Stability, degradation impurities and decomposition kinetics for paliperidone from osmotic tablets

The antipsychotic paliperidone was investigated with a focus on stability, degradation impurities and kinetics reaction profile. Osmotic tablets 3 mg (OROS^® ) were subjected to extraction in an ultrasonic bath and the resulting acidic solution was stressed by forced conditions. Degraded samples were monitored by HPLC-DAD in different storage times for acidic and alkaline hydrolysis, oxidation, heat and photolysis. Photolysis was shown to be a strong degradation factor, with a drug content of 24.64% remaining after 24 h. Oxidation (H₂ O₂ 18%) caused a slow decomposition, with a drug content of 83.49% remaining after 72 h. Through kinetics graphics, first-order reactions were found for oxidation, heat and photolysis. By UPLC-MS analysis, the degraded matrix could be investigated for identification of impurities with m/z 445.3128, m/z 380.8906, m/z 364.9391, m/z 232.9832 and m/z 217.0076, allowing the identification of derivatives N-oxide and with modifications in the lactam, benzisoxazole and pyrimidine rings. Paliperidone in liquid state, like analytical solutions or formulation, must be carefully handled to avoid drug exposure, specially in storage conditions.