Identification, isolation and characterization of potential degradation product in risperidone tablets

Area of Science:

• Pharmaceutical Chemistry
• Analytical Chemistry

Background:

• Risperidone is an antipsychotic medication.
• Understanding drug degradation products is crucial for pharmaceutical quality control.

Purpose of the Study:

• To detect, isolate, and characterize an unknown impurity in risperidone tablets.
• To elucidate the structure and formation mechanism of the identified impurity.

Main Methods:

• Gradient reverse-phase high-performance liquid chromatography (HPLC) for impurity detection.
• Preparative liquid chromatography for impurity isolation.
• Spectroscopic techniques including NMR (1H, 13C, DEPT), MS, and IR for structural elucidation.

Main Results:

• An unknown impurity was detected and quantified in risperidone tablets under accelerated stability conditions (6 months at 40°C/75% RH).
• The impurity, initially below 0.1%, increased to 0.5%.
• The impurity was isolated and structurally characterized as 3-[2-[4-[6-fluoro-1,3-benzoxazol-2-yl]piperidin-1-yl]ethyl]-2-methyl-6,7,8,9-tetrahydro-4H-pyrido[1,2-a] pyrimidin-4-one.

Conclusions:

• The structure of a significant degradation product in risperidone tablets has been identified.
• The formation and mechanism of this impurity under specific storage conditions have been investigated.