Excretion profile of 4-methylthioamphetamine in dogs

4-Methylthioamphetamine (4-MTA) is a new drug of abuse, and owing to a number of deaths in the EU over a 2-year period, it has become a major cause for concern. Little is known about the metabolism, half-life or excretion profile of 4-MTA, in man. We used a canine model to study the excretion profile of 4-MTA. Urine samples were screened for 4-MTA with EMIT amphetamine immunoassay, followed by confirmatory analysis using GC-MS. 4-MTA was detectable using EMIT-amphetamine immunoassay down to 1 μgmL^-1 in drug- free urine samples to which 4-MTA was added. 4-MTA was detectable by EMIT up to 23 h after administration. Base extracted urine samples were subjected to flash derivatization using N methylbis(trifluoroacetamide) and the resulting trifluoroacetylated compound yielded a well fragmented mass spectrum under the GC-MS conditions used. Quantification of 4-MTA in the urine samples revealed 15, 11 and 20 μg mL^-1 at 5.5, 13.5 and 23h, respectively. 4-MTA is detectable by immunoassay at 1 μg mL^-1 and can be detected in dogs up to 23 h after administration. EMIT positive screens can be checked using GC- MS incorporating derivatization to confirm the presence of 4-MTA.