On-Site Testing of 3,4-Methylenedioxymethamphetamine
(Ecstasy) in Saliva with Drugwipe and Drugread:
A Controlled Study in Recreational Users, Simona Pichini,1,2
Mo`nica Navarro,2 Magý´ Farre´,2,3 Jordi Ortun˜o,2 Pere Nolasc
Roset,2 Roberta Pacifici,1 Piergiorgio Zuccaro,1 Jordi Segura,2,4
and Rafael de la Torre2,4* 1 Clinical Biochemistry Department,
Istituto Superiore di Sanita`, 00161 Rome, Italy;
Saliva is an alternative biologic specimen for drugs-ofabuse testing with several advantages over conventional matrices such as blood and urine (1, 2), e.g., weak bases tend to concentrate in saliva because its pH is usually more acidic than the pH of plasma. The most important advantage of saliva is the ease of sample collection. Specimens can be obtained in a matter of minutes under direct observation and without embarrassment to the donor. Special devices have recently been introduced that allow analysis of saliva at the site of specimen collection for on-site screening tests. Commercially available on-site devices include two multitest electronic readers, the Cozart Rapidscan® (Abingdon) and the Avitar OralScreen® (Avitar Inc.), and one single-test visual device, the Drugwipe® (Securetec). Drugwipe is the only on-site test on saliva for which results of clinical studies have been published (3, 4). Briefly, Drugwipe is an immunochromatographic test strip, based on the Frontline urine test strip from Boehringer Mannheim (F. Hoffmann- La Roche) (5 ). A pink color in the test window indicates the presence of the analyte to which the test is specifically addressed, and different devices are needed for detection of each class of drugs of abuse. Although Drugwipe was designed to be read visually, evaluation of color intensity may be highly subjective, and easy readout of the resulting coloration may be hindered by poor light conditions. For this reason, a Drugread® hand photometer has recently been developed. Drugread measures, in a reflectometric mode through a photodiode, the absorbance of the monochromatic light produced by gold antibody conjugates in the read-out area of the Drugwipe. Drugread translates the color intensity in the read-out window into a numeric value (arbitrary units) in the range of 300-2500. To date, no definitive threshold has been established for differentiating samples containing an analyte under investigation from samples not containing the substance....
Several cases of acute intoxication leading to death have been reported, and law enforcement agencies are increasingly interested in roadside on site testing of potentially intoxicated drivers (4 ). We evaluated the suitability of saliva testing of MDMA with the Drugwipe “amphetamines” and Drugread in individuals administered a single oral dose of 100 mg of MDMA....
...On the basis of observations made in the present study, we recommend that direct wiping be avoided, preferring application of an established volume of saliva that could allow delivery of a sufficient quantity to the test pad, which can be easily done “on site” by collecting saliva and applying it to the test pad. In the future, manufacturers of Drugwipe may want to standardize batch-to-batch devices to preselected concentrations for amphetamine-related drugs, taking into account the differences in doses and routes of administration currently in use as well as the time window to be covered by the analytic device in relation to peak effects of the drug. In fact, although a limited number of individuals participated in this study,the present results show that the Drugwipe in combination with the Drugread adequately detected MDMA in saliva in the first 6 h after administration.
On the other hand, the analytic device gives a negative response in a range of salivary concentrations down to 450 g/L (0.9 ng of MDMA in 2 L of saliva applied to the test pad). These concentrations can be found in individuals 6–10 h after the administration of 100 mg of MDMA, corresponding to a mean range of 80–120 g/L in plasma and 3–12 mg/L in urine (10, 11). Conversely, the 0–6 h time window is the period of maximal pharmacologic effects of MDMA. In this time interval, an individual is at highest risk of psychomotor impairment that may have consequences in some demanding tasks, such as driving. Six hours after MDMA ingestion, although the drug is still present in several biologic fluids, most subjective and physiologic effects (i.e., cardiovascular function) return to basal conditions (10 ). Hence, if the objective of on-site saliva testing is not only to detect the consumption of a given drug but also to determine whether an individual is under the effects of the drug, on-site saliva testing with the Drugwipe coupled with the Drugread fits that purpose. Ultimately, appropriate confirmation with a reference chromatographic method for saliva samples should be performed.
