LAUSR

Synthetic cannabinoids (SCs) have become established drugs of abuse. They play an increasing role in drug therapy, where abstinence control testing is required. Differentiation between recent drug uptake and uptake in the distant past is important for drug therapy. This study aimed at evaluating the detection window of a metabolite commonly used as a consumption marker for AB-FUBINACA and AMB-FUBINACA (synonym: FUB-AMB) in urine analysis. The acidic hydrolysis metabolite was quantified in urine samples of a drug user applying a validated analytical method. The concentration profile of the metabolite was correlated with usage data of the subject. Pharmacokinetic properties of AB-FUBINACA were collected by analysis of serum and urine samples from a controlled administration study (single oral ingestion of AB-FUBINACA). Thirteen urine samples were taken without advance notice over 2 years. The metabolite was detected in the first urine sample at 0.77 ng per mg creatinine and subsequently in concentrations ranging from 0.06 to 0.29 ng per mg creatinine. Usage data showed credible abstinence from SCs during this period. The pharmacokinetic properties observed within the controlled self-administration study supported the hypothesis of distribution in deeper compartments and long-lasting elimination (serum concentration-time curve showing biphasic kinetics). An elimination phase of over one year after the last drug uptake seems plausible in cases of extensive consumption. To avoid misinterpretation of positive findings, we recommend testing patients with known SC use at the beginning of abstinence program and to re-test continuously in short time intervals. These data enable correct interpretation of analytical findings.