a Control line, indicating the test is invalid.
applied to any drug of abuse test result, particularly when
preliminary positive results are used.1
The AccuSign® MET test kit contains all the reagents necessary to
Methamphetamine is a potent sympathomimetic agent with thera- AccuSign® MET device. The test device contains a membrane
peutic applications. The drug can be taken orally, injected, or strip coated with anti-methamphetamine antibody and a dye inhaled. Acute higher doses lead to enhanced stimulation of the pad containing colloidal gold coated with drug-protein (from central nervous system and induce euphoria, alertness, reduced purified bovine protein source) conjugate.
appetite, and a sense of increased energy and power.2 Cardiovas- cular responses to methamphetamine include increased blood pressure and cardiac arrhythmias. More acute responses includeanxiety, paranoia, hallucinations, psychotic behavior, and eventu- For in vitro diagnostic use only.
The effects of methamphetamine generally last 2–4 hours, and thedrug has a half-life of 9–24 hours in the body. Methamphetamine Avoid cross contamination of urine samples by using a new is excreted in the urine primarily as amphetamine and oxidized and urine specimen container and dropper for each urine sample.
deaminated derivatives.2 However, 10–20% of methamphetamine The test kit does not contain any HIV or hepatitis infective is excreted unchanged. Thus, the presence of the parent compound in the urine indicates methamphetamine use. Methamphetamine is Urine specimens are potentially infectious. Proper handling generally detectable in the urine for 3–5 days, depending on urine and disposal methods should be established according to good CONTROL (VALIDATION) LINE (C).
The Control/Validation line indicates:1.
If the procedure was followed properly.
If no control line appears, the test is NOT VALID.
Repeat the test using a new device, and follow the Negative = Control line and Specific Drug line Positive = Control line only; No Specific Drug line The AccuSign® device should remain in its original sealed
pouch until ready for use. Do not use the test if the pouch isdamaged or the seal is broken.
Negative: The appearance of a reddish-purple Control line (C)
and a line next to Test position (T) indicates a negative test result;
Do not use the test kit after the expiration date.
i.e., no drug above the cutoff level has been detected. The colorintensities of the Control line and a specific drug line may not be equal. Any faint line in the Result window, visible in 10 minutes, The AccuSign® MET test kit should be stored at 2–30°C (35–
should be interpreted as negative. A negative test result does not 86°F) in the original sealed pouch. The expiration dating was indicate the absence of drug in the sample; it only indicates the established under these storage conditions.
sample does not contain drug above the cutoff level in qualitativeterms. Positive: The appearance of a reddish-purple Control line and no
Approximately 110 µL of urine sample is required for each test.
distinct line next to T indicates the test result is positive for MET Fresh urine specimens do not require any special handling or (i.e., the specimen contains the drug at a concentration above the pretreatment. Specimens should be collected in a clean glass or cutoff level). A positive test result does not provide any indication plastic container. If testing will not be performed immediately, of the level of intoxication or urinary concentration of the drug in specimens should be refrigerated (2–8°C) or frozen. Specimens the sample; it only indicates the sample contains drug above the should be brought to room temperature before testing.
cutoff level in qualitative terms. Specimens containing a large amount of particulate matter may Invalid: A distinct Control line (C) should always appear. The
give inconsistent test results. Such specimens should be clarified test is invalid if no Control line forms at the C position. Such tests
by centrifuging or allowing to settle before testing.
should be repeated with a new AccuSign® MET test device.
The test procedure consists of adding the urine sample to the The test is designed for use with unadulterated urine only.
Sample well of the device and watching for the appearance of There is a possibility that factors such as technical or proce- colored lines in the Test and Control positions.
dural errors, as well as other substances in the urine samplewhich are not listed in Table 5 below, may interfere with the 1. For each test, open one AccuSign® MET Adulterants, such as bleach and/or alum, in urine specimens and label the device with the patient ID.
may produce erroneous results regardless of the method ofanalysis. If adulteration is suspected, the test should be re- 2. Holding the dropper vertically, dispense 3 full drops (110 µL) of the urine sample into the The test result read after 10 minutes may not be consistent with 3. Read the result after 3 minutes, but within 10 the original reading obtained within the 10 minute reading In a separate study, AccuSign® MET was evaluated against speci-
period. The test must be read within 10 minutes of sample mens confirmed as positive by GC/MS. Of 89 samples confirmed as positive, 88 samples were positive when tested with AccuSign®
MET (98.9% agreement). (Table 2.)
Table 2. Accuracy: Comparison of AccuSign® MET with
Internal Control: Each AccuSign® MET test device has a built-
GC/MS Assay
in control. The Control line is an internal positive procedural AccuSign®
control. A distinct reddish-purple Control line should appear in theControl position, if the test procedure is performed properly, an adequate sample volume is used, the sample and reagent are wicking on the membrane, and the test reagents at the control lineand the conjugate-color indicator are reactive. In addition, if the test is performed correctly and the device is working properly, thebackground in the Result window will become clear and provide The precision of AccuSign® MET was determined by carrying out
a distinct result. This may be considered an internal negative the test with serially diluted standard drug solutions. About 98% of the samples containing methamphetamine concentrations 25%over the cutoff level consistently showed positive results.
The positive and negative procedural controls contained in each
AccuSign® MET test device satisfy the requirements of testing a
The study also included over 40 samples containing ± 25% of the positive control and a negative control on a daily basis. If the cutoff level as a challenge of cutoff precision. These results were Control line does not appear in the Control position, the test is found to be consistently in agreement with expected test results.
invalid and a new test should be performed. If the problem persists, Distribution of Random Error:
contact PBM for technical assistance.
Twenty blind samples prepared by spiking various concentrations External Control: External controls may also be used to assure
of methamphetamine were separately tested by two operators. The that the reagents are working properly and that the assay procedure test results from the two operators showed complete agreement.
is followed correctly. It is recommended that a control be tested atregular intervals as good laboratory testing practice. For informa- tion on how to obtain controls, contact PBM’s Technical Services.
The reproducibility of the test results of AccuSign® MET was
examined at three different sites using a total of 15 blind controls,consisting of 5 negative samples, 5 moderately positive samples AccuSign® MET is a qualitative assay. The amount of metham-
(containing the drug at a concentration 1.5-2 times the cutoff level), phetamine and/or their metabolites present in urine cannot be and 5 strongly positive samples (containing the drug at a concen- estimated by the assay. The assay results distinguish positive from tration 4-5 times the cutoff level). The results obtained at these negative samples. Positive results indicate the samples contain three sites with these controls demonstrated 100% agreement with methamphetamine and/or their metabolites above the cutoff con- The following table lists compounds that are detected by the The AccuSign® MET test has been shown to detect an average
AccuSign® MET test. The specificity of the AccuSign® MET test
cutoff of 1000 ng/mL of D-methamphetamine in urine.
was determined by adding the drugs and drug metabolites listed to The accuracy of AccuSign® MET was evaluated in comparison to
drug-negative urine specimens and testing with the AccuSign®
a commercially available immunoassay, Syva® EMIT® II. A total MET test kit. The results are expressed in terms of the concentration
of 320 samples was tested with both procedures. Overall agree- required to produce a positive result. (Table 3.) ment of 91.3% was observed, as shown below. (Table 1.) Table 3. Specificity
Table 1. Accuracy: Comparison of AccuSign® MET with
Concentration
Syva® EMIT® II
Compound
The following compounds show no cross-reactivity when tested with AccuSign® MET at a concentration of 100 µg/mL. (Table 4.)
Table 4. Non Cross-Reacting Compounds
Hawks RL, Chiang CN, eds. Urine Testing for Drugs of Abuse.
Rockville, MD: National Institute for Drug Abuse (NIDA), Research Baselt RC. Disposition of Toxic Drugs and Chemicals in Man. 2nd Ed., Davis, CA: Biomedical Publ.;1982; p.488.
In Vitro Diagnostic Medical Device “Use By” date in year-month-day format AccuSign® is a Registered Trademark of Princeton BioMeditech Corporation.
MT Promedt Consulting GmbH
Princeton BioMeditech Corporation

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