*See text for explanation.
*See text for explanation.
2.2. Testing Saliva With Drugwipe/Drugread: A Controlled Study With Methylenedioxymethamphetamine (5)
In 1999, the Instituto Municipal d'Investigació Médica (IMIM) in Barcelona, Spain, performed a controlled, double-blinded study with methylenedioxymethamphetamine (MDMA; "ecstasy") and eight volunteers. Each subject was orally administered a single dose of 100 mg MDMA or placebo. At time zero (0, predose) and at 1.5, 4, 6, 10, and 24 h after MDMA administration, a sample of saliva (1-2 mL) was collected by spitting into a plastic tube and immediately stored at -20°C. Samples were analyzed for MDMA and metabolites by GC-MS. In this study, 2 ^L of each saliva sample were applied to the wiping fleece of Drugwipe Amphetamines (test kit for amphetamines), and the test was performed according to the instructions for use. Drugwipe results were measured with the DrugRead device and compared with the MDMA concentrations determined by GC-MS.
Figure 6 shows the concentration curve of MDMA in the saliva of one of the volunteers after oral administration of 100 mg of MDMA. The maximum in the concentration curve is reached after approx 2 h. The concentration of MDMA in saliva at this point is more than 3000 ng/mL. The window of detection with GC-MS is at least 24 h. The window of detection with Drugwipe/ DrugRead is approx 10 to 12 h and can be adjusted by changing the cut-off value of the Drugwipe/DrugRead system. All subjects showed a similar concentration curve in saliva, and Drugwipe gave a positive result for all volunteers at 1.5 and 4 h after drug administration. After 6 h, only one out of eight subjects gave a negative result. This subject showed the lowest MDMA concentrations among all the volunteers at that time. At 10 h after MDMA administration, it was still possible to detect consumption in five of the eight subjects. For the three subjects who had negative test results, the concentrations of MDMA in their saliva as determined by GC-MS were below the cut-off levels of the Drugwipe device. At 24 h, no positive results were reported.
The concentration curve of the Drugwipe/DrugRead system correlated well with the concentration curve measured with GC-MS. Provided that the sample volume is thoroughly controlled and the Drugwipe/DrugRead system is calibrated to a specific drug, quantitative measurements can be performed. The apparent slower disappearance rate in the DrugRead signal was probably due more to a saturation effect in the Drugwipe test than to the contribution of MDMA metabolites. In fact, MDMA was reported as the principal analyte that could be detected in saliva, while its principal metabolites were found only in minute amounts. Overall, the Drugwipe/DrugRead system not only detects consumption but also recent use of MDMA.
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