Evaluation of Methamphetamine Immunoassay Rapid Test Kits Used in Thailand

Abstract

Two on-site methamphetamine immunoassay kits were evaluated. PointeStep Drug Screen Meth-amphetamine test was imported from the USA. Bioline Methamphetamine test was manufactured in Thailand. Therefore, it is considerably less expensive than the former one. Bioline is available in slide or card and strip form. The strip seemed to be readily to use, not requiring sample cup. Error occurred when the urine level surpassed the maximum level. Despite the large cost per test differential of these two kits, Pointe Step showed several advantages over the Bioline kit. First, the cutoff of PointeStep was 500 ng/ml while the cutoff of Bioline was 1,000 ng/ml, making PointeStep more sensitive to methamphetamine. The Bioline showed ambiguous results, interpreted as borderline, at methamphetamine concentration 1,000 to 5,000 ng/ml. Thus, its sensitivity is still in doubt. Although both test kits showed cross-reactivity with ethylamphetamine, MDMA, and MDEA, PointeStep showed greater cross-reactivity to these analogs and can be used for amphetamine-type stimulants screening when the use of these analogs is suspected. The results from this study confirmed that immunoassays specific to methamphetamine most likely presented cross-reactivity to analogs that are also secondary amines such as MDMA, MDEA, and ethylamphetamine.