Drug stability in forensic toxicology

Abstract

Knowledge of the stability of analytes in solvents and biological matrices is of high importance in the field of forensic toxicology. This is particularly true where quantitative analysis is undertaken; degradation of analytes will result in under-estimation of concentrations, whereas the production of analytes/ metabolites will lead to over-estimation. Although stability is included as part of method validation, this typically focuses on processed sample stability, and the impact of freeze/thaw cycles upon analytes. Although beneficial for method evaluation, this does not assist laboratory analysts with the short-and long-term storage of samples prior to this step and does not consider the impact the biological matrix may have on the degradation or production of the analyte in question. The timeframe for these studies is also relatively short (typically 72 h), which does not cover the time frame between sample receivership and analysis for many forensic cases. This review collects previously published work on long-term stability studies, grouping compounds into their associated drug classes and matrices. Research shows that the majority of compounds are more stable at lower storage temperatures, and that analysis should be completed as quickly as possible. It is advised that analyte stability be considered prior to any interpretation of concentrations in a forensic setting.

Decoding the chemical clues: The role of advancements in forensic toxicology

“…In order to maintain the integrity of evidence, forensic toxicologists are required to adhere to meticulous rules aimed at preventing contamination and preserving the chain of custody. [25] Another obstacle is presented by the stability of medicines and metabolites in biological matrices. Over a period of time, the degradation of these chemicals may occur, resulting in challenges when it comes to their detection and quantification.…”

“…It is important for forensic toxicologists to possess knowledge on the degradation rates of certain medicines and then adapt their analytical methodologies appropriately. [25]…”