On-Site Testing of 3,4-Methylenedioxymethamphetamine (Ecstasy) in Saliva with Drugwipe and Drugread: A Controlled Study in Recreational Users

Saliva is an alternative biologic specimen for drugs-of-abuse 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 read-out 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 …