Stability of synthetic cathinones in blood and urine

Although there is an observed decline in the number of new psychoactive substances entering the drug market, this phenomenon is still a significant public health problem. Synthetic cathinones are the second largest group of new substances and currently belong to the most frequently confiscated. Their availability and prevalence cause that they are often abused. Because of this, they should be detected and determined as part of routine toxicological screening in materials collected from both the living and cadavers. Recent reports indicate, however, that some of them are unstable in biological matrices. The aim of the study was the systematic evaluation of changes in concentrations of synthetic cathinones in whole blood and urine samples stored long-term under different temperature conditions.

The study involved 17 compounds that were added to blood and urine to obtain a concentration of 100ng/mL. The material was stored at room temperature (24°C), refrigerated (5°C) and frozen (-26°C) for six months. The extraction was initially performed daily, and then at 1-4week intervals. The analyses were carried out using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The calculated drugs content over time allowed the estimation of the half-life and total degradation time of the tested compounds.

The conducted research indicated that the temperature and matrix have a significant influence on the stability of cathinones, as well as the pH. Significant decreases in the concentrations of some analytes were observed within just several dozen hours of storage at room temperature. The most unstable was 4-chloromethcathinone (4-CMC), for which the half-life in blood was determined to be <1day at room temperature, 4days in the refrigerator and 32days in the freezer. On the other hand, the most stable were 3,4-methylenedioxy derivatives (pentylone, eutylone, butylone and dibutylone). Significant differences in the rate of breakdown of cathinones in blood and urine stored at room temperature were observed. The pH of the sample had a great impact on the stability of cathinones, especially in urine.

Many synthetic cathinones are unstable in biological materials. Changes in concentrations are observed even in recommended manner stored samples. This may lead to a lower calculated concentration than when the material was collected or at the time of death. Total decomposition of the substance is also possible. Obtained results emphasize the importance of proper storage of samples and the possibility of pre-analytical changes in concentrations, in particular during routine material transportation.