Degradation Characteristics of a Novel PAF Receptor Antagonist, SY0916, in Aqueous Solution

SY0916 has been proven to be a potent treatment agent against rheumatoid arthritis in preclinical studies and has been shown to be safe in phase I clinical trials. However, SY0916 is unstable in water, which is frequently used in pharmaceutical development processes. The degradation behaviour and stability of SY0916 in aqueous solutions were investigated at different pH levels, periods of time, and temperatures. Two degradation products (DPs) were successfully separated and characterized by liquid chromatography coupled to high-resolution tandem mass spectrometry (LC-HRMS/MS), liquid chromatography coupled to nuclear magnetic resonance with solid phase extraction (LC-SPE-NMR), and nuclear magnetic resonance (NMR). SY0916 decomposed to its α,β-unsaturated ketone in protonic solvents, and the α,β-unsaturated ketone further transformed into its alcohol form through a conjugate addition reaction in aqueous media. The results of this study indicate that the pH of the buffer solutions should be maintained between 3.0 and 3.6 for maximum SY0916 stability. Factors that affect degradation should be carefully controlled to mitigate or avoid drug decay.