Codeine testing in sweat and saliva with the Drugwipe

With the growing interest in drug testing within different sectors of society, there has become a need for drug assays that can be performed immediately at the site of specimen collection. Recently, Securetec (Ottobrunn, Germany) has introduced the Drugwipe, a non instrument-based, on-site immunodiagnostic assay for the detection of drugs on surfaces. Different tests are available for opiates, cocaine and cannabis. To document the applications of the Drugwipe "opiate" on human biological fluids. 60 mg codeine phosphate were orally administered to 6 subjects. First, sweat testing with the Drugwipe was studied. The wiping section of the kit was used to swab the forehead of the subjects for 10 s, at 1, 4, 9 and 24 h after codeine administration. At the same time, for each period, a sweat patch (Pharmchek, USA) was applied to the outer portion of the upper arm. Codeine was then quantified in the patch by GC/MS and the measured concentrations used as reference. In all subjects except one the Drugwipe tested positive for opiates, however with few false negative results. In the second part of the study, results of the Drugwipe were compared with those obtained by GC/MS for saliva. The tongue of the subjects was carefully wiped over a period 24 h, and at the same time a specimen of saliva collected. Although codeine could be detected using the Drugwipe, numerous false negative results were observed. Codeine tested positive by GC/MS but remained negative using the Drugwipe in several cases. This can be explained by a codeine concentration which was too low to show positive with the Drugwipe, interfering substances may be present in saliva or the sampling procedure is inadequate.