Structural elucidation of two novel degradants of lurasidone and their formation mechanisms under free radical-mediated oxidative and photolytic conditions via liquid chromatography-photodiode array/ultraviolet-tandem mass spectrometry and one-dimensional/two-dimensional nuclear magnetic resonance spectroscopy

Separation and characterization of related substances of Lurasidone hydrochloride by LC-QTOF-MS techniques

In the present study, a reliable LC-QTOF-MS method was developed and employed for the separation and characterization of process-related substances and forced degradation products of Lurasidone hydrochloride. The chromatographic separation was carried out using an Agilent Poroshell 120 Bonus-RP C18 column (100 mm × 4.6 mm, 2.7 µm) and a mobile phase consisting of a gradient elution of 10 mM ammonium formate solution and methanol. The degradation studies followed the guidelines outlined in ICH Q1A (R2). It was observed that Lurasidone hydrochloride exhibited instability under photolytic, alkaline, and oxidative stress conditions, while remaining relatively stable under acidic and thermal stresses. Through positive ESI-QTOF mass spectrometric analysis, fourteen related compounds in total, including both process-related and stress degradation products, were identified based on the accurate masses of parent and product ions and calculated elemental compositions. Amongst these substances, nine had not been previously reported, and their formation mechanisms were speculated. The process-related substances were further confirmed by NMR spectra determination, and suggestions were proposed to eliminate them. This study highlights the potential for monitoring and controlling related substances during the manufacturing processes, providing valuable insights for process optimization and quality control of Lurasidone hydrochloride.

Microbial degradation products of lurasidone and their significance in postmortem toxicology

Recent research reported that lurasidone degrades in unpreserved ante-mortem human whole blood inoculated with microorganisms known to dominate postmortem blood specimens. In vitro degradation occurred at a similar rate to risperidone, known to degrade in authentic postmortem specimens until below analytical detection limits. To identify the lurasidone degradation products formed, an Agilent 6520 liquid chromatograph quadrupole-time-of-flight mass spectrometer (LC-QTOF-MS) operating in auto-MS/MS mode was used. Numerous degradation products not previously reported in prior in vitro or in vivo pharmacokinetic studies or forced degradation studies were detected. Accurate mass data, mass fragmentation data, acetylation experiments, and a proposed mechanism of degradation analogous to risperidone supports initial identification of the major degradation product as N-debenzisothiazole-lurasidone (calculated m/z [M + H]⁺  = 360.2646). A standard was unavailable to conclusively confirm this identification. Retrospective data analysis of postmortem cases involving lurasidone identified the presence of the major degradation product in four of six cases where lurasidone was also detected. This finding is significant for toxicology laboratories screening for this drug in postmortem casework. The major postmortem lurasidone degradation product has consequently been added to the LC-QTOF-MS drug screen at Forensic Science SA (FSSA) to indicate postmortem lurasidone degradation in authentic postmortem blood specimens and as a marker of lurasidone administration in the event lurasidone is degraded to concentrations below detection limits.